Download Addendum To General Technical Report SE

Addendum to General Technical Report SE-56
Annotated Bibliography of Publications on Watershed Management
And Ecological Studies at Coweeta Hydrologic Laboratory,
For The Period
1994 – November 2003
1. Aber, John D.; Magill, Alison; McNulty, Steven G.; Boone, Richard D.; Nadelhoffer, Knute J.; Downs, Marty; Hallett,
Richard. 1995. Forest biogeochemistry and primary production altered by nitrogen saturation. Water, Air and Soil Pollution. 85: 16651670.
Results from four intensive site-level manipulations and one extensive field survey in northern temperate and boreal forests show a
consistent set of responses to chronic N additions. These include 1) initial and often large increase in net N mineralization followed by
decreases, 2) increases in net nitrification, 3) increases in N concentration in foliage, and 4) decreased Mg: N and Ca: Al ratios, and
declining tree growth and vigor in all evergreen stands. These results are synthesized into a set of proposed summary relationships that
define the temporal pattern of responses of N-limited systems to N additions.
2. Allen, C.J.; Heyes, A. 1998. A preliminary assessment of wet deposition and episodic transport of total and methyl mercury from
low order Blue Ridge watersheds, S.E. U.S.A. Water, Air, and Soil Pollution. 105: 573-592.
Results from a preliminary sampling program designed to investigate total (THg) and methyl Hg (MeHg) deposition, cycling and
transport at the Coweeta Hydrologic Laboratory western North Carolina are presented. Wet deposition samples were collected in June
and July 1994 and throughfall, seep, and streamwaters were intensively collected during and after a rainfall event in June 1994. All water
samples were collected using ultra clean trace sampling protocol. Low elevation Watershed 18 streamwater THg concentrations peaked
with discharge, increasing 6 fold to 9 ng L-1. High elevation Watershed 27 which received less than one half the precipitation Watershed
18 received during the event, exhibited THg concentrations only 1.3 times over base flow conditions. Methyl Hg concentrations
remained near detection limits in both streams. Dissolved MeHg concentrations were higher in shallow seep, throughfall, and
precipitation than streamwaters. Initial estimates of annual THg and MeHg deposition and transport indicate >90% retention of THg and
a >80% retention or demethylation of wet deposition MeHg is occurring in these low order watersheds.
3. Alverson, Andrew J.; Courtney, Gregory W. 2001. Niche overlap of sympatric Blepharicera larvae (Diptera: Blephariceridae)
from the southern Appalachian mountains. Journal of the North American Benthological Society. 20(4): 564-581.
The southern Appalachian Mountains are home to the greatest diversity of Blepharicera (Diptera) in North America, with 13
Blepharicera Macquart species inhabiting the region. Sympatric Blepharicera species seem to occupy a common ecological niche, in
contradiction to the competitive exclusion principle. Instar IV Blepharicera larvae were studied to determine whether dietary differences
facilitate coexistence of sympatric species. Diatom assemblage of Blepharicera diets, total diatom biovolume ingested, and similarity
between diatom assemblage of larval diets and the forage base were examined. Dietary characteristics were compared among
Blepharicera species within and between discrete microhabitats at 3 sites in southern Appalachian. Data showed broad dietary overlap
among species that co-occurred in the same microhabitat and strong microhabitat effects on larval dietary assemblages. In addition,
several species ingested disproportionately greater biovolumes of small andante and prostrate diatom species compared to their
availability on the substratum. Sympatric Blepharicera species may not partition food resources where spatial overlap is most acute.
4. Andre, Henri; Ducarme, Xavier; Anderson, Jo; Crossley, David, Jr.; Koehler, Hartmut; Paoletti, Maurizio; Walter, David;
Lebrun, Philippe. 2000. Rebuttal letter re: Skilled eyes are needed to go studying the richness for the soil. Nature. 409(761):.
Rebuttal Letter reference to: Copley; 2000. J. Nature. 406, 452.
5. Autry, A.R.; Fitzgerald, J.W. 1991. Determination of kinetic parameters for sulfur processing potentials: verification of the
constant specific activity approach. (Short communication). Soil Biology and Biochemistry. 23(10): 1003-1004.
A modification of the "heterotrophic activity method" of Wright and Hobbie (1966) was used to determine kinetic parameters for organic
S formation and sulfate adsorption by forest soil. Kinetic parameters for sulfate adsorption, including saturation potentials and the
concentration of added sulfate yielding saturation, can be determined by visual inspection of the saturation curves. Samples were
collected from the A, B, BC, and C-horizons of an eastern white pine forest (Watershed 1) located at the Coweeta Hydrologic
Laboratory.
6. Autry, A.R.; Fitzgerald, J.W. 1991. Potential for organic sulfur accumulation in a variety of forest soils at saturating sulfate
concentrations. Biology and Fertility of Soils. 10: 281-284.
Increasing the sulfate concentration and concomitant increases in the organic S concentration failed to exert any effect on organic S
mobilization in samples collected from all depths within the mineral soil profile, from 15 sites differing in soil type, vegetation, and
geographic location. Mobilization capacities at saturating concentrations of sulfate for organic S formation generally tended to increase
with increasing depth. The potentials for the accumulation of organic S with various sulfate inputs exhibited saturation kinetics similar
to those observed for organic S formation.
7. Baer, Sara G.; Siler, Edward R.; Eggert, Susan L.; Wallace, J. Bruce. 2001. Colonization and production of macroinvertebrates
on artificial substrata: upstream-downstream responses to a leaf litter exclusion manipulation. Freshwater Biology. 46: 347-365.
Macroinvertebrate colonization dynamics were examined on artificial substrata in a stream with terrestrial litter inputs excluded,
downstream of the litter-exclusion treatment, and in a reference stream. Short-term examination of the rates of organic matter accrual
and invertebrate colonization demonstrated significantly lower accumulation of leaf detritus and invertebrates in the litter-excluded reach
and a short distance downstream of that reach. All major fractions of organic matter and invertebrates declined on artificial substrata
during the 3-year litter exclusion. Further, secondary production on artificial substrata in the litter-excluded reach decreased from 6.2 to
1.5 g AFDM m-2 year-1 from pretreatment to the third year of litter exclusion, respectively. Downstream, fine particulate organic matter
on artificial substrata decreased during litter exclusion, and there was a significant reduction in colonization of collector-filterers. Total
secondary production downstream of the litter exclusion declined >70%, demonstrating that downstream colonization dynamics are
linked to upstream detritus inputs and processing by stream invertebrates.
8. Baker, T.T.; Van Lear, D.H. 1998. Relations between density of rhododendron thickets and diversity of riparian forests. Forest
Ecology and Management. 109: 21-32.
Rosebay rhododendron (Rhododendron maximum L.) is increasing its range and abundance in understories of southern Appalachian
forests, reducing species richness, and altering patterns of succession. This study characterized the density and biomass attributes of R.
maximum thickets and examined their effects on plant species richness, percent cover, and regeneration patterns within a southern
Appalachian riparian ecosystem. R. maximum reached densities exceeding 17,000 stems ha-1 with biomass reaching 34 Mg ha-1. Species
richness and percent cover in the regeneration layer were inversely related to R. maximum thicket density in both spring and fall
samplings. On average, 6 plant species were found on plots with high R. maximum stem density as compared to 26 species found on
plots with lower stem density. The regeneration layer was dominated by R. maximum with only low numbers of tree species present.
Both woody and herbaceous species regenerated poorly under the dense canopy of these thickets. Based on the age of cut stems, R.
maximum became increasingly dominant in the understory of Wine Spring Creek over the last three decades. Its proliferation is altering
the richness of riparian forests and changing historical patterns of community succession.
9. Bardgett, R.D.; Anderson, J.M.; Behan-Pelletier, V.; Brussaard, L.; Coleman, D.C.; Ettema, C.; Moldenke, A.; Schimel,
J.P.; Wall, D.H. 2001. The influence of soil biodiversity on hydrological pathways and the transfer of materials between terrestrial and
aquatic ecosystems. Ecosystems. 4: 421-429.
The boundaries between terrestrial and aquatic ecosystems, known as critical transition zones (CTZ), are dynamic interfaces for fluxes of
water, sediment, solutes, and gases. Moreover, they often support unique or diverse biotas. Soils, especially those of riparian zones, have
not been recognized as CTZ even though they play a critical role in regulating the hydrologic pathways of infiltration and leaching, or
runoff and erosion, which can cumulatively affect biogeochemical processes and human livelihoods at landscape scales. In this review,
we show how the processes that regulate hydrologic fluxes across and through soil CTZ are influenced by the activities of soil biota. Our
message is fourfold. First, there are a variety of ways in which soil biodiversity, in terms of richness and dominance can influence
hydrological pathways in soil and thus the transfer of materials from terrestrial to aquatic ecosystems. Second, the influence of soil
organisms on these hydrological pathways is very much interlinked with other environmental, soil biophysical, and vegetation factors
that operate at different spatial and temporal scales. Third, we propose that the influence of soil biodiversity on hydrological pathways is
most apparent (or identifiable), relative to other factors, in situations that lead to the dominance of certain organisms, such as larger
fauna. Fourth, soils are buffered against environmental change by biophysical properties that have developed over long periods of time.
Therefore, the effects of changes in soil biodiversity on hydrological processes at the ecosystem scale might be delayed and become
most apparent in the long term.
10. Bartman, Chad E.; Parker, Kathleen C.; Laerm, Joshua; McCay, Timothy S. 2001. Short-term response of Jordan’s
salamander to a shelterwood timber harvest in western North Carolina. Physical Geography. 22(2): 154-166.
The effects of shelterwood cutting on the abundance of Jordan’s salamander (Plethodon jordani) in western North Carolina were
examined during 1997 and 1998. Terrestrial salamander assemblages were sampled before, immediately after, and one year after timber
harvest on control and treatment plots to estimate abundance. We also surveyed salamanders immediately after the harvest along
transects radiating out from cut plots to determine whether cutting triggered salamander emigration from disturbed plots. Both before
and after timber harvest, the site was strongly dominated by Jordan’s salamander. No significant effects of initial shelterwood cutting on
Jordan’s salamander abundance were apparent after timber harvest. Abundance of this species decreased from precutting to post-cutting
sampling on both control and treatment plots, which likely reelected the drought that characterized both post-cutting sampling periods,
but not pre-cutting sampling. No emigration of salamanders from the cut plots was detected after timber harvest. These findings suggest
that at a stand scale, shelterwood harvests may pose less of a short-term threat to salamander populations than clearcutting, but more
study is necessary to assess broad-scale tradeoffs between harvest yield and biological impacts associated with alternative timber harvest
methods.
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11. Beckage, Brian; Clark, James S. 2003. Seedling survival and growth of three forest tree species: the role of spatial heterogeneity.
Ecology: 84(7): 1849-1861.
Spatial heterogeneity in microenvironments may provide unique regeneration niches for trees and may promote forest diversity. We
examined how heterogeneity in understory cover, mineral nutrients, and moisture and their interactions with canopy gaps contribute to
the coexistence of three common, co-occurring tree species. We measured survival and height growth of 1080 seedlings of Acer rubrum
(red maple), Liriodendron tulipifera (yellow poplar), and Quercus rubra (red oak) that were planted in one of five understory treatments:
removal of understory vegetation, trenched, trenched plus removal of understory vegetation, fertilization, and a control. Understory
treatments were replicated in 12 paired gap and canopy environments.
Survivorship varied among species, with Q. rubra having the highest probability of surviving beyond the 1135-day experiment
(probability = 0.64), followed by A. rubrum (probability = 0.27) and L. tulipifera (probability = 0.07). Although canopy gaps and
understory treatments had large effects on survivorship, species survival rankings changed little across microenvironments; Q. rubra had
the highest survival in all microenvironments. In contrast to survival, L. tulipifera had a relative growth rate for height that was three
times greater than that of A. rubrum and Q. rubra in high-resource microenvironments. There was broad overlap among species in
relative growth rates in the remaining seven microenvironments, with no clear top-ranked species.
Differences in seedling growth and survival across these 10 microenvironments may contribute to the coexistence of two of the three
species studied, L. tulipifera and Q. rubra, but not A. rubrum. Q. rubra had higher survival than A. rubrum and L. tulipifera in all
microenvironments, but L. tulipifera tended to grow faster than A. rubrum and Q. rubra in high-resource microenvironments. Despite the
generally poor performance of A. rubrum, it was the only surviving species in some quadrats at the end of the experiment, indicating that
stochastic effects, in conjunction with broad niche overlap, may also contribute to species coexistence. The importance of stochastic
effects will probably increase when differential fecundity across these three species is considered because the high fecundity of A.
rubrum offsets survival and growth disadvantages of its seedlings through their greater total abundance.
12. Beckage, Brian; Clark, James S.; Clinton, Barton D.; Haines, Bruce L. 2000. A long-term study of tree seedling recruitment in
southern Appalachian forests: the effects of canopy gaps and shrub understudies. Canadian Journal of Forest Research. 30: 1617-1631.
We examined the importance of intermediate-sized gaps and a dense shrub layer on tree seedling recruitment in a southern Appalachian
deciduous forest. We created 12 canopy gaps under two contrasting understory conditions: 6 gaps were dominated by the dense, shadeproducing shrub, Rhododendron maximum L., while the remaining gaps were relatively open. Density of first-year and > first-year
seedlings was monitored for 5 years in transects extending from adjacent undisturbed forest through the experimental gaps. We
concurrently measured the understory light environment, soil moisture, litter biomass, and seed rain. Neither species diversity nor
richness consistently increased following gap formation. Acer rubrum L. responded consistently to canopy gaps with increased seedling
densities while most other species, including both shade-tolerant and shade-intolerant species, did not. Seedling densities were especially
low and unresponsive to gap formation in areas dominated by R. maximum. Understory light levels were consistently low beneath R.
maximum and did not increase with canopy gap formation. Our results suggest that dense shrub cover can neutralize recruitment
opportunities in canopy gaps, that seed rain often limits recruitment in gaps, and that canopy gaps that are larger or include understory
disturbance are needed to maintain diversity in these forests.
13. Benfield, E.F. 1997. Comparison of litterfall input to streams. In: Webster, J.R.; Meyer, J.L., eds. Stream organic matter budgets.
Journal of the North American Benthological Society. 16: 104-108.
This chapter is part of a multi-site analysis of organic matter dynamics in streams. This chapter compares litterfall inputs to the streams.
Climate (latitude) and vegetation type were more important than steam order in predicting litter inputs across a broad geographic range
of streams, although within a river basin litterfall decreased with increasing stream order.
14. Benfield, E.F. 1998. Leaf breakdown in stream ecosystems. Chapter 27. In: Hauser, F. Richard; Lambert, Gary A., eds. Methods in
stream ecology. San Diego, CA. Academic Press, Inc.: 579-589.
There are two possible sources of primary energy for streams: instream photosynthesis by algae, mosses, and higher aquatic plants and
imported organic matter from streamside vegetation (e.g. leaves and other parts of vegetation). In small, heavily shaded streams, there is
normally insufficient light to support substantial instream photosynthesis so energy pathways are supported largely by imported
(allochthonous) energy. The bulk of imported energy enters such streams as autumnal leaf fall although additional leaf material may
slide or blow into the stream from riparian zones over the rest of the year. Leaves falling into streams may be transported short distances
but usually are caught by structures in the streambed to form leaf packs (Petersen and Cummins 1974, see also Chapter 11). Leaf packs
are then processed in place by components of stream community in a series of well-documented steps.
15. Benfield, E.F.; Webster, J.R.; Hutchens, J.J.; Tank, J.L.; Turner, P.A. 2000. Organic matter dynamics along a stream-order
and elevational gradient in a southern Appalachian stream. Verhandlungen International Vereinigung Limnologie. 27:1341-1345.
Predictions of the River Continuum Concept include changes in physical factors such as geomorphology and temperature along a streamorder gradient (Vannote et al. 1980). Changes in macroinvertebrate diversity (Allan 1975), biomass (Grubaugh et al. 1996), and
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functional feeding group composition (Minshall et al. 1983) have been shown along such gradients. Changes in a variety of ecosystem
processes along stream continua have also been demonstrated (Minshall et al. 1983, Naiman et al. 1987). Huryn & Wallace (1987) and
Grubaugh et al. (1996) found that macroinvertebrate habitat varies both longitudinally and locally and that sampling a single habitat
(patch) may not be sufficient to reflect community composition throughout a stream continuum. Our objective was to investigate
whether selected organic matter processes vary with patch type along a stream-order/elevational gradient.
16. Benfield, E.F.; Webster, J.R.; Tank, J.L.; Hutchens, J.J. 2001. Long-term patterns in leaf breakdown in streams in response to
watershed logging. International Review of Hydrobiology. 86 (4-5): 467-474.
The watershed of Big Hurricane Branch, Coweeta Hydrologic Laboratory, North Carolina, USA, was logged in 1976. We measured
breakdown rates of experimental leaf packs in this second-order stream prior to logging, during logging, soon after logging, and 3
additional times since then. Leaf breakdown was slow just after logging, apparently due to leaf burial by sediments. Thereafter, leaf
breakdown rates have been consistently faster than before logging and faster than in a reference stream. These differences may be related
to 3 factors. First, the post –logging nitrate concentration has been about 3-10 times higher than pre-logging values in Big Hurricane
Branch and 5 times higher than in reference stream. The high nutrient concentration may be stimulating microbial decomposition
processes in leaf packs. Second, dominance of litterfall by “medium” and “fast” processing leaves from the recovering forest coupled
with relatively high sediment loads during storms may hasten breakdown through physical abrasion. Third, the interaction of high
nutrients and high quality leaves may be attractive to leaf-shredding invertebrates whose feeding activities may also hasten the
breakdown rates.
17. Bolstad, Paul V.; Mitchell, Katherine; Vose, James M. 1999. Foliar temperature-respiration response functions for broad-leaved
tree species in the southern Appalachians. Tree Physiology. 19: 871-878.
We measured leaf respiration in 18 eastern deciduous forest tree species to determine if there were differences in temperature-respiration
response functions among species or among canopy positions. Leaf respiration rates were measured in situ and detached branches for
Acerpensylvanicum L., A. rubrum L., Betula spp. (B. alleghaniensis Britt. and B. lenta L.), Carya glabra (Mill.) Sweet, Cornus florida
L., Fraxinus spp. (primarily F. americana L.), Liriodendron tulipifera L., Magnolia fraseri Walt. Nyssa sylvatica Marsh, Oxydendrum
arboreum L., Platanus occidentalis L., Quercu alba L., Q. coccinea Muenchh, Q. prinus L., Q rubra L., Rhododendron maximum L.,
Robinia psuedoacacia L., and Tilia americana L. in the southern Appalachian Mountains, USA. Dark respiration was measured on fully
expanded leaves at 10, 15, 20, 25, and 30 °C with an infrared gas analyzer equipped with a temperature-controlled cuvette. Temperaturerespiration response functions were fit for each leaf. There were significant differences in response functions among species and by
canopy position within species. These differences were observed when respiration was expressed on a mass nitrogen, or area basis.
Cumulative nighttime leaf respiration was calculated and averaged over ten randomly selected nights for each leaf. Differences in mean
cumulative nighttime respiration were statistically significant among canopy positions and species on temperature-respiration response
functions may need to be considered when making estimates of whole-tree or canopy respiration.
18. Bolstad, Paul V.; Swank, Wayne T. 1997. Cumulative impacts of landuse on water quality in a southern Appalachian watershed.
Journal of the American Water Resources Association. 33(3): 519-533.
Water quality variables were sampled over 109 weeks along Coweeta Creek, a fifth-order stream located in the Appalachian mountains
of western North Carolina. The purpose of this study was to observe any changes in water quality, over a range of flow conditions, with
concomitant downstream changes in the mix of land uses. Variables sampled include pH, HCO32-, conductivity, NO3--N, NH4+-N, PO43-P, Cl-, Na+, K+, Ca2+, Mg2+, SO42-, SiO2, turbidity, temperature, dissolved oxygen, total and fecal coliform, and fecal streptococcus.
Landcover/landuse was interpreted from 1:20,000 aerial photographs and entered in a GIS, along with information on total and paved
road length, building location and density, catchment boundaries, hydrography, and slope. Linear regressions were performed to relate
basin and near-stream landscape variables to water quality. Consistent, cumulative, downstream changes in water quality variables were
observed along Coweeta Creek, concomitant with downstream, human-caused changes in landuse. Furthermore, larger downstream
changes in water quality variables were observed during stormflow when compared to base flow, suggesting cumulative impacts due to
landscape alteration under study conditions were much greater during storm events. Although most water quality regulations, legislation,
and sampling are promulgated for baseflow conditions, this work indicates they should also consider the cumulative impacts of physical,
chemical, and biological water quality during stormflow.
19. Bolstad, Paul V.; Swank, Wayne; Vose, James. 1998. Predicting southern Appalachian overstory vegetation with digital terrain
data. Landscape Ecology. 13: 271-283.
Vegetation in mountainous regions responds to small-scale variation in terrain, largely due to effects on both temperature and soil
moisture. However, there are few studies of quantitative, terrain-based methods for predicting vegetation composition. This study
investigated relationships between forest composition, elevation, and a derived index of terrain shape, and evaluates methods for
predicting forest composition. Trees were measured on 406 permanent plots within the boundaries of the Coweeta Hydrologic Lab,
located in the Southern Appalachian Mountains of western North Carolina, USA. All plots were in control watersheds, without human or
major natural disturbance since 1923. Plots were 0.08 ha and arrayed on transects, with approximately 380 meters between parallel
transects. Breast-height diameters were measured on all trees. Elevation and terrain shape were estimated for each plot. Density and
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basal area were summarized by species and by forest type. Plot data were combined with digital elevation data (DEM), and a derived
index of terrain shape at two sampling resolutions: 30 m and 80 m sources. Vegetation maps were produced using each of four different
methods: 1) linear regression with and without log transformations against elevation and terrain variables combined with cartographic
overlay, 2) kriging, 3) co-kriging, and 4) a mosaic diagram. Predicted vegetation was compared to known vegetation at each of 77
independent, withheld data points, and an error matrix was determined for each mapping method. We observed strong relationships
between some species and elevation and/or terrain shape. Cove and xeric oak/pine species basal areas were positively and negatively
related to concave landscape locations, respectively, while species typically found in the mixed deciduous and northern hardwood types
were not. Most northern hardwood species occurred more frequently and at higher basal areas as elevation increased, while most other
species did not respond to elevation. The regression and mosaic diagram mapping approaches had significantly higher mapping
accuracies than kriging and co-kriging. There were significant effects of DEM resolution on map accuracy, with maps based on 30 m
DEM data significantly more accurate than those based on 80 m data. Taken together, these results indicate that both the mapping
method and terrain data resolution significantly affect the resultant vegetation maps, even when using relatively high-resolution data.
Landscape or regional models based on 100 m or lower resolution terrain data may significantly under-represent terrain-related variation
in vegetation composition.
20. Bolstad, Paul V.; Swift, Lloyd; Collins, Fred; Régnière, Jacques. 1998. Measured and predicted air temperatures at basin to
regional scales in the southern Appalachian mountains. Agricultural and Forest Meteorology. 91: 161-176.
Landscape and temporal patterns of temperature were observed for local and regional networks in the southern Appalachian Mountains
of North America. Temperatures decreased with altitude at mean rates of 7°C/km and 3°C/km. Daily lapse rates depended on the method
and stations used in the calculations. Average daily temperature ranges decreased as elevation increased, from 14°C at 700 m to 7°C at
1440 m, and daily temperature ranges were typically higher in spring and fall at any given station. Daily maximum temperature above
the forest canopy averaged 1.4°C higher at a south-facing station relative to a comparable northwest-facing station, and above-canopy
daily minimum temperatures were depressed at a valley-bottom station. Regional regression models provided a more accurate estimate
of station temperature than either kriging or local lapse models when tested using 35 National Climatic Data Center (NCDC) stations in
the southern Appalachians. Data-splitting tests yielded mean absolute errors (MAE) from 1.39 to 2.30°C for predictions of daily
temperatures. Ten-year biases for an independent data set collected at four stations in the Coweeta Basin ranged from -2.87 to 2.91°C for
daily temperatures, with regional regression performing best, on average. However, tests against another independent data set indicate
regional regression and local lapse models were not significantly different, with mean biases averaged from -2.78 to 2.91°C for dailypredicted temperatures.
21. Bolstad, Paul V.; Vose, James M.; McNulty, Steven G. 2001. Forest productivity, leaf area, and terrain in southern Appalachian
deciduous forests. Forest Science. 47(3): 419-427.
Leaf area index (LAI) is an important structural characteristic of forest ecosystems, which has been shown to be strongly related to forest
mass and energy cycles and forest productivity. LAI is more easily measured than forest productivity, and so a strong relationship
between LAI and productivity would be a valuable tool in forest management. While a linear relationship has been observed between
LAI and forest productivity, most of these data have been collected in needle-leaved evergreen stands. The generality and consistency of
the relationship between LAI and productivity has not been as well established for deciduous forests.
Leaf area index (LAI) and aboveground net primary production (ANPP) were measured on 16 forest stands in the southern Appalachian
Mountains. These stands span a range of elevation, slope position, temperature, and moisture regimes. LAI averaged 5.8 m2 m-2 and
ranged from 2.7 to 8.2. ANPP averaged 9.2 Mg ha-1 yr-1 and ranged from 5.2 to 11.8 Mg ha-1 yr-1.
LAI and ANPP decreased significantly from cove to ridge sites, and ANPP decreases significantly from low to high elevation (P < 0.05,
linear regression slope). Elevation-related differences in ANPP do not appear to be due to changes in precipitation, leaf nitrogen content,
or site N mineralization rates.
Linear ANPP-LAI equations fit to the data measured in this study were significant (P < 0.05). These relationships were not significantly
different (P> 0.1) from linear relationships based on data reported in most other studies of ANPP and LAI in eastern deciduous forests of
North America. However, the slope of a linear regression model based on North American eastern deciduous forests was significantly
different (P < 0.05) from one based on data collected in temperate deciduous forests for the rest of the globe. The differences were slight
over the range of observed data, however, and the difference may be due to a narrower range of data for North American deciduous
forests.
22. Bonito, Gregory M.; Coleman, David C.; Haines, Bruce L.; Cabrera, Miguel L. 2003. Can nitrogen budgets explain differences
in soil nitrogen mineralization rates of forest stands along an elevation gradient? Forest Ecology and Management. 176: 563-574.
Nitrogen (N) mineralization rates in forest systems typically decrease with decreasing temperature. Temperature decreases with
increasing elevation. Thus, N mineralization rates are expected to decrease with increasing elevation. However, soil N mineralization
rates at the Coweeta Hydrologic Laboratory, NC, USA are higher at the highest elevation. Causes of higher mineralization rates at the
higher elevation have yet to be explained. Alternative hypotheses to explain patterns of mineralization rates along this elevation gradient
include (1) a mineralization promoter in decomposing promoter in decomposing herbs, leaf litter, or soil of the high elevation, (2) low
pH in the low elevation soils which inhibit mineralization, (3) greater total N pools at the high elevation, (4) low moisture availability in
low elevation soils, (5) differences in soil texture, and (6) differences in biological communities. Previous studies did not support our N
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mineralization promoter hypothesis, nor does soil pH explain mineralization rates. In this study, we constructed N budgets for a high
elevation northern hardwood and a low elevation oak-pine site to determine if differences in N pools and fluxes are sufficient to explain
differences in N mineralization rates. Evaluating N in the upper 0-10 cm of mineral soil, forest floor, overstory biomass, annual canopy
litter fall, understory herb turnover, rainfall, canopy throughfall and in soil solution, we found that the high elevation stand has more
stored N and greater N fluxes than does the low elevation stand. The high elevation stand has many characteristics of a stand in an early
stage of N saturation, while the low elevation stand characterizes an N-limited forest. Causes of greater N storages and fluxes at the high
elevation northern hardwood site are not obvious.
23. Britton, K.O.; Pepper, W.D.; Loftis, D.L.; Chellemi, D.O. 1994. Effect of timber harvest practices on populations of Cornus
florida and severity of dogwood anthracnose in western North Carolina. Plant Disease. 78(4): 398-402.
Stand composition and severity of dogwood anthracnose, caused by Discula destructiva, were measured on 39 plots located at the
Coweeta Hydrologic Laboratory in western North Carolina. The 0.08-ha plots were selected along transects across watersheds previously
clear-cut, partially harvested, or not harvested. Basal diameter, percent leaf area with dogwood anthracnose symptoms, and percent
branch dieback were estimated for Cornus florida. Dogwood anthracnose was most severe on partially harvested watersheds and least
severe on the clear-cut watershed. Density of C. florida was greatest on the clear-cut watershed, and the number of dogwood stems was
inversely correlated (r=-0.31, P=0.05) with disease severity. Dogwood basal area, species importance value, and stand basal area were
not significantly affected by harvest treatment and were not correlated with disease severity. In a second study, anthracnose severity was
rated in 21 plots of yellow poplar near Asheville, North Carolina, that had been thinned to varying densities in the early 1960s. Among
these 0.1-ha plots, thinning intensity did not affect disease severity. Disease severity was inversely related to dogwood size.
24. Bruce, Richard C. 1996. Life-history perspective of adaptive radiation in desmognathine salamanders. Copeia. 4: 783-790.
This study investigates interspecific variation in age at first reproduction, fecundity, and body size in multispecies assemblages of
desmognathine salamanders. The hypotheses tested are that interspecific differences in body size among desmognathines stem
proximately from variation in age at first reproduction and that variation in the latter trait is positively correlated with variation in
fecundity among species. It is shown that a correlation between age at first reproduction and fecundity, combined with a uniform rate of
survival, based on available estimates of these parameters, will yield equivalent values of net reproductive rate (R o) among the species of
a given assemblage. Such equivalence represents a form of life-history symmetry. Data from two assemblages are presented in support
of the argument for symmetry. Such life-history symmetry may reflect uniformity in morphological specialization in desmognathines.
Given the morphological adaptations to burrowing (head-wedging) in the subfamily, the relationship between adult body size and habitat
preference in Desmognathus may reflect adaptation to the size of cover objects and composition of substratum along the aquaticterrestrial habitat gradient. I propose that these variables, in association with predation and competition, represent the selective factors
responsible for body size diversification in Desmognathus.
25. Bruce, Richard C.; Castanet, Jacques; Francillon-Viellot, Helene. 2002. Skeletochronological analysis of variation in age
structure, body size, and life history in three species of desmognathine salamanders. Herpetologica. 58(2): 181.193.
We evaluated age structure in three species of desmognathine salamanders at Coweeta Hydrologic Laboratory, North Carolina, for
comparison with the results of an earlier study of age structure in these species at a nearby locality (Wolf Creek, North Carolina). At
Coweeta, both Desmognathus quadramaculatus and D. monticola attain larger adult body sizes and greater ages than their Wolf Creek
counterparts. The differences appear to stem in part from greater ages at sexual maturation in both species at Coweeta versus Wolf
Creek. This disparity is most pronounced in D. quadramaculatus, where the estimated ages at first reproduction are 7-8 yr. in males and
9-10 yr. in females. The Coweeta populations of D. quadramaculatus and D. monticola may also have higher survivorship and higher
rates of post-maturational growth than those at Wolf Creek. In contrast, in the third and smallest species, D. ocoee, the Coweeta
population did not differ in size and age attributes from that at Wolf Creek. We hypothesize that the more mesic climate of Coweeta
versus Wolf Creek is a safer environment for the two larger, aquatic to semi-aquatic desmognathines, eliciting selection for later
maturation and thus larger body sizes. In contrast, selection on the life history of the smaller and more terrestrial D. ocoee at both
localities may derive mainly from factors other than the climatic differential.
26. Burt, Tim; Swank, Wayne. 2002. Forest or floods? Geography Review. 15(5): 37-41.
This article shows how experiments at the Coweeta Hydrologic Laboratory in North Carolina have deepened our understanding of the
ways in which forested catchments respond to land use change. Human impact on stream discharge as a result of changes in vegetation
cover is an important theme.
27. Burton, A.J.; Pregitzer, K.S.; Ruess, R.W.; Hendrick, R.L.; Allen, M.F. 2002. Root respiration in North American forests:
effects of nitrogen concentration and temperature across biomes. Oecologia. 131: 559-568.
Root respiration rates have been shown to be correlated with temperature and root N concentration in studies of individual forest types or
species, but it is not known how universal these relationships are across forest species adapted to widely different climatic and edaphic
conditions. In order to test for broad, cross-species relationships, we measured fine root respiration, as 02 consumption, over a range of
6
temperatures on excised root samples from ten forested study sites across North America in 1997. Significant differences existed among
study sites in root respiration rates, with patterns among sites in respiration rate at a given temperature corresponding to differences among
sites in fine root N concentrations. Root respiration rates were highly correlated with root N concentrations at all measurement temperatures
(r(2)>0.81, P<0.001, for 6, 18 and 24degreesC). Lower root respiration rates in gymnosperms than in angiosperms were largely explained
by lower fine root N concentrations in gymnosperms, and root N concentrations and respiration rates (at a given temperature) tended to be
lower at warm sites (New Mexico, Florida, and Georgia) than at cool sites with short growing seasons (Michigan and Alaska). Root
respiration rates increased exponentially with temperature at all sites. The Q(10) for root respiration ranged from 2.4 to 3.1, but there were
no significant differences among the forest types. The average Q(10)s for gymnosperms (Q(10)=2.7) and angiosperms (Q(10)=2.6) were
almost identical, as were the average Q(10)s for roots of ectomycorrhizal species (Q(10)=2.7) and arbuscular mycorrhizal species
(Q(10)=2.6). In 1998, fine root respiration at the study sites was measured in the field as CO, production at ambient soil temperature.
Respiration rates under field conditions were dependent on both ambient soil temperature and root N concentration. Relationships between
respiration (adjusted for temperature) and root N concentration for the field measurements were similar to those observed in the 1997
laboratory experiments. For root respiration in tree species, it appears that basic relationships with temperature and nitrogen exist across
species and biomes.
28. Chen, T.H.; Hornberger, G.M.; Jakeman, A.J.; Swank, W.T. 1995. The performance of different loss models in the simulation
of streamflow. Environmetrics. 6: 479-484.
The performance of a new approach to separate hydrographs and parameterize their response behavior for describing the rainfall-runoff
process was examined using data from Coweeta Watershed 36 (USA) and Queanbeyan River (Australia). The model tested consists of
two modules; the non-linear module represents the rainfall-loss process and the linear module converts excess rainfall to streamflow.
Evaluations of three different formulations of the rainfall-loss model showed good estimation and simulation performance at Coweeta
for all three cases but Case 2 was judged as superior. For Queanbeyan, Case 2 was again the best for model estimation and Case 1
provided reasonably good performance for model simulation.
29. Chung, K.; Wallace, J.B.; Grubaugh, J.W. 1993. The impact of insecticide treatment on abundance, biomass, and production of
litterbag fauna in a headwater stream: a study of pretreatment, treatment, and recovery. Limnologica. 28(2): 93-106.
The insecticide methoxychlor was applied seasonally for three years to a small headwater stream at Coweeta Hydrologic Laboratory.
Invertebrate fauna colonizing litterbags and litter processing rates in the treatment and a reference stream were examined prior to and
during treatment and for two recovery years. During treatment, leaf-processing rates were less than 50% of rates in pretreatment years.
Invertebrate fauna was dominated by large numbers of small collector-gatherers (primarily non-insects) and predators, whereas insect
shredders were virtually eliminated. During the first recovery year, populations of non-insect taxa remained high and many insect taxa,
especially those with long life cycles, remained absent or rare. Reappearance of the insect community, especially insect shredders, during
the second recovery year was accompanied by restoration of leaf processing rates. The recovery process of macroinvertebrate
communities in this stream appeared to result from the proximity of numerous headwater streams within the Coweeta basin, which
provide stable source populations.
30. Clark, J.S.; Beckage, B.; Camill, P.; Cleveland, B.; HilleRisLambers, J.; Lichter, J.; McLachlan, J.; Mohan, J.; Wyckoff.
1999. Interpreting recruitment limitation in forests. American Journal of Botany. 86(1): 1-16.
Studies of tree recruitment are many, but they provide few general insights into the role of recruitment imitation for population
dynamics. That role depends on the vital rates (transitions) from seed production to sapling stages and on overall population growth. To
determine the state of our understanding of recruitment limitation we examined how well we can estimate parameters corresponding to
these vital rates. Our two-part analysis consists of (1) a survey of published literature to determine the spatial and temporal scale of
sampling that is basis for parameter estimates, and (2) an analysis of extensive data sets to evaluate sampling intensity found in the
literature. We find that published studies focus on fine spatial scales, emphasizing large numbers of small samples within a single stand,
and tend not to sample multiple stands or variability across landscapes. Where multiple stands are sampled, sampling is often
inconsistent. Sampling of seed rain, seed banks, and seedlings typically span <1 yr and rarely last 5 yr. Most studies of seeding
establishment and growth consider effects of a single variable and a single life history stage. By examining how parameter estimates are
affected by the spatial and temporal extent of sampling, we find that few published studies are sufficiently extensive to capture the
variability in recruitment stages. Early recruitment stages are especially variable and require samples across multiple years and multiple
stands. Ironically, the longest duration data sets are used to estimate mortality rates, which are less variable (in time) than are early life
history stages. Because variables that affect recruitment rates interact, studies of these interactions are needed to assess their full impacts.
We conclude that greater attention to spatially extensive and longer duration sampling for early life history stages is needed to assess the
role of recruitment limitation in forests.
31. Clark, James S. 1998. Why trees migrate so fast: confronting theory with dispersal biology and the paleorecord. The American
Naturalist. 152(2): 204-224.
Reid’s paradox describes the fact that classical models cannot account for the rapid (10²-10³ m yrˉ¹) spread of trees at the end of the
Pleistocene. I use field estimates of seed dispersal with an integrodifference equation and simulation models of population growth to
show that dispersal data are compatible with rapid spread. Dispersal estimates lay to rest the possibility that rapid spread occurred by
7
diffusion. The integrodifference model predicts that, if the seed shadow has a long “fat” tail, then rapid spread is possible, despite short
average dispersal distances. It further predicts that velocity is more sensitive to life history than is classical diffusion. Application of such
models is frustrated because the tail of the seed shadow cannot be fitted to data. However, the data can be used to test a “long-distance”
hypothesis against alternative (“local”) models of dispersal using Akaike’s Information Criterion and likelihood ratio tests. Tests show
that data are consistent with >10% of seed dispersed as a long (10² m) fat-tailed kernel. Models based on such kernels predict spread as
rapid as that inferred from the pollen record. If fat-tailed dispersal explains these rapid rates, then it is surprising not to see large
differences in velocities among taxa with contrasting life histories. The inference of rapid spread, together with lack of obvious lifehistory effects, suggests velocities may have not reached their potentials, being stalled by rates of climate change, geography, or both.
32. Clark, James S.; Carpenter, Steven R.; Barber, Mary; Collins, Scott; Dobson, Andy; Foley, Jonathan A.; Lodge, David M.;
Pascual, Mercedes; Pielke, Roger Jr.; Pizer, William; Pringle, Cathy; Reid, Walter V.; Rose, Kenneth A.; Sala, Osvaldo;
Schlesinger, William H.; Wall, Diana H.; Wear, David. 2001. Ecological forecasts: an emerging imperative. Science. 293: 657-660.
Planning and decision-making can be improved by access to reliable forecasts of ecosystem state, ecosystem services, and natural
capital. Availability of new data sets, together with progress in computation and statistics, will increase our ability to forecast ecosystem
change. An agenda that would lead toward a capacity to produce, evaluate, and communicate forecasts of critical ecosystem services
requires a process that engages scientists and decision-makers. Interdisciplinary linkages are necessary because of the climate and
societal controls on ecosystems, the feedbacks involving social change, and the decision-making relevance of forecasts.
33. Clark, James S.; Fastie, Chris; Hurtt, George; Jackson, Stephen T.; Johnson, Carter; King, George A.; Lewis, Mark;
Lynch, Jason; Pacala, Stephen; Prentice, Colin; Schupp, Eugene W.; Webb, Thompson, III; Wyckoff, Peter. 1998. Reid's
paradox of rapid plant migration: dispersal theory and interpretation of paleoecological records. BioScience. 48(1): 13-24.
Paleorecords suggest trees migrated in response to past climate changes much faster than predicted by simple diffusion. Here we
examine how new theory, based on assumptions of rare, long-distance dispersal, could account for rapid spread. Windstorms and
transport by birds and large vertebrates are potential causes of distant dispersal. Results suggest that population spread in response to
global warming will be determined by the "tail" of the dispersal curve. Populations lacking these mechanisms of long-distance dispersal
will be especially threatened by climate change.
34. Clark, James S.; Ji, Yuan. 1995. Fecundity and dispersal in plant populations: implications for structure and diversity. The
American Naturalist. 146(1): 72-111.
Demographic models of tree populations assume that seed availability does not depend on the populations themselves. We develop
models to assess the consequences of fecundity and dispersal for population’s structure and diversity. Results show that population
structure and reproductive success are importantly affected by seed production and dispersal for realistic parameterization of time scales
describing thinning, disturbance, maturation, and longevity. Maturation age affects mean and variance in seed rain. Populations with
well-dispersed seed have a structure that is most sensitive to maturation age when disturbance is frequent. With restricted dispersal,
delayed maturation means increased variability in seed rain, maximized when half of all patches support reproductive individuals.
Density-dependent thinning compensates for the initial variability conferred by limited dispersal but not enough to permit the neglect of
fecundity and dispersal at the disturbance frequencies and thinning rates typical in many forests. Longevity matters most when it is short
and disturbance rare. To assess the effects of dispersal on reproductive success, we partition the contributions of seed-rain mean and
variance. Fecundity and population structure affect both the mean and the variance in seed rain, albeit in different ways. Dispersal affects
only the variance. The partitioned contribution of mean and variance are used to consider two cases: how dispersal consequences for
reproductive success depend on life-history schedules and disturbance regime, and boundary growth rates of a globally dispersed
population invading a resident population with restricted dispersal. In both cases, restricted dispersal has important consequences on the
scales observed in many real forests. Most models of forest tree dynamics assume a globally dispersed seed pool that is disconnected
from the populations that should produce that seed. This assumption leads to two opposing (offsetting?) consequences for species
diversity: artificially high diversity due to continuous seed supply and artificially low diversity due to lack of sites where good
competitors with restricted dispersal should be absent.
35. Clark, James S.; Lavine, Michael. 2001. Bayesian statistics estimating plant demographic parameters. In: Scheiner SM, Gurevitch
J, eds. Design and Analysis of Ecological Experiments. Oxford, UK:Oxford University Press. p 327–346. Chapter 17.
Bayesian analysis differs from other topics in this book, so we approach it in a different way. Our gentle introduction is intended for the
ecologist who might find either Bayesian or classical approaches useful, depending on the application at hand. So our chapter includes
some comparisons, but they are not the insidious examples that rely on strange or unrealistic distributions to generate discord. Although
most of this book is designed for the practitioner, providing the bridge from concept to software, Bayesian analysis still requires
programming. Thus, although we cannot direct the reader to a broad range of software options, we adopt the general philosophy of this
volume by providing a simple and practical introduction to a topic that is generally treated at a more advanced level in graduate statistic
courses and beyond.
8
36. Clark, James S.; Lewis, Mark; Horvath, Lajos. 2001. Invasion by extremes: population spread with variation in dispersal and
reproduction. The American Naturalist. 157(5): 537-554.
For populations having dispersal described by fat-tailed kernels (kernels with tails that are not exponentially bounded), asymptotic
population spread rates cannot be estimated by traditional models because these models predict continually accelerating (asymptotically
infinite) invasion. The impossible predictions come from the fact that the fat-tailed kernels fitted to dispersal data have a quality
(nondiscrete individuals and, thus, no moment-generating function) that never applies to data. Real organisms produce finite (and
random) numbers of offspring; thus, an empirical moment-generating function can always be determined. Using an alternative method to
estimate spread rates in terms of extreme dispersal events, we show that finite estimates can be derived for fat-tailed kernels, and we
demonstrate how variable reproduction modifies these rates. Whereas the traditional models define spread rate as the speed of an
advancing front describing the expected density of individuals, our alternative definition for spread rate is the expected velocity for the
location of the furthest-forward individual in the population. The asymptotic wave speed for a constant net reproductive rate R-0 is
approximated as (1/T)(pi uR(0)/2)1/2 m yr(-1), where T is generation time, and u is a distance parameter (m(2)) of Clark et al. 's 2Dt
model having shape parameter. From fitted dispersal kernels with fat tails p = 1 and infinite variance, we derive finite rates of spread and
a simple method for numerical estimation. Fitted kernels, with infinite variance, yield distributions of rates of spread that are
asymptotically normal and, thus, have finite moments. Variable reproduction can profoundly affect rates of spread. By incorporating the
variance in reproduction that results from variable life span, we estimate much lower rates than predicted by the standard approach,
which assumes a constant net reproductive rate. Using basic life-history data for trees, we show these estimated rates to be lower than
expected from previous analytical models and as interpreted from paleorecords of forest spread at the end of the Pleistocene. Our results
suggest reexamination of past rates of spread and the potential for future response to climate change.
37. Clark, James S.; Macklin, Eric; Wood, Leslie. 1998. Stages and spatial scales of recruitment limitation in southern Appalachian
forests. Ecological Monographs. 68(2): 213-235.
Recruitment limitation of tree population dynamics is poorly understood, because fecundity and dispersal are difficult to characterize in
closed stands. We present an approach that estimates seed production and dispersal under closed canopies and four limitations on
recruitment: tree density and location, fecundity, seed dispersal, and establishment. Consistent estimates are obtained for 14 canopy
species using 5 yr. of census data from 100 seed traps and several thousand mapped trees and seedlings from five southern Appalachian
forest stands that span gradients in elevation and moisture. Fecundity ranged over four orders of magnitude, from 10° cm 2 basal area/yr
to > 103cm2/yr. Mean dispersal distance ranged from <5 m to >20 m and was positively correlated with fecundity. Species also differ in
the degree of seed clumping at find (1m2) spatial scales. Dispersal patterns can be classed in two groups based on dispersal vector: winddispersed taxa with high fecundities, long-distance dispersal, and low clumping vs. animal-dispersal taxa with low fecundities, shortdistance dispersal, and a high degree of clumping. "Colonization" limitations caused by sizes and locations of parent trees, fecundity, and
dispersal were quantified as the fraction of sites receiving seed relative to that expected under null models that assume dispersal is
nonlocal and not clumped. Difference among species in colonization levels ranged from those capable of saturating the forest floor with
seed in most stands to ones that leave much of the forest floor without seed, despite presence of adults. Seedling establishment is one of
the strongest filters on recruitment in our study area. Taken together, our results indicate (1) that fecundity and dispersal can be
resolved, even under a closed canopy, and (2) that recruitment of many species is limited by the density and location of source, dispersal
patterns, or both.
38. Clark, James S.; Mohan, Jacqueline; Dietze, Michael; Ibanez, Inez. 2003. Coexistence: how to identify trophic trade-offs.
Ecology. 84(1): 17-31.
Analyses of growth response to resource availability are the basis for interpreting whether trophic trade-offs contributes to diversity. If
different species respond most to resources that are limiting at different times, then those differences may trade off with other trophic or
life history traits that, together, help to maintain diversity. The statistical models used to infer trophic differences do not accommodate
uncertainty in resources and variability in how individuals use resources. We provide hierarchical models for resource-growth responses
that accommodate stochasticity in parameters and in data, despite the fact causes are typically unknown. A complex joint posterior
distribution taken over >102 parameters is readily integrated to provide a comprehensive accounting of uncertainty in the growth
response, together with a small number of hyperparameters that summarize the population response. An application involving seedling
growth response to light availability shows that large trophic differences among species suggested by traditional models can be an
artifact of the assumption that all individuals respond identically. The hierarchical analysis indicates broad trophic overlap, with the
implication that slow dynamics play a more important role in preserving diversity than is widely believed.
39. Clark, James S.; Silman, Miles; Kern, Ruth; Macklin, Eric; HilleRisLambers, Janneke. 1999. Seed dispersal near and far:
patterns across temperate and tropical forests. Ecology. 80(5): 1475-1494.
Dispersal affects community dynamics and vegetation response to global change. Understanding these effects requires descriptions of
dispersal at local and regional scales and statistical models that permit estimation. Classical models of dispersal describe local or longdistance dispersal, but not both. The lack of statistical methods means that models have rarely been fitted to seed dispersal in closed
forests. We present a mixture model of dispersal that assumes a range of dispersal patterns, both local and long distance. The bivariate
Student’s t or “2Dt” follows from an assumption that the distance parameter in a Gaussian model varies randomly, thus having a density
9
of its own. We use an inverse approach to “compete” our mixture model against classical alternatives; using seed rain databases from
temperate broadleaf, temperate mixed-conifer, and tropical floodplain forests. For most species, the 2Dt model fits dispersal data better
than do classical models. The superior fit results from the potential for a convex shape near the source tree and a “fat tail.” Our
parameter estimates have implications for community dynamics at local scales, for vegetation responses to global change at regional
scales, and for differences in seed dispersal among biomes. The 2Dt model predicts that less seed travels beyond the immediate crown
influence (<5m) than is predicted under a Gaussian model, but that more seed travels longer distances (>30 m). Although Gaussian and
exponential models predict slow population spread in the face of environmental change, our dispersal estimates suggest rapid spread.
The preponderance of animal-dispersed and rare seed types in tropical forests results in noisier patterns of dispersal than occur in
temperate hardwood and conifer stands.
40. Clark, Jim; Horvath, Lajos; Lewis, Mark. 2001. On the estimation of spread rate for a biological population. Statistics &
Probability Letters. 51: 225-234.
We propose a nonparametric estimator for the rate of spread of an introduced population. We prove that the limit distribution of the
estimator is normal or stable, depending on the behavior of the moment generating function. We show that resampling methods can also
be used to approximate the distribution of the estimators.
41. Clinton, Barton D. 1995. Temporal variation in photo synthetically active radiation (PAR) in mesic southern Appalachian
hardwood forests with and without Rhododendron understories. In: Gottschalk, Kurt W.; Fosbroke, Sandra L.C., eds. Proceedings, 10th
Central Hardwood Forest Conference; 1995 March 5-8; Morgantown, WV. Gen. Tech. Rep. NE-197. Randor, PA: U.S. Department of
Agriculture, Forest Service, Northeastern Forest Experiment Station: 534-540.
Understanding spatial and temporal variation in the understory light regime of southern Appalachian forests is central to understanding
regeneration patterns of overstory species. One of the important contributors to this variability is the distribution of evergreen shrub
species, primarily Rhododendron maximum L. We measured photo synthetically active radiation (PAR) in the understory of closed forest
canopies in areas with and without R. maximum. Measurements were taken from March through November 1993 with a frequency of
approximately 3 weeks. In 1994, measurements resumed from March through May. PAR under sub-canopies of R. maximum averaged
77% (e.g., 14 vs. 65 mmol m-2s-1) lower than in areas without R. maximum during the growing season, and 70% (e.g., 179 vs. 641 mmol
m-2s-1) lower in the dormant season. Variation in PAR during the growing season ranged from 73% to 86% lower in R. maximum versus
non-R. maximum understories. During the growing season, light levels beneath Rhododendron were observed to be <2% of full sun.
Low-light environments associated with R. maximum understories are extremely limiting with respect to regeneration of important
hardwood species.
42. [Clinton, Barton D. et. al.]; Long-Term Intersite Decomposition Experiment Team (LIDET); 1995. Meeting the challenge of
long-term, broad-scale ecological experiments. Publication No. 19. Seattle, WA: LTER Network Office: 23 p.
Answering the challenges of global change research requires an understanding of ecosystem behavior over greater temporal and spatial
scales than have been examined in the past. Several solutions to this problem are possible. Synthesis of past results from individual finescale studies is critical, but uneven geographic distributions, study durations, and methodological incompatibilities all limit the scientific
value of the outcome. An alternative is designing group or team experiments, such as LIDET that can be carried out simultaneously at
many sites. In addition to standardizing methods and predetermining spatial and temporal limits, this approach benefits the individual
sites involved by placing the results from individual sites in a larger context, allowing general access to novel analytical methods, and
creating a greater sense of participation in research on global change. Understanding ecological systems on the global scale will require
an increase in preplanned, long-term, multisite studies. We describe an example of this type of research-a 10-year, 28-site experiment to
test the effect of substrate quality and macroclimate on long-term decomposition and nutrient dynamics.
43. Clinton, Barton, D. 2002. Rhododendron maximum L. Ericaceae. In: Francis, John K. ed. Wildland shrubs of the United States
and its territories: Thamnic descriptions. Gen. Tech. Rep. IITF-WB-1. Rio Piedras, Puerto Rico: U.S. Department of Agriculture, Forest
Service, International Institute of Tropical Forestry and Shrub Sciences Laboratory. www.fs.fed.us/global/iitf/wildland_shrubs.htm.
[n.p.]
Estimating the number of shrub species in the U.S. and its territories is challenging because the life-form is subject to the perception of
authors and compilers and not indicated or consistently identified in many of the checklists and floras. However, it is possible to count
the shrub species indicated in the floras of several of the states or regions. This contribution to a collection thamnic monographs is a
general description of the shrub species Rhododendron maximum L. The author describes the range, ecology, reproduction, growth and
management, benefits, and detrimental effects of the species.
44. Clinton, Barton, D. 2003. Light, temperature, and soil moisture responses to elevation, evergreen understory, and small canopy
gaps in the southern Appalachians. Forest Ecology and Management. 186(1-3): 243-255.
Small canopy openings often alter understory microclimate, leading to changes in forest structure and composition. It is generally
accepted that physical changes in the understory (i.e., microclimatic) due to canopy removal drive changes in basic forest processes,
10
particularly seedling recruitment which is intrinsically linked to soil moisture availability, light and, to a lesser extent, temperature. We
examined the impact of small canopy gaps of the type (snags) and size (~300 m2) most frequently observed in the southern Appalachians
on the understory microclimate. We created artificial canopy gaps at two elevations (a.m.s.l.) by girdling trees in areas with and without
a Rhododendron maximum L. (rosebay rhododendron) understory. Soil and air temperature (°C), photosynthetically active radiation
(PAR; µmol m-2 s-1), and volumetric soil water content (%WC) in the upper 15 cm of soil were measured along transects generally
running north to south through each gap. Overall, PAR was substantially less in rhododendron gaps than in non-rhododendron gaps. We
found a slight increase in PAR in non-rhododendron gaps during spring and summer compared to controls. Very little seasonal variation
in PAR was observed in rhododendron gaps compared with non-rhododendron gaps. In general, %WC in rhododendron gaps was lower
than in non-rhododendron gaps and less variable. We also found a gap response in incident PAR during the spring and summer seasons.
There was no significant effect of gap creation on %WC, nor were there site (elevation) differences or effects due to the presence of
rhododendron. Further, there was no significant gap effect on mean, maximum, or minimum soil and air temperature; however, there
were significant effects from the presence of rhododendron and between sites for PAR and soil and air temperature during certain
seasons of the year. Although there is some certainty about measurable responses in key microclimatic variables in rhododendron and
non-rhododendron gaps found in this study, we could not be certain if responses represent a significant enough departure from values in
undisturbed conditions to elicit a tree recruitment response. Our results indicate that for openings of the size examined here, topography
and evergreen understory are the primary determinants of spatial and temporal heterogeneity in understory microclimate. Published by
Elsevier B.V.
45. Clinton, Barton, D.; Baker, Corey R. 2000. Catastrophic wind throw in the southern Appalachians: characteristics of pits and
mounds and initial vegetation responses. Forest Ecology and Management. 126: 51-60.
We characterized pit and mound (PM) topography resulting from catastrophic wind in the Coweeta Basin, and located 48 PMs across a
variety of forest types. Our measurements included pit length, width, and depth: and mound height, thickness, and width. Species of
fallen trees were identified, and DBH (diameter at breast height 1.37 m) was measured for biomass determination. We identified five
distinct microsites at each PM: mound face, mound top, pit bottom, pit-wall, and intact forest floor. On each microsite, we measured
photosynthetically active radiation (PAR), soil temperature, and soil moisture, and took soil samples from four microsites (intact forest
floor, pit wall, pit bottom, mound top) to determine carbon and nitrogen concentrations. Treefall direction was marginally non-random.
Three PM dimensions were significantly related to fallen tree biomass; mound width; mound height; and pit width. Other relationships
failed because (1) rooting depth of the fallen tree was not necessarily proportional to tree size; and (2) trees that fell striking other trees
often slid back into the pit, altering its dimensions. PAR was highest at mound top (250 µmol mˉ² s ˉ¹) and lowest in pit bottom (70 µmol
mˉ²s ˉ¹). Mean soil temperature varied ≈3°C across mircosites, and soil moisture ranged from 24% on the mound top and mound face to
34% in the pit bottom. Nitrogen and carbon concentrations were significantly higher on the forest floor ([N] =0.23%; [C] = 4.73%) than
on the other three mircosites ([N] = 0.08-0.10%; [C] = 1.4-2.2%). Overtime, soil nutrition and microsite instability, due to erosion and
settling, may be the most influential factors determining rates of vegetative establishment in PMs. We characterized initial vegetative
recovery in 27 blow down sites. Trees were placed in one of two damage classes; direct wind damage (direct); and damage due to the fall
of another tree (indirect). Basal and/or bole sprouting and live or dead crowns were noted. Blow down areas ranged from 181 to 4043 m²
and averaged 1175 m². Mean diameter of indirectly damaged trees was 50% of the mean for trees directly damaged, but both had similar
minimum diameters. Overall, the biomass of indirectly damaged trees accounted for <10% of total biomass but 33% of the total number
of stems. Of the indirectly damaged trees, 38% were topped, 82% exhibited basal or bole sprouting, and 21% had live crowns. By
contrast, of the directly damaged trees, only 5% were topped, <50% were sprouting, and only 11% had live crowns.
46. Clinton, Barton D.; Boring, Lindsay R.; Swank, Wayne T. 1994. Regeneration patterns in canopy gaps of mixed-oak forests of
the southern Appalachians: Influences of topographic position and evergreen understory. American Midland Naturalist. 132: 308-319.
Canopy gaps in southern Appalachian forests were assessed for the effects of topographic, gap, and stand variables on density of woody
seedlings. Density was significantly correlated with percent slope and gap age (1-5 yr), varied substantially among topographic positions,
and increased with gap size. Species richness decreased over time and increased with gap size. Regeneration was dominated by Acer
rubrum L. Other species included Quercus coccinea Muench, Q. rubra L., Q. velutina Lamarck, Liriodendron tulipifera L., and Cornus
florida L. Effects of the evergreen understory (Rhododendron maximum L. and Kalmia latifolia L.) were examined. Gaps containing
over 50% cover of R. maximum had significantly lower densities than all other gaps, including gaps with >50% K. latifolia cover. Height
distributions of regenerating species were skewed away from small (<15 cm) height classes. Species establishment was a function of gap
area, gap age, topographic position, and cover of R. maximum. In addition, species of varying degrees of tolerance of understory
conditions are capable of establishment in small to medium size canopy openings in the absence of evergreen shrub understory.
47. Clinton, Barton D.; Elliott, Katherine J.; Swank, Wayne T. 1997. Response of planted eastern white pine (Pinus strobus L.) to
mechanical release, competition, and drought in the southern Appalachians. Southern Journal of Applied Forestry. 21(1): 19-23.
Conversion of low-quality, natural mixed pine/hardwood ecosystems, containing a mountain laurel dominated understory, to more
productive eastern white pine/mixed hardwood systems is a common prescription on relatively xeric southern Appalachian forest sites.
We examined the effects of mechanical release, interspecific competition, and annual precipitation on growth of planted white pine in
four 14-yr-old stands in the southern Appalachians. Two stands were mechanically released at age 6. No significant differences in
biomass, basal area, or diameter were found between treatments for all species combined. Radial increment was significantly less during
11
a drought year for both treatments. Height increment was less sensitive to severe moisture limitation than radial increment. Height and
radial increment were compared to distance-dependent and distance-independent measures of competition for the nonreleased stands.
Indices based on height and height/distance explained the greatest amount of variation in both radial and height increment. The influence
of post-release severe drought may have delayed or diminished the response to release. The competitive influence of understory
dominant mountain laurel at stand age 14 appears to be slight compared to the influence of other competing hardwood vegetation.
48. Clinton, Barton D.; Vose, James M. 1996. Effects of Rhododendron maximum L. on Acer rubrum L. seedling establishment.
Castanea. 61(1): 38-45.
Rhododendron maximum L. restricts regeneration of overstory species; however, the mechanisms are poorly understood. Three
treatments were used to examine the effects of R. maximum germination success and survival of Acer rubrum L. under a closed overstory
canopy: (1) R. maximum understory, (2) open understory, and (3) open understory with shade cloth. Shade cloth treatments mimicked the
low light conditions beneath R. maximum while controlling for R. maximum forest floor influences. Soil moisture was significantly lower
under R. maximum than under open or shade cloth treatments. Initially, Acer rubrum survival was similar for open understory and shade
cloth treatments, while germination and survival in R., maximum plots were low. After approximately 20 d, mortality in the shade cloth
treatment increased and survival rates were less than 5% by the end of the sampling period. Survival in the open understory treatment
stabilized at >2X that observed under shade cloth, while percent germination and survival in R. maximum plots were lower than in either
of the other treatments throughout the sampling period. These results suggest that in addition to the light limitation associated with R.
maximum, edaphic effects such as low soil moisture or allelopathic compounds may inhibit Acer rubrum success.
49. Clinton, Barton D.; Vose, James M. 1999. Fine root respiration in mature eastern white pine (Pinus strobus) in situ: the
importance of CO2 in controlled environments. Tree Physiology. 19: 475-479.
We measured seasonal fine root respiration rate in situ while controlling chamber temperature and [CO2]. Atmospheric [CO2] ([CO2] a)
and measured soil [CO2] ([CO2] s) were alternately delivered to a cuvette containing intact fine roots of eastern white pine (Pinus strobus
L.). Respiration rates were consistently higher in [CO2] a than in [CO2] s and were almost three times higher during midsummer.
Respiration rates were immediately reversed after returning to the alternate [CO2] (i.e., [CO2] a à [CO2] s à [CO2] a, and vice versa)
suggesting a direct effect of elevated [CO2] on apparent respiration. Soil [CO2]-based respiration rates decreased with increasing [CO2]
on a dry mass and tissue [N] basis. We conclude that estimates of soil CO2 flux and soil carbon budgets may be improved by more
completely accounting for the rhizosphere microclimate (i.e., soil temperature and [CO 2] s) during measurement of fine root respiration.
50. Clinton, Barton D.; Vose, James M. 2000. Plant succession and community restoration following felling and burning in the
southern Appalachian mountains. In: Moser, W. Keith; Moser, Cynthia F., eds. Fire and forest ecology innovation silviculture and
vegetation management. Tall Timbers Fire Ecology Conference Proceedings, No. 21; 1998 April 14-16; Tallahassee, FL. Tallahassee,
FL. Tall Timbers Research Station. 22-29.
Recent declines in the yellow pine component of pine-hardwood stands in the southern Appalachian Mountains have prompted managers
to increase the use of fire as a Silviculture tool. The fell and burn treatment is designed to remove competing vegetation (hardwoods and
mountain laurel [Kalmia latifolia]) to ensure successful establishment of planted eastern white pine (Pinus strobus). Two years after
burning, mountain laurel had accumulated more biomass than any other species and accounted for 43% of total biomass in year 1 and
20% in year 2. By year 4, mountain laurel ranked fifth (8.9% of total) in total biomass among hardwood species behind Allegheny
serviceberry (Amalanchier arborea, 14.3%), chestnut oak (Quercus prinus, 13.7%), red maple (Acer rubrum, 12.4%), and scarlet oak (Q.
coccinea, 9.3%). Across sites, woody species richness ranged from 19-24 in year 1 and 14-22 in year 4. Species richness varied across
sites and years, and there were substantial changes in the distribution of biomass among species. The introduction of fire allowed the
once dominant pitch pine (P. rigida) to successfully reestablish. On sites, pine accounted for 25% of pretreatment stem density, but <1%
and 2% in the first and fourth growing seasons after burning, respectively. However, in year 1, pines had increased in density 20-fold
compared to pretreatment levels, and by year 4, had maintained a 17-fold increase compared to pretreatment. The use of fire in forest
management has been the subject of considerable criticism. In light of current public concerns over the loss of critical or unique habitats,
fire may gain public support for use as a restoration tool.
51. Clinton, Barton D.; Vose, James M. 2003. Differences in surface water quality draining four road surface types in the southern
Appalachian. Southern Journal of Applied Forestry. 27(2): 100-106.
Improved and unimproved roads can be the primary source of stream sediment in forested watersheds. We assessed differences in
production of total suspended solids (TSS; ppm) from four road surface conditions in a Southern Appalachian watershed: (1) a 2-yr-old
paved surface (P), (2) an improved gravel surface with controlled drainage and routine maintenance (RG), (3) an improved gravel
surface with erosion and sediment control structures installed and routine maintenance (IG), and (4) an unimproved poorly maintained
gravel surface (UG). Variation was high among and within road surface types. The P surface generated the least amount of TSS, which
was comparable to control sites, while the UG surface generated the most. The P surface produced significantly less TSS than the UG
surface, but less than the IG and RG surfaces. Variation among road surface types was related to TSS travel distance below the road,
precipitation amount, time of year, and the existence of functioning erosion and sediment control structures. TSS decreased with travel
distance (P= 81% over 38.5 m, IG= -30% over 30.5 m, RG=-89% over 39.4 m, and UG=-22% over 28.1m). Also in this study we
12
assessed the delivery of total petroleum hydrocarbons (TPH; ppm) from the P surface and found concentrations of <0.5 ppm, which are
will below published USEPA and NC DENRTPH standard for sediment. Paving is an attractive option for reducing maintenance costs
and sediment production and transport; however, levels of TPH from freshly applied asphalt are unknown.
52. Clinton, Barton D.; Vose, James M.; Knoepp, Jennifer D.; Elliott, Katherine J. 2003. Stream nitrate response to different
burning treatments in southern Appalachian forests. In: K.E.M. Galley, R.C. Kilinger, and N.G. Sugihara (eds.). Proceedings of Fire
Conference 2000: The First National Congress on Fire Ecology, Prevention, and Management. Miscellaneous Publication No. 13, Tall
Timbers Research Station, Tallahassee, FL. 174-181.
Southern Appalachian forests are undergoing considerable change due to altered disturbance regimes. For example, fire exclusion has
had a major impact on the structure and function of pine-hardwood ecosystems. Recently, fire has been prescribed for a variety of
applications: 1) stand-replacement in the form of mimicked wildfire, 2) site-preparation as part of a fell-and-burn prescription, and 3)
understory burning for fuels reduction and wildlife habitat improvement. Assessing watershed-scale responses to burning requires
identification of key parameters indicative of changes in structure and function. In the southern Appalachians, nitrogen in the form of
NO3 is a key indicator of ecosystem change or response to disturbance. We compared stream NO 3-N responses among stand-replacement
fires (Winespring Creek and Hickory Branch), a fell-and-burn prescription (Jacobs Branch), and a wildfire in an old-growth deciduous
forest (Joyce Kilmer). Nitrate-nitrogen concentration increased following two of the four fires. Concentrations following the fell-andburn prescription fire increased from <0.01 to a maximum of 0.075 mg L-1 and remained elevated for 8 months. Similarly, stream NO3
concentration increased approximately 2 weeks following the old-growth deciduous wildfire from 0.04 to a maximum of 0.50 mg L-1and
remained elevated for 6 weeks. There were no significant differences in NO3 following one of the stand-replacement fires or between
treatment and control or pre- and post-burn following the other stand-replacement fire due to maintenance of an unburned riparian area.
Although the old-growth deciduous wildfire was essentially an understory burn, the magnitude of stream N response suggests that
unavailable recalcitrant forms of N may have been released during the wildfire, as well as a reflection of the potential inefficiency of oldgrowth forests at sequestering mobilized nutrients. In all cases, hydrologic losses of NO3-N were insignificant with respect to effects on
water quality and site depletion of N.
53. Clinton, Barton D.; Vose, James M.; Swank, Wayne T. 1996. Shifts in aboveground and forest floor carbon and nitrogen pools
after felling and burning in the southern Appalachians. Forest Science. 42(4): 431-441.
Changes in aboveground and forest floor mass, carbon (C), and nitrogen (N) pools were quantified on three sites in the southern
Appalachians 2 yr after felling and burning. Before felling and burning, stands were characterized by sparse overstories and dense
Kalmia latifolia L. understories. Two years after burning, foliar C and N pools had reached 25% and 29% of pretreatment levels,
respectively. Foliar N concentrations were not different from pretreatment values. Standing wood C and N pools were 1% and 2%,
respectively, of pretreatment values. Wood N c-concentrations were significantly higher on two sites, likely related to differences in fire
intensity. Forest floor N content 2 yr after burning was 90% of pretreatment levels, most contained in unconsumed large woody material.
Forest floor mass was significantly lower in the Oil layer and unchanged in the Oe + Oa layers. Forest floor N concentrations were
generally lower after treatment. The site with the least intense fire and the lowest mass loss from the forest floor had the highest forest
floor, foliage, and wood N concentrations 2 yr after burning. Site recovery after felling and burning was a function of fire severity and
the capacity for site-nutrient retention through plant uptake.
54. Clinton, Barton D.; Vose, James M.; Swank, Wayne T.; Berg, Eric C.; Loftis, David L. 1998. Fuel consumption and fire
characteristics during understory burning in a mixed white pine-hardwood stand in the southern Appalachians. Research Paper SRS-12.
Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station: 8 p.
We characterized fire behavior and fuel consumption resulting from an understory prescribed burn in a mixed eastern white pinehardwood stand in the Southern Appalachians. Three stands were used for the treatment. Flame lengths, ranging from 0.3 to 1.5 meters
(m) for backing fires and from 1.2 to 4.5 m for head fires, reached maximum heights where evergreen understory was found. Rates of
spread ranged from 1.8 to 3.0 m per minute for head fires and 0.3 m per minute for backing fires. Fire intensity, measured with ceramic
tiles painted with heat-sensitive paint, varied across stands. Mean peak flame temperature ranged from 129 to 290ºC. Pre-burn mass
totals were similar among stands, except for stand 1, which had substantially greater humus mass than the other stands. Consumption of
litter and humus layers in the forest floor was positively correlated with flame temperature. Small wood (<8 cm diameter) consumption
was not correlated with temperature. Over all stands, 50 percent of the mass in small wood and litter was lost during burning, and 20
percent of the humus layer was consumed. The losses in the humus layer represent about 40 percent more humus mass consumption than
would have occurred in a fell-and-burn treatment. The humus layer is an important nutrient reservoir for plant growth. Maintaining this
layer through careful selection of burning conditions will minimize losses during burning and maintain long-term site productivity.
55. Clinton, Barton D.; Yeakley, J. Alan; Apsley, David K. 2003. Tree growth and mortality in a southern Appalachian deciduous
forest following extended wet and dry periods. Castanea: 68(3): 189-200.
We inventoried two 1-ha plots on opposing watersheds (WS2-WS-S, WS18-WS-N) three times (1983, 1989, 1998) over a 16-year period
to contrast how differing precipitation (P) regimes affect tree mortality. From 1983 to 1989, annual precipitation averaged 16.5% less
than the 64-year mean; from 1989 to 1998, it averaged 12.2% above the mean. In 1989 and 1998, standing crop biomass, above ground
13
net primary productivity, mortality rates and species composition were determined. In 1989, following the dry period, the highest
mortality for canopy tree species was in Carya spp. and Quercus velutina in both watersheds. Following the wet period in 1998, mortality
was highest in Cornus florida in both watersheds, presumably due to the Anthracnose fungus; however, net change in stem density due to
ingrowth was positive for this species in the WS-S watershed (+34%) and negative in the WS-N watershed (-18%). Estimated ANPP for
WS-S was 10 and 1,076 kg ha-1yr-1for the periods 1983-89 and 1989-98, respectively. In contrast, ANPP on WS-N was 679 and 93 kg
ha-1yr-1 for the same periods. Differences in ANPP are due to higher rates of mortality on WS-N compared with WS-S. In this study,
species-specific rates of mortality varied by watershed, and were likely due to microclimate-related increased susceptibility at the species
level to certain proximal causes.
56. Coleman, D.C. 1994. Compositional analysis of microbial communities: is there room in the middle? In: Ritz, K.; Dighton, J.;
Giller, K.E., eds. Beyond the biomass. Chichester, UK: John Wiley & Sons Ltd.: 201-220.
By paraphrasing Feynman, this chapter considers the organization of soil communities over a wide range of scales. Some large surprises
undoubtedly await us as we continue to discover how soil systems function under the increasing onslaught of human and human-induced
activities in all the ecosystems of the world. The magnitude of the impact on soil ecosystems from land-use change will probably
continue to be the dominant force of change, as contrasted to the more indirect ones of global change. The key is to separate the
components of variability into those that inhibit persistence and coexistence; those that promote these and those that are noise. Our
principal concerns, going over more than nine orders of magnitude just within a soil alone, must be to assess the problems of aggregation
and simplification, which has been termed the problem of determining minimal sufficient detail.
57. Coleman, D.C.; Hendrix, P.F. 2000. Invertebrates as webmasters in ecosystems. New York, NY: CABI Publishing: 336 p.
This book will appeal to a wide range of ecologists in basic and applied aspects of ecology internationally. In computing terminology, ‘A
webmaster is one who designs, organizes, and maintains a webpage. The webmaster has a global, not a local perspective. No matter what
language is used, the webmaster facilitates access to the web’ (Aram Rouhani, personal communication). While not imputing purpose in
a human-oriented sense to actions of individual species in ecosystems, we suggest that entire assemblages of invertebrates occupying
many hot-spots in soils, such as the rhizosphere and drilosphere, and other portions of both terrestrial and aquatic ecosystems, assume an
organizing function and, hence, may be considered as ‘webmasters’. This theme emphasizes the centrality of the activities of
invertebrates, which influence ecosystem function far out of proportion to their physical mass in a wide range of ecosystems, particularly
at the interfaces between land and air (litter/soil), water and land (sediments), and in tree canopies and root/soil systems. The webmaster
concept reflects both direct and indirect influences of organismal activities, for example on nutrient dynamics in entire watersheds, and is
thus qualitatively different from the keystone species concept, which relates to impacts of a particular species on other species and
communities in a given habitat. The webmasters concept spans scales ranging from microsites to aspects of global climate change.
58. Coleman, David C. 1999. Book Review. Soil Biology & Biochemistry. 31:1599-1601.
Nitrogen and its fluxes in the biosphere and associated spheres on earth (atmosphere, hydrosphere, lithosphere, and pedosphere) is
proving to be one of the most interesting and problematic of the vital elements necessary for the existence of life. On 3-5 September
1997, the third New Phytologist symposium was held at Lancaster University, to address the anthropogenic aspects of N enrichment:
acidification, climate change, eutrophication, and ozone destruction. Because of the intimate association of nitrogen gases with ozone
depletion, the symposium included that aspect of the oxygen cycle as well.
59. Coleman, David C. 2001. Soil biota, soil systems, and processes. In: Levin, Simon ed. Encyclopedia of Diversity, vol. 5. American
Press. 305-314.
Soil Biodiversity is an intriguing, largely unappreciated facet of global biodiversity. There are many phyla, even “domains,” within soils,
which are largely unseen, making use of the uniquely diverse physicochemical complexity of soils, which is an intersection of mineral,
organic, aquatic, and aerial habitats. Organisms have evolved in soils literally since pre-Cambrian times (more than 600 million years
ago). They are still largely undescribed, and this is particularly true for the prokaryotes, which have awaited the development of new
techniques to characterize them. By linking several organismal groups to major processes in global biogeochemistry, it is proving
possible to appreciate the wide array and diverse nature of soil organism functions in the biosphere.
60. Coleman, David C.; Blair, John M.; Elliott, Edward T.; Wall, Diana H. 1999. Soil invertebrates, chap. 17. In: Robertson, G.
Philip; Coleman, David C.; Bledsoe Caroline S.; Sollins, Phillip, eds. Standard soil methods for long-term ecological research: 349-371.
We consider functional roles, methods for sampling, extraction (including supplies and equipment needed) and characterization of
microfauna (protozoa, rotifers and tardigrades), mesofauna (nematodes, microarthropods and enchytraeids), and macrofauna
(earthworms) in a wide range of sites, comprising the entire LTER network. An extensive bibliography of sampling methods is also
included.
61. Coleman, David C.; Crossley, D.A. Jr. 1996. Fundamentals of soil ecology. San Diego, CA: Academic Press: 205 p.
14
This graduate level text reference is designed to be a bridge between ecologists and soil scientists. There is increasing awareness that soil
is the organizing center for all terrestrial ecosystems. This text examines why this is so, in terms of physics, chemistry, and biology of
soil ecosystems. Biodiversity and global change and the important role soils play in global carbon balance are also discussed.
62. Coleman, David C.; Hunter Mark D.; Hutton, John; Pomeroy, Steven; Swift, Lloyd, Jr. 2002. Soil respiration from four
aggrading forested watersheds measured over a quarter century. Forest Ecology and Management. 157: 247-253.
Soil respiration was measured in four aggrading, forested second-growth watersheds in the southern Appalachians using an identical
method (alkali absorption) at intervals 23 and 24 years apart. Seasonal trends were similar, with mid-summer maxima and winter
minima. Amounts of carbon dioxide evolved were higher in the recent measurements (1995) compared to the earlier ones (1971-1972),
despite similar soil water and temperature regimes. The overall trend across all four watersheds may reflect changes in organic matter
levels and subsequent root growth.
63. Cooper, John E.; Schofield, Katherine A. 2002. Cambarus (Jugicambarus) tuckasegee, a new species of crayfish (Decapoda:
Cambaridae) from the Little Tennessee river basin, North Carolina. Proceedings of the Biological Society of Washington. 115(2): 371381.
Kasyt Cambarus (Jugicambarus) tuckasegee is a new species of streamdwelling crayfish that appears to be endemic to part of the
Tuckasegee River subdrainage of the Little Tennessee River basin in the Blue Ridge province of North Carolina, where currently it is
known from Soco Creek, Raven Fork, and the Oconaluftee River. It seems to share strong affinities only with Cambarus (J.) distans,
which occurs in Kentucky, Tennessee, Alabama, and ostensibly in northwestern Georgia. It is readily distinguishable from this and all
other members of the subgenus Jugicambarus by a combination of characters that includes: a short central projection with a deep sub
apical notch, and a long, caudoproximally directed mesial process, both on the gonopod of the form I male; a very inflated palm and
notably short, stout fingers, all lacking tufts of long, stiff setae; a broad, densely punctuate areola; a rostrum with very thickened,
sometimes cephalically produced margins; and five to seven tubercles or spines on the ventral surface of the carpus.
64. Courant, Paul N.; Niemi, Ernie; Whitelaw, W. Ed. 1997. The ecosystem-economy relationship: insights from six forested LTER
sites. A report to the National Science Foundation. Grant No. DEB-9416809: 89 p.
The debate over forest-management policy in the U.S. often is cast as a choice between jobs and [pick the environmental attribute of
your choice]. The purpose of this paper is neither to rehash nor to characterize these conflicts, but to discuss insights into them that have
emerged from an examination of the forest-economy relationship in different regions of the U.S. Specifically, we examine the foresteconomy relationship associated with six of the Long Term Ecosystem Research (LTER) sites: Bonanza Creek, Alaska; H.J. Andrews,
Oregon; Sevilleta, New Mexico; Coweeta, North Carolina; Northern Temperate Lakes, Wisconsin, and Hubbard Brook, New
Hampshire.
65. Courtney, Gregory W. 1998. A method for rearing pupae of net-winged midges (Diptera: Blephariceridae) and other
torrenticolous flies. In: Proceedings of the Entomological Society of Washington. 100(4): 742-745.
A method for obtaining reared adults of net-winged midges (Diptera: Blephariceridae) is presented. Rocks with attached pupae are
removed from the stream and placed in a container maintained at high humidity. Survival and emergence rates exceeding 60% were
recorded for several species of Nearctic Blepharicera. This method is ideal for associating pupae and adults of blepharicerids and other
torrenticolous flies.
66. Courtney, Gregory W. 2000. Revision of the net-winged midges of the net-winged midges of the genus Blepharicera Macquart
(Diptera: Blephariceridae) of eastern North America. In: Memoirs of the Entomological Society of Washington Number 23. The
Entomological Society of Washington, Washington, D.C. 99 p.
The net-winged midges (Diptera: Blephariceridae: Blepharicera Macquart) of eastern North America are revised to include 16 species.
Seven new species are described: B. caudate, n. sp., B. Chattooga, n. sp., B. corniculata, n..sp., B. magna, n. sp., and B. tuberosa, n. sp.
from the southern Appalachians; B. gelida, n. sp. from the central and southern Appalachians; and B. hispida, n. sp. from the central and
northern Appalachians. Previously unknown life stages of B. capitata Loew, B, cherokea Hogue, B. diminutiva Hogue, and B. separata
Alexander, a species raised from synonymy, are described, and a redescription of adult B. separatea is given. Also provided are an
overview of blepharicerid natural history, keys to larvae, pupae, and adults of all eastern Blepharicera, and brief discussions of the
bionomics and distribution of each species.
67. Crenshaw, C.L.; Valett, H.M.; Webster, J.R. 2002. Effects of augmentation of coarse particulate organic matter on metabolism
and nutrient retention in hyporheic sediments. Freshwater Biology. 47: 1820-1831.
1. Metabolic and biogeochemical processes in hyporheic zones may depend on inputs of coarse particulate organic matter. Our research
focused on how differing quantity and quality of organic matter affects metabolism and nutrient retention in the hyporheic zone of a
first-order Appalachian stream.
15
2. Sixteen plots were established on a tributary of Hugh White Creek, NC, U.S.A. Sediment was extracted and treated with leaves, wood,
plastic strips or remained unamended. Following treatment, sediment was returned to the stream and, approximately 3 months later,
samples were removed from each plot.
3. Aerobic and anaerobic metabolism were measured as the change in O2 and CO2 in recirculating microcosms. At the same time, we
monitored other possible terminal electron accepting processes and changes in nutrient concentrations. Aerobic metabolism was low in
all treatments and respiratory quotients calculated for all treatments indicated that metabolism was dominated by anaerobic processes.
4. Rates of anaerobic respiration and total (combined aerobic and anaerobic) respiration were significantly greater (P < 0.05) in plots
treated with leaf organic matter compared to controls.
5. Addition of leaves, which had a low C: N ratio, stimulated respiration in hyporheic sediments. Anaerobic processes dominated
metabolism in both control and amended sediments. Enhanced metabolic rates increased retention of many solutes, indicating that
energy flow and nutrient dynamics in the subsurface of streams may depend upon the quantity and quality of imported carbon.
68. Crocker, Tracey L.; Hendrick, Ron L.; Ruess, Roger W.; Pregitzer, Kurt S.; Burton, Andrew J.; Allen, Michael F.; Shan,
Jianping; Morris, Lawrence A. 2003. Substituting root numbers for length: improving the use of minirhizotrons to study fine root
dynamics. Applied Soil Ecology. 23: 127-135.
Minirhizotrons provide a unique way to repeatedly measure the production and fate of individual root segments, while
minimizing soil disturbance and the confounding of spatial–temporal variation. However, the time associated with processing
videotaped minirhizotron images limits the amount of data that can be extracted in a reasonable amount of time. We found
that this limitation can be minimized using a more easily measured variable r (i.e. root numbers) as a substitute of root length.
Linear regression models were fitted between root length versus root number for production and mortality of seven sample
datasets of varying tree species and treatments. The resulting r2 values ranged from 0.79 to 0.99, suggesting that changes in
root numbers can be used to predict root length dynamics reliably. Slope values, representing the mean root segment length
(MRSL), ranged from 2.34 to 8.38mm per root segment for both production and mortality. Most treatments did not alter
MRSL substantially, the exceptions being CO2 treatments and a girdling treatment that altered plant community composition
and, consequently, root morphology. The high r2 values demonstrated a robust relationship between variables irrespective
of species or treatments. Once the quantitative relationship between root lengths and numbers has been established for a
particular species–treatment combination, quantifying changes in root number through time should substantially decrease the
time required to quantify root dynamics.
69. Crossley, D.A., Jr.; Coleman, D.C. 1999. Macroarthropods. In: Sumner, Malcom E., ed. Handbook of soil science. CRC Press.
Boca Raton, FL.: C-65-C-70.
The macroarthropods are those large enough to be sampled as individuals, in contrast to the microarthropods, which are sampled by
extraction from a fragment of habitat Although smaller macroarthropods overlap in size with the larger microarthropods, the distinction
between them is practical one, based on method of sampling. A functional difference lies in their impact on soils. Macroarthropods are
capable of restructuring soil profiles or relocating large amounts of soil, whereas microarthropods must take advantage of existing pore
spaces. Two insect groups, the ants and termites, are responsible for major disruptions of soil profiles, while other macroarthropods may
cause some disturbance. Examples include emergence tunnels of periodical cicadas (Insecta: Homoptera) or chimneys made by crayfish
(Crustacea: Decapoda) in marshy areas. The macroarthropods in soil systems are a highly diverse group. Most terrestrial insect orders
contain species that live in the soil at some phase of their life cycle. Transient species (some Lepidoptera) are those that overwinter or
pupate in surficial soil layers. Other temporary residents such as midges and other flies spend their immature stages in the soil but
emerge as adults feed elsewhere. Permanent soil residents, such as predaceous beetles, remain in the soil or on soil surfaces. Spiders
(Araneae) and centipedes (Chilopoda) are numerous and important predators in soil systems. Detritivores include millipedes (Diplopoda)
and sowbugs (Isopoda). Scorpions (Scorpionida) and windscorpions (Solifugae) are important predators in dessert systems.
70. Crossley, D.A., Jr.; Coleman, D.C. 1999. Microarthropods. In: Sumner, Malcom E., ed. Handbook of soil science. CRC Press.
Boca Raton, FL: C-59-C65.
Soil microarthropods are a major fraction of the mesofauna, namely, those arthropods with body widths ranging between approximately
0.1 and 2 mm, and body lengths between 0.2 mm and 10 mm. This scheme of classification, although imprecise, is practical, defined by
the method of sampling. Microarthropods are sampled by collecting a fragment of habitat (e.g., a soil core) and extracting them from it,
macroarthropods are collected by hand sorting, pitfall trapping, or other methods dealing with individuals. Microarthropods are
dominated by two groups; the mites (Acari) and the springtails (Insect order Collembola). Together, mites and springtails account for
about 90% of the microarthropods in most soil systems. Also included in this group, among other, are the Protura, Pauropoda, dipteran
larvae, small spiders, pseudoscorpions, some Homoptera and Coleoptera, and thrips. Immature stages of many insect Orders are
collected from soil samples, and some may be considered microarthropods for purposes of a particular study. These minor groups
typically constitute less than 10% of the total number of microarthropods Numbers of microarthropods in soil systems range upwards to
2000,000 m-2 or more. Forested systems generally support higher microarthropod population densities than do grasslands, deserts, or
agricultural systems, with densities being higher in soils from temperate that tropical forests, and coniferous than deciduous forests. Soils
in agroecosystems may have sparse populations, although numbers increase under conservation tillage management. Together with
16
protozoans, nematodes and other small soil fauna, the microarthropods make up a food web of several trophic levels, driven by energy
sources from decomposing residues and mobilizing nutrient elements.
71. Crossley, D.A., Jr.; Hansen, Randi A.; Lamoncha, Karen L. 1997. Response of forest floor microarthropods to a forest
regeneration burn at Wine Spring watershed (southern Appalachians). In: First Biennial North American Forest Ecology Workshop;
1997 June 24-26; Raleigh, NC: 1-15.
We sampled microarthropods in litter and soil of the Wine Spring watershed on April 2, 1995 before the watershed was burned, again on
May 9, 1995 immediately following burning, and two years later on June 9, 1997. Pre-burn samples revealed a high abundance of mites
(Arachnida: Acari) and collembolans (Insecta: Collembola). Oribatid (Acari: Oribatei) mites were numerous and species-rich. Overall,
112 species of oribatids were identified. The fauna was similar to that described for watersheds at the Coweeta Hydrologic Laboratory,
North Carolina, though some additional species not record for Coweeta were found at Wine Spring. Groups of microarthropods
responded differently to the burning treatment. Prostigmata (Acari), mostly small and delicate forms, were initially reduced to less than
50% of their pre-burn numbers, but recovered after two years. Mesostigmata (Acari) mostly survived the immediate burn but were
reduced two years later. Most species of oribatids survived the initial effects of the burn, but numbers were reduced by 55% and species
richness by 20%. Over the following two years, the oribatid fauna continued to decline to 28% of pre-burn abundance and 70% of preburn species richness. The mosaic nature of the burn left refugia from which microarthropods may re-invade heavily burned areas, once
litter layers become restored.
72. Curtin, Matt. 2002. Water quality effects on fish communities. In: Proceedings land use and biodiversity on the Highlands Plateau.
A Carolina environmental program report; 2002 December 13; Highlands, NC. Highlands, NC. Highlands Biological Station: 7-24.
Development pressures in the Southern Appalachian s pose an increasing threat to the water quality of the region’s numerous rivers and
streams. In this region, humans rely on clean surface water for consumption as well as recreational uses. For example, tourism is the
most important industry in the region, and many businesses depend on clean water and healthy populations of fish and wildlife. In
addition to human uses, the region supports extremely high aquatic species diversity. Many native species, however, are being lost due to
anthropogenic degradations of water quality. River ecosystems are severely threatened and represent key areas for loss of biodiversity
(Sala et al., 2000). Loss of species results in less resilient ecosystems, as a single species may depend on several others as sources of
food, population control, or habitat modification.
73. D'Angelo, Donna J.; Gregory, Stanley V.; Ashkenas, Linda R.; Meyer, Judy L. 1997. Physical and biological linkages within a
stream geomorphic hierarchy: a modeling approach. Journal of the North American Benthological Society. 16(3): 480-502.
Geology and precipitation interact to determine the geomorphology of a stream basin. We propose that stream geomorphology in turn
interacts with sunlight, air temperature, precipitation, and geology to produce a distribution of environmental drivers that is largely
responsible for determining the distribution of organisms in streams. GEOMOD, a physically explicit stream ecosystem model, was
designed to examine this proposal. The model has a geomorphically based hierarchical structure with basin, reach, and channel-unit
levels of resolution. We used GEOMOD: 1) to simulate annual cycles of the biota in 3 rd- and 5th-order stream sections at the basin level
of resolution and 2) to predict organism’s distributions at the reach and channel-unit level of resolution. Stream physical structure and
the 4 environmental drivers were the only factors that differed among the sites. Data from two 150-m sections of 3rd-order Mack Creek
and from a 1.5-km section of 5th-order Lookout Creek in the Cascade Mountains of Oregon were used to parameterize the physical
structure and initial standing crops and calibrate the drivers. Uniform parameters were determined by curve fitting. GEOMOD simulated
annual magnitudes and cycles for abiotic and biotic variables in Mack and Lookout creeks. With explicit parameterization of reach and
channel-unit sequences, GEOMOD also predicted the distribution of organisms among channel units and reaches. Fish distributions were
accurately predicted at the reach scale, while algal-invertebrate interactions and scoring effects became clear only when examined at the
channel-unit level. These results demonstrate that organism distributions and interactions in highly structured streams such as those in
the Pacific Northwest region of the USA can be effectively simulated with a physically explicit model. Although more complicated to
design and parameterize than a uniform physical representation, a physical explicit model can be tailored to represent a wide variety of
stream types.
74. D'Angelo, D.J.; Webster, J.R.; Gregory, S.V.; Meyer, J.L. 1993. Transient storage in Appalachian and Cascade Mountain
streams as related to hydraulic characteristics. Journal of the North American Benthological Society. 12(3): 223-235.
Hydraulic characteristics were measured in artificial streams and in 1 st. - to 5th.-order streams in the Appalachian and Cascade mountains.
Appalachian Mountain stream sites at Coweeta Hydrologic Laboratory, North Carolina, were on six 1 st-order streams and 1st- through
4th.-order gradient of Ball Creek-Coweeta Creek. Cascade Mountain sites were located on constrained and unconstrained reaches of
Lookout Creek, a 5th-order stream in H.J. Andrews Experimental Forest, Oregon. At each site, a tracer solution (chloride or rhodamine
WT) was released for 30-180 min and then discontinued. At the downstream end of the release site, the resulting rise and fall of the
tracer concentration was measured. These data, along with upstream concentration and measured widths and depths, were used in a
computer model to estimate several hydraulic parameters including transient storage and lateral inflow. Estimated transient storage zone
size (As) ranged from near zero in artificial streams to 2.0 m2 in 5th-order streams. As was largest relative to surface cross-sectional area
(A) at 1st-order sites where it averaged 1.2 X A, compared with 0.6 X A and 0.1 X A in unconstrained and constrained 5th-order sites,
17
respectively. Where measured, lateral discharge inputs per meter of stream length ranged from 1.9% of in stream discharge in 1st-order
streams to 0.05% of in stream discharge at 5th-order sites. Our results show that surface water exchange with storage zones is rapid and
extensive in steep headwater streams and less extensive but still significant at 3 rd- through 5th-order sites. An understanding of
relationships between stream morphology, storage zone size, and extent of interactions between surface and subsurface waters will assist
comparisons of solute dynamics in physically diverse streams.
75. Darke, Arlene K.; Walbridge, Mark R. 2000. Al and Fe biogeochemistry in a floodplain forest: implications for P retention.
Biogeochemistry. 51:1-32.
We examined spatial and temporal variations in soil chemistry in a floodplain forest landscape to determine the effects of flooding on
aluminum (Al) and iron (Fe) oxide biogeochemistry and inorganic phosphorus (P i) sorption capacity. When previously sorbed P i was
considered, the sorption capacities of floodplain and adjacent upland soils were comparable, suggesting that floodplain soils represent a
second line of defense protecting downstream aquatic ecosystems from agricultural run-off. P i sorption capacity was highly correlated
with oxalate-extractable Al (Alo) (rs= 0.78); Alo and percent organic matter (OM) were also highly correlated (rs=0.72), suggesting the
importance of OM-Al complexes in these soils. The correlation of oxalate-extractable Fe (Feo) with OM (rs = 0.64) was improved (rs=
0.80) by removing lower elevation (swale) soils, suggesting that flooding inhibits the association of Fe o with OM. Fe oxide crystallinity
decreased during seasonal flooding, but total extractable Fe did not change significantly. Fe solubilized during flooding was either
replaced by sediment deposition (252 ± 3 mmol kg ˉ¹ yr ˉ¹), and/or reprecipitated locally. Al oxide crystallinity also decreased during
flooding due to a significant decline in NaOH-extractable Al (AlN). AlN concentrations subsequently returned to pre-flooding levels, but
sediment Al inputs (57-± 3-mmol kg ‫־‬¹ yr ˉ¹), were insufficient to account for this recovery. Observed Fe transformations suggest the
importance of flooding-induced declines in soil redox potential to Fe biogeochemistry; observed Al transformations suggest the
importance of complexation reactions with soil OM to Al biogeochemistry in this floodplain forest.
76. Davis, Jon Paul; Haines, Bruce; Coleman, David; Hendrick, Ron. 2004. Fine root dynamics along an elevational gradient in the
southern Appalachian mountains, USA. Forest Ecology and Management. 187: 19-34.
Attributes of fine roots (<2.0 mm diameter) were quantified in five southern Appalachian plant communities along an elevation gradient.
These Attributes include the seasonal dynamics of fine root mass and length, the depth distribution of fine roots, fine root width and,
most importantly, the annual appearance and disappearance of fine roots. The principal objectives of this study were two-fold: (1) to
compare these attributes of fine roots between plant communities and (2) to compare the results of the two methods used to quantify the
attributes: (1) harvesting roots from forest soil with soil cores and (2) photographing roots growing against the windows of minirhizotron
boxes. The plant communities that were sampled are characteristic of the region and are designated as follows from lowest elevation
(782 m) to highest elevation (1347 m): (1) xeric ridge, (2) hardwoods, (3) low elevation mixed oak, (4) high elevation mixed oak, and (5)
northern hardwoods. Fine root mass varies seasonally in this temperate region with lowest and highest mass in the spring and autumn,
respectively, Fine root mass and fine root mass appearance were lowest in the cove hardwood community and highest in the low
elevation mixed oak community. The total length of fine roots was highest in the xeric ridge community and lowest in the low elevation
mixed oak community. The high total root length in the xeric ridge community was due to the presence of an exceptionally dense mat of
very fine roots found there. The width of these roots was significantly less than that of roots on all other plots. Subsequent regression
illustrates tow strong patterns in the data. First, fine root mass, fine root mass appearance and leaf production were positively correlated.
Second, fine root length and soil moisture were negatively correlated. The accumulation of root mass in these communities was linked to
overall site productivity and the development of root length in response to moisture stress. Only the timing of root growth initiation was
related to elevation and the associate parameter of soil temperature. The best estimates of fine root appearance and disappearance were
generated by harvesting roots rather than photographing them. Some methodological problems with root photography implemented in
this study are addressed.
77. Davis, Rickie J.; Guynn, David C., Jr.; Hyder, Bryan D. 1994. Feasibility of using tribromoethanol to recapture wild turkeys.
Wildlife Society Bulletin. 22(3): 496-500.
TBE (tribromoethanol), a drug added to shelled corn bait, was used to capture wild turkeys for measurement and attachment of tracking
radio transmitters. Response to TBE was noted for forty birds previously captured using TBE. Eighteen birds returned to bait sites, but
only 4 took the treated bait and only in the year after initial capture. Experienced birds were less likely to take the bait and were observed
warning other birds after sampling the treated bait. Six mortalities occurred due to overdosing when part of the flock refused the bait.
TBE is not recommended for retrapping of wild turkey.
78. de Steiguer, Joseph E.; McNulty, Steven G. 1998. An integrated assessment of climate change on timber markets of the southern
United States. In: Mickler, Robert A.; Fox, Susan, eds. The productivity and sustainability of southern forest ecosystems in a changing
environment. Ecological Studies, vol. 128. New York, NY: Springer-Verlag: 809-822.
Seldom are the biological and economic sciences combined to assess the impact of environmental stress on forest structure and human
supply and demand for forest products. Across the southern United States, forest timber and pulpwood rank as either the first or second
most important agricultural crop for most states. Additionally, timber from this region supply the country with a third of the total needed
timber supply, and this percentage is expected to increase during the next century. Pressures on water supplies are also expected to
18
increase during the next century as the population continues to migrate to the southeastern US. Improved understanding of
environmental stress impacts on regional forest productivity and hydrology are needed to assure sound management and availability of
these resources in the 21st century. This paper examines the impact of five climate change scenarios on southern US forest productivity,
harvest, and change in consumer surplus. The impacts were highly correlated with the climate scenario that was input to the model. The
UKMO scenario predicted the largest climate change and produced the largest reduction forest productivity and consumer surplus.
79. Diamond, Seth J.; Giles, Robert H., Jr.; Kirkpatrick, Roy L.; Griffin, Gary J. 2000. Hard mast production before and after the
chestnut blight. Southern Journal of Applied Forestry. 24(4): 196-201.
We estimated hard mast production of a Southern Appalachian forest for two 10 yr intervals: one before and one, 35 yr after, the
chestnut blight fungus (Cryphonectria parasitica) (Murr.) Barr, had killed all mature chestnut trees. The basal area of hard mastproducing trees in the postblight forest was 28% less than in the preblight forest. The estimate of hard mast output was 34% less after the
chestnut blight. Postblight production was less than preblight production for 8 of 10 yr. During 5 of these years, postblight production
was only 5–27% of preblight production. Annual preblight mast production was relatively stable, whereas annual postblight production
fluctuated substantially. Our findings suggest that the loss of mature chestnuts (Castanea dentata) markedly reduced the Southern
Appalachian forest's carrying capacity for certain wildlife species.
80. Dlamini, Eunice T.; Williams, Arthur L.; Dashek, William V.; Swank, Wayne T.; Vose, James M. 1994. Protein contents of
ozone- and air-fumigated Pinus strobus needles. In: Llewellyn, Gerald C.; Dashek, William V.; O'Rear, Charles E., eds. Biodeterioration
4: mycotoxins, wood decay, plant stress, biocorrosion, and general biodeterioration. New York, NY: Plenum Press: 379-390.
Previous research has shown that a level of amino acids in leaves of certain plants is stress-related. We examined the potential use of
foliar protein content as an indicator of ozone (O3) stress. The ethanol-insoluble protein contents of foliage were analyzed for seedlings
grafted from 30-yr old Pinus strobus trees following exposure to different concentrations of O3. Analysis of foliage exposed to charcoalfiltered air, 100 ppm and 200 ppm O3, showed that substantially elevated O3 levels (200 ppm) are required to show a statistically
significant reduction in total protein content of new foliage. Thus, it appears that total protein is not a sensitive indicator of O3 stress in
this tree species.
81. Dodds, Walter K.; López, Amanda J.; Bowden, William B.; Gregory, Stan; Grimm, Nancy B.; Hamilton, Stephen K.;
Hershey, Annie E.; Marti, Eugenia; McDowell, William H.; Meyer, Judy L.; Morrall, Donna; Mulholland, Patrick J.; Peterson,
Bruce J.; Tank, Jennifer L.; Valett, H. Maurice; Webster, Jackson, R.; Wollheim, Wilfred. 2002. N uptake as a function of
concentration in streams. Journal of North American Benthological Society. 21(2): 206-220.
Detailed studies of stream N uptake were conducted in a prairie reach and gallery forest reach of Kings Creek on the Konza Prairie
Biological Station. Nutrient uptake rates were measured with multiple short-term enrichments of NO3HN dna ‫־‬4+ at constant addition
rates in the spring and summer of 1998. NH4+ uptake was also measured with 15N‫־‬NH4+ tracer additions and short-term unlabeled NH4+
additions at 12 stream sites across North America. Concurrent addition of a conservative tracer was used to account for dilution in all
experiments NH4+ uptake rate per unit area (U1) was positively correlated to nutrient concentration across all sites (r2= 0.41, log-log
relationship). Relationships between concentration and U1were used to determine whether the uptake was nonlinear (i.e., kinetic uptake
primarily limited by the biotic capacity of microorganisms to accumulate nutrients) or linear (e.g., limited by mass transport into stream
biofilms). In all systems, U1 was lower at ambient concentrations than at elevated concentrations. Extrapolation from uptake measured
from a series of increasing enrichments could be used to estimate ambient U1. Linear extrapolation of U1 assuming the relationship
passes through the origin and rates measured at 1 elevated nutrient concentration underestimated ambient U1 by ~3-fold. Uptake rates
were saturated under some but not all conditions of enrichment; in some cases there was no saturation up to 50 µmol/L. The absolute
concentration at which U1 was saturated in Kings Creek varied among reaches and nutrients. Uptake rates of NH4+ at ambient
concentrations in all streams were higher than would be expected, assuming U1 does not saturate with increasing concentrations. At
ambient nutrient concentrations in unpolluted streams, U1 is probably limited to some degree by the kinetic uptake capacity of stream
biota. Mass transfer velocity from the water column is generally greater than would be expected given typical diffusion rates,
underscoring the importance of advective transport. Given the short-term spikes in nutrient concentrations that can occur in streams (e.g.,
in response to storm events), U1 may not saturate, even a high concentrations.
82. Dolloff, C. Andrew; Webster, Jackson R. 2000. Particulate organic contributions from forests to streams: debris isn't so bad.
Chapter 7. In: Verry, Elon S.; Hornbeck, James W.; Dolloff, C. Andrew., eds. Riparian management in forests of the continental eastern
United States. Boca Raton, FL, Lewis Publishers: 125-138. Chapter 7.
Our task in this chapter is to outline what we know about the functions and values of leaves and wood in streams. In doing so we hope
not only to dispel the common misconception that wood debris in streams is undesirable, but also to instill the concept of organic matter
as an asset to be husbanded.
83. Dougherty, P.M.; Whitehead, D.; Vose, J.M. 1994. Environmental influences on the phenology of pine. Ecological Bulletin.
(Copenhagen) 43: 64-75.
19
The phenology of six major timber producing species of pines is discussed. Phenophases that represent large sinks for carbohydrates are
emphasized: height, bole diameter, branch and foliage development, and root growth. The role of environmental factors in altering
initiation; cessation and growth activity of each phenophase is discussed.
84. Eberts, Sandra M.; Schalk, Charles W.; Vose, James; Harvey, Gregory J. 1999. Hydrologic effects of cottonwood trees on a
shallow aquifer containing trichloroethene. In: Hydrological science and technology special issue 4 th. USA/CIS Joint Conference:
Hydrological Issues of the 21st. Century: Ecology, Environment, and Human Health; 1999 November 7-10, San Francisco, CA; St. Paul,
MN. American Institute of Hydrology: 15:115-121.
In April 1996, a field demonstration was begun to evaluate the use of cottonwood trees to help clean up a trichloroethene-contaminated
shallow aquifer (<4 meters below land surface) at the Naval Air Station, Fort Worth, Texas. Transpiration, climate, soil-moisture, and
tree-root data were collected and used to parameterize and validate the hydrologic model PROSPER, which was used to simulate
evapotranspiration for a 12-year period and to determine the trees’ uptake of contaminated water from the saturated zone (aquifer).
Simulated annual evapotranspiration from the combined unsaturated and saturated zones ranges from 25 to 48 centimeters for the period
when the tree plantations have achieved a closed canopy (year 12 and beyond), depending on assumptions regarding climatic conditions,
soil-water availability, and root growth. Simulated annual uptake from the saturated zone for year 12 and beyond ranges from 12 to 28
centimeters. The ground-water flow model MODFLOW was used to simulate the effects of this predicted transpiration on ground-water
flow in the aquifer. Although transpiration from the aquifer is predicted to reach between 50 and 90 percent of the initial volumetric flux
of ground water through the demonstration site, the outflow of contaminated ground water from the site will likely be reduced by only 20
to 30 percent. The discrepancy between predictions for volume of water transpired from the aquifer and the reduction in volumetric
outflow of contaminate ground water can be attributed to a predicted increase in ground water inflow to the site and the release of water
from storage in the aquifer. It may be possible to achieve a greater amount of hydraulic control if additional trees are planted.
85. Eggert, S.L.: Wallace, J. B. 2003. Litter breakdown and invertebrate detritivores in a resource-depleted Appalachian stream.
Archiv fur Hydrobiologie: 156(3): 315-338.
We measured breakdown rates of leaves and small wood for the first three years in a stream in which detrital inputs were excluded for 7
years and in a reference stream located in the Appalachian Mountains of North Carolina, USA. Leaf and wood inputs were excluded
using a gill-net canopy constructed over a 170-m section of stream. We hypothesized that red maple (Acer rubrum) and rhododendron
(Rhododendron maxima) leaf breakdown rates would decline in the litter exclusion stream as shredder production decreased with each
year of litter exclusion. In contrast, we expected faster wood breakdown rates in the litter exclusion stream as microbes and invertebrates
shifted from leaves to wood as their primary organic matter resource. Consistent with our predictions, wood breakdown rates were
significantly faster in the litter exclusion stream. We also found significantly slower processing rates of maple leaves in the litter
exclusion stream compared to the reference stream during years 2 and 3. Slower breakdown rates for red maple leaves in the litter
exclusion stream were associated with lower shredder production and estimated consumption rates in years 2 and 3. Shredder production
and consumption rate estimates were also lower in the exclusion stream for rhododendron leaves, but leaf breakdown rates were not
affected. We also found that shredder production in litterbags was 3-4 x greater than in benthic substrates in the litter exclusion stream.
In contrast, shredder production in litterbags was similar to that in benthic substrates in the reference stream. These differences were
probably due to the relatively low availability of organic matter in benthic substrates in the litter exclusion stream. Our data show
shredders track high quality organic matter resources (leaves) and contribute to their loss rate, illustrating the interdependence of stream
organisms and terrestrial organic matter input.
86. Eggert, Susan L.; Wallace, J. Bruce. 2003. Reduced detrital resources limit Pycnopsyche gentiles (Trichoptera: Limnephilidae)
production and growth. North American Benthological Society: 22(3): 388-400.
Leaf inputs in temperate forest streams may limit caddisfly production because leaf detritus serves both as a food and case-material
resource. We estimated Pycnopsyche gentilis production in a stream experimentally decoupled from its riparian habitat and a reference
stream for 8 y in the southern Appalachians. We also examined laboratory survivorship, growth, and case-building activities of P gentilis
in substrate containing various quantities of leaf material. Pycnopsyche gentilis production declined to 0 within 3 y of the start of litter
exclusion. Abundance, biomass, and production of R gentilis were positively related to leaf litter standing crops. Maximum individual
length of P gentilis was reduced when annual leaf standing crops fell below 25 to 50 g AFDM/m(2). Observations of case construction
for instars removed from their original leaf cases and kept in substrate with low leaf standing crop, showed that P gentilis was capable of
rebuilding a case of available substrate and surviving for 3 to 4 wk before dying of starvation. Survivorship and growth were
significantly greater for larvae reared at high and intermediate leaf standing crops, than at low leaf standing crop. Older instars had
higher survivorship rates but lower growth rates than younger instars in the low litter substrates. Survivorship and growth rates were
lower for some individuals forced to rebuild new cases, indicating an energetic cost associated with case-building activities. Our results
demonstrate that the linkage between terrestrially derived organic matter and production of a caddisfly shredder was a consequence of
food availability.
87. Elliot, William J; Flanagan, Dennis; Laflen, John M. 2002. Predicting peak runoff rates from snowmelt with the WEPP model.
In: 2002 ASAE Annual International Meeting/CIGR XVth World Congress; 2002 July 28-31, Chicago, IL; St. Joseph, MI. America
Society of Agricultural Engineers (ASAE): Paper Number: 02-8009.
20
The WEPP model is a daily runoff and erosion prediction model. We propose to use the WEPP model to predict peak runoff rates from
forested watersheds. We compared Curve Number methods to WEPP prediction methods. Both methods predicted similar 24-hr
precipitation amounts, which were similar to observed values. Both values under predicted 24-hour runoff amounts. WEPP predicted
greater peak runoff rates, but there were insufficient data to determine which method provided a more accurate prediction.
88. Elliott, K.J.; Swank, W.T. 1994. Impacts of drought on tree mortality and growth in a mixed hardwood forest. Journal of
Vegetation Science. 5: 229-236.
The tree and shrub species on a 16-ha watershed in the Coweeta Basin were sampled in 1984 and again in 1991 to determine the effects
of drought on tree species composition and basal area growth. Mortality and radial growth were determined for tree species within three
community types that represent a moisture gradient from moist to dry: cove-hardwoods>mixed-oak>oak-pine. Tree mortality from 1984
to 1991 was 20% and 23% in the cove-hardwoods and mixed-oak communities, respectively, compared to only 12% in the oak-pine
type. With the exception of Oxydendrum arboreum and Robinia pseudoacacia, the oaks had higher percentage mortality than any other
genus. Mortality occurred mostly in the small-size class individuals (<10 cm in diameter) for all species, suggesting that thinning was
still an important process contributing to mortality 29 yr after clearcutting. Although growth of Liriodendron tulipifera was much higher
than growth of either Quercus prinus or Quercus coccinea, growth in Liriodendron was significantly reduced by the 1985-88 drought
and no growth reduction was observed for these two dominant Quercus species during the same time.
89. Elliott, Katherine J.; Boring, Lindsay, R.; Swank, Wayne T. 1998. Changes in vegetation structure and diversity after grass-toforest succession in a southern Appalachian watershed. American Midland Naturalist. 140: 219-232.
To document how species richness and diversity (H') recover from severe large-scale disturbance; we report temporal patterns of species
composition and diversity following grass-to-forest succession from a long-term experiment in the Coweeta Basin, western North
Carolina. The original experiment - clear-cutting, 5 yr of grass cover followed by an herbicide treatment, and abandonment in a Southern
Appalachian mixed deciduous forest - represents the most severe human disturbance in the Coweeta Basin. For several years after
cessation of management, Robinia pseudoacacia quickly sprouted from roots and exceeded the growth rates of other species.
Liriodendron tulipifera increased in density and basal area because of its prolific seedling establishment and rapid growth rate.
Regeneration of large seeded species was mixed - sparse for Quercus rubra and Q. coccinea and nonexistent for Q. prinus and Q.
velutina. In the overstory, density-based H' increased from 1958, before grass conversion, to 15 yr and 28 yr following disturbance. In
contrast, basal area-based H' had significantly declined at 15 yr, then increased at 28 yr. The initial decline in basal area-based H' was
attributed to a decline in evenness of species distribution (J') rather than to a change in species richness. The severe disturbance increased
the abundance of early successional woody species and of herbaceous genera that tolerate open habitats, such as Erichtites, Phytolacca,
and Erigeron. Shade-tolerant understory ferns and herbs such a Polystichum acrostichoides, Dennstaedtia punctilobula, Galium
latifolium, and Viola cucullato gradually became more abundant. The 28-yr-old forest of WS 6 had much lower species richness than the
adjacent reference watersheds, but more than threefold higher density.
90. Elliott, Katherine, J.; Boring, Lindsay, R.; Swank, Wayne, T. 2002. Aboveground biomass and nutrient accumulation 20 years
after clear-cutting a southern Appalachian watershed. Canadian Journal of Forest Research. 32: 667-683.
In 1975, we initiated a long-term interdisciplinary study of forest watershed ecosystem response to clear-cutting and cable logging in
watershed 7 at the Coweeta Hydrologic Laboratory in the southern Appalachian Mountains of North Carolina. This paper describes ≈20
years of change in species composition, aboveground biomass, leaf area index (LAI), and nutrient pools in the 59-ha mixed hardwood
forest of watershed 7 following commercial clear-cutting in winter 1977. We measured woody species in 24 permanently marked plots
before cutting in 1974 and during subsequent years (1977-1997). By 1997 (≈20 years after cutting), aboveground biomass was 81.7, 96.9
and 85.4 Mg∙ha-1 in the cove hardwood; mesic, mixed-oak; and dry, mixed-oak communities, respectively. Leaf biomass and LAI
accumulated relatively faster than total aboveground biomass in all three communities. By 1984, only 7-8 years after cutting, leaf
biomass and LAI were nearly equal to the amount estimated for the precut forest. In 1997, nitrogen accumulation was 36, 44, and 61%
and phosphorus accumulation was 48, 66, and 59% in the cove-hardwoods; mesic, mixed-oak; and dry, mixed-oak communities of the
corresponding precut communities, respectively. Potassium, calcium, and magnesium accumulations were less than either nitrogen or
phosphorus accumulation.
91. Elliott, Katherine J.; Boring, Lindsay R.; Swank, Wayne T.; Haines, Bruce R. 1997. Successional changes in plant species
diversity and composition after clear-cutting a southern Appalachian watershed. Forest Ecology and Management. 92: 67-85.
Watershed 7, a southwest-facing watershed in the Coweeta Basin, western North Carolina, USA, was clear-cut in 1977. Twenty-four
permanent plots were inventoried in 1974 before cutting and in 1977, 1979, 1984, and 1993 after clear cutting. This study evaluates
changes in species diversity during early succession after clear cutting and differences in overstory tree and ground flora response to
disturbance by clear cutting and their interaction with previous disturbances and subsequent stand development. To quantify species
diversity, we computed Shannon-Weaver's index of diversity and Pielou's evenness index. Woody species diversity remained relatively
stable; however, woody species richness increased in the cove-hardwoods and hardwood-pines, but remained relatively constant in the
mixed-oak hardwoods. Although revegetation was rapid, forest composition has changed through succession. Opportunistic species, such
21
as Liriodendron tulipifera, Robinia pseudoacacia, and Acer rubrum, increased in abundance, whereas Quercus velutina, Carya spp., and
Q. rubra decreased. Ground flora diversity declined in the cove-hardwoods and mixed-oak hardwoods communities, but the decrease in
the hardwood-pines was not significant. The abundance (g biomass m-2) of ground flora was much lower in 1993 than in 1984; 79% less
in the cove-hardwoods, 90% less in the mixed-oak hardwoods, and 79% less in the hardwood-pines. Watershed 7 is apparently in a
transition state between early and late success ional species abundance. Early successional, shade-intolerant species have declined,
whereas late successional, shade-tolerant species are not well established.
92. Elliott, Katherine J.; Hendrick, Ronald L.; Major, Amy E.; Vose, James M.; Swank, Wayne T. 1999. Vegetation dynamics
after a prescribed fire in the southern Appalachians. Forest Ecology and Management. 114: 199-213.
In April 1995, the USDA Forest Service conducted a prescribed burn along with a south-facing slope of southern Appalachian
watershed, Nantahala National Forest, western NC. Fire had been excluded for over 70 years and the purpose of the burn was to create a
mosaic of fire intensities to restore a degraded pine/hardwood community and to stimulate forage production and promote oak
regeneration along a hillslope gradient. Permanent plots were sampled at three locations along a gradient from 1500 to 1700 m. Plot
locations corresponded to three community types: mesic, near-riparian cove (low slope); dry, mixed-oak (mid slope); and xeric,
pine/hardwood (ridge). Before burning (1994-1995) and post-burn (summer, 1995 and summer, 1996) vegetation measurements were
used to determine the effects of fire on the mortality and regeneration of overstory trees, understory shrubs, and herbaceous species.
After the burn, mortality was highest (31%) at the ridge location, substantially reducing overstory (from 26.84 pre-burn to 19.05 m2ha-1
post-burn) and understory shrub (from 6.52 pre-burn to 0.37 m2ha-1 post-burn) basal area. At the mid-slope position, mortality was only
3%, and no mortality occurred at the low slope. Not surprisingly, percent mortality corresponded to the level of fire intensity. Basal area
of Kalmia latifolia, Gaylussacia baccata, and Vaccinium spp. were substantially reduced after the fire, but density increased due to
prolific sprouting. The prescribed fire had varying effects on species richness and diversity across the hillslope gradient. On the ridge,
diversity was significantly increased in the understory and herb-layer, but decreased in the overstory. On the mid slope, no change was
observed in the overstory, but diversity significantly decreased in the understory. On the low slope, no change was observed in the
overstory or understory.
93. Elliott, Katherine J.; Hewitt, Deidre. 1997. Forest species diversity in upper elevation hardwood forests in the southern
Appalachian mountains. Castanea. 62(1): 32-42.
Overstory, shrub-layer, and herb-layer flora composition and abundance patterns in eleven forest sites were studied to evaluate species
diversity and richness before implementing three types of harvest treatments. The sites were within the Wine Spring Creek Watershed
and were classified as high elevation, dry, Quercus rubra-Rhododendron calendulaceum based on McNab and Browning's Landscape
Ecosystem Classification system. Evaluation of species diversity was determined by Shannon-Weiner's index of diversity (H') and
Pielou's species evenness index (J'). Overstory H' based on tree density ranged from 1.62 to 2.50 and H' based on tree basal area ranged
from 0.94 to 2.22. The importance values for woody species showed four species that occurred on all sites accounted for 32 to 84% of
overstory abundance. Shrub-layer H'Density ranged from 0.64 to 2.33 and H'BA ranged from 0.40 to 2.26. Rhododendron calendulaceum
and Castanea dentata were the only species present on all sites and accounted for 28.5 to 92.3% of the shrub-layer abundance. Herblayer H'Density ranged from 1.72 to 3.02 and J'Density was low, between 0.5 and 0.6 on most sites. Herb-layer diversity was determined by a
few dominant species. Although species richness ranged from 51 to 73, seven genera of understory herbs occurred on all sites and
accounted for 50 to 91% of the total density and 27 to 75% of the total cover. Early successional species were well represented at all
sites. Seedling survivorship, germination, and overstory contribution of seeds, caused varied site representation of species. This study
provides base line data for observing variation in species richness and diversity that will result from experimental harvest methods.
94. Elliott, Katherine, J.; Hitchcock, Stephanie L.; Krueger, Lisa. 2002. Vegetation response to large-scale disturbance in a
southern Appalachian forest: Hurricane Opal and salvage logging. Journal of the Torrey Botanical Society. 129(1): 48-59.
Disturbance such as catastrophic windthrow can play a major role in the structure and composition of southern Appalachian forests. We
report effects of Hurricane Opal followed by salvage logging on vegetation dynamics (regeneration, composition, and diversity) the first
three years after disturbance at the Coweeta Hydrologic Laboratory in western North Carolina. The objective of this study was to
compare species composition and diversity of understory and ground layer species was much higher in the H+S forest than in the
undisturbed forest, and abundance increased over time. Percent cover, density, and species richness were significantly higher in the H+S
forest than in the undisturbed forest. In addition, percent cover increased by approximately 85% between 1997 and 1999 in the H + S
plots.
Shannon’s index of diversity (H’) based on percent cover was significantly higher in the H+S forest than the undisturbed forest by the
third year after disturbance. However, there was no significant difference in H’ based on density between H+S forest and undisturbed
forest in either year. In the undisturbed forest, 59 species and 50 genera represented 30 families. The Asteraceae and Lilaceae had the
highest number of species in both sampled forests, with more species of Liliaceae in the H+S plots. Micro-relief created fro pit and
mound topography from uprooting of wind thrown trees, shade from the slash-debris left on site from the salvage logging, and shade
from the remaining overstory trees created a mosaic of environmental conditions. This environmental heterogeneity could be responsible
for the mix of early (shade intolerant) and late (shade tolerant) successional herbaceous species, and a higher species richness and
diversity than the undisturbed forest.
22
95. Elliott, Katherine J.; Swank, Wayne T. 1994. Changes in tree species diversity after successive clearcuts in the southern
Appalachians. Vegetation. 115: 11-18.
A 16 ha watershed in the Coweeta Basin was clearcut in 1939 and 1962. Vegetation was inventoried in 1934 and at about 7-year
intervals to 1991. After the first clearcut, tree diversity remained high until after the second cut. Diversity based on density and basal
area decreased significantly 14 years after the second clearcut and remained low through 1991. Diversity was highest in the early
establishment stage of stand development, then declined at the intermediate stage with canopy closure. Evenness based on basal area
declined more than evenness based on density because basal area of Liriodendron tulipifera increased substantially from 1977 to 1991.
Trends in diversity were due to changes in evenness rather than changes in species richness.
96. Elliott, Katherine J.; Vose, James M. 1995. Evaluation of the competitive environment for white pine (Pinus strobus L.) seedlings
planted on prescribed burn sites in the southern Appalachians. Forest Science. 41(3): 513-530.
We evaluated the competitive environment around planted white pine (Pinus strobus L.) seedlings and monitored the response of
seedling growth to competition from naturally regenerating herbaceous and woody species for 2 yr after prescribed burning. We
evaluated the ability of distance-independent and distance-dependent competition indices to predict resource availability, determined if
white pine seedlings responded to resource reduction by competitors, and identified species-specific contributions to the competitive
environment through canonical correspondence analysis (CCA). Distance-independent measures of competition were not as well
correlated with pine seedling growth, as were distance-dependent measures. In 1991, competition was less important in 1991 than in
1992, and ordinating the species with CCA failed to improve the predictability of the competitive environment. By 1992, competition
became more important, and individual species had differing effects on pine growth; we found that light was the most important resource
limiting diameter growth and that the tall tree species were responsible for reduced light availability to pine seedlings.
97. Elliott, Katherine, J.; Vose, James M.; Clinton, Barton D. 2002. Growth of eastern white pine (Pinus strobus L.) related to forest
floor consumption by prescribed fire in the southern Appalachians. Southern Journal of Applied Forestry. 26(1): 18-25.
Chainsaw felling, burning, and planting of eastern white pine (Pinus strobus L.) have been prescribed on degraded pine/hardwoods
stands in the southern Appalachians to improve overstory composition and productivity. He desired future condition of the overstory is a
productive pine/hardwood mixture, with white pine, which is resistant to southern pine beetle (Dendroctonus frontalis), as the dominant
pine. We evaluated the growth of white pine planted after fell-and burn treatments through eight growing seasons after planting on three
sites that differed in their fire characteristics and carbon and nitrogen losses. The three sites (JE, JW, and DD) differed in heat
penetration and forest floor consumption. Although very little consumption of the Oe+Oa humus layer occurred during burning,
consumption of the Oi litter layer was 94%, 94%, and 63% at JE, JW, and DD, respectively. Corresponding to the forest floor layer
consumption (Oi and Oe+Oa combined), 46% of forest floor N was lost at JE, 45% of forest Floor N was lost at JW, and less than 0.1%
of the forest floor N was lost at DD. Biomass and density of woody competitor species were not significantly related to white pine size
or growth. By the eighth growing season, no differences in white pine size or growth were detected between JE and JW, but DD had
significantly smaller white pine trees. The size difference between DD and the other two sites was attributed to the replanting of
seedlings at DD in 1992. However, relative growth rate (RGR) was significantly higher on DD in 1998 than the other two sites. Eight
growing seasons after planting, white pine growth was negatively related to percent Oi layer consumed on the JE and JW sites. We also
found significant relationships between white pine RGR and percent Oi consumed using data from all three sites. Although fire severity
had a long-term effect on pine growth, fire severity was considered low overall on these sites because there were limited losses from the
forest floor Oe+Oa layer. However, white pine increment and RGR were significantly related to percent forest floor Oi mass and N loss.
This loss of site N capital could have a significant negative effect on growth of planted white pine over the long term.
98. Elliott, Katherine J.; Vose, James M.; Swank, Wayne T. 2000. Fire as a silvicultural tool to improve southern Appalachian pinehardwood stands. In: Moser, W. Keith; Moser, Cynthia F., eds. Fire and forest ecology: Innovative silviculture and vegetation
management. Tall Timbers Fire Ecology Conference Proceedings, No. 21. Tallahassee, FL, Tall Timbers Research Station: 198.
Historically, fire was an integral part of the disturbance regime of southern Appalachian forests and defined their natural structure and
composition. In particular, mixed pine-hardwood forest types occupying dry ridge sites (primarily composed of Pinus rigida and
Quercus prinus in the overstory and Kalmia latifolia in the understory) are thought to be highly dependent on high-intensity fires for
their maintenance. Fire suppression and the limited occurrence of intense natural fires in xeric pine-hardwood forests have promoted the
dominance of hardwoods, and the pine component has been in a state of decline for about 2 decades. We have initiated research on the
use of prescribed “stand-replacement” fires to restore degraded pine-hardwood stands. In this application, the objective of the fire is to
produce a high-intensity fire, a simulated wildfire, sufficient to produce seedbed conditions for pine seed germination and reduce Kalmia
latifolia vigor to allow for seedling establishment. This approach has only recently been applied in the southern Appalachians, and very
little is known about ecosystem responses to this prescription. In April 1995, the U.S. Department of Agriculture, Forest Service
conducted a prescribed burn along a south-facing slope of a southern Appalachian watershed, Nantahala National Forest, in western
North Carolina. Fire had been excluded for >70 years, and the purpose of the burn was to create a mosaic of fire intensities to restore a
degraded pine-hardwood community and to stimulate forage production and promote oak regeneration along a hillslope gradient. Our
preliminary results indicate that the prescribed fire increased pine regeneration and created a mix of species comparable to wildfirederived communities. This paper will discuss the advantages, disadvantages, and unknowns associated with this treatment.
23
99. Elliott, Katherine, J.; Vose, James M.; Swank, Wayne T.; Bolstad, Paul V. 1999. Long-term patterns in vegetation-site
relationships in a southern Appalachian forest. Journal of the Torrey Botanical Society. 126(4): 320-334.
We used permanent plot inventories from 1969-1973 and 1988-1993 to describe forest species distribution patterns of the Coweeta
Hydrologic Laboratory, a 2,185 ha basin in western North Carolina, USA. We used canonical correspondence analysis to explore the
vegetation-site patterns for the 1970s and 1990s inventories combined. Site variables were determined by direct measurements or
calculated by digital geographical information system mapping methods. Site variables were percent slope, elevation, terrain shape,
precipitation, modified azimuth, soil organic matter content, soil depth, soil clay content, depth of A-horizon, potential solar radiation,
and mean temperature during the growing season. Fifty percent of the variation in the vegetation distribution was explained by the site
variables used in the canonical correspondence analysis. Soil organic matter, terrain shape, and elevation were the variables most
strongly related to vegetation distribution. Species associated with convex terrain (upper slopes and ridges), such as Pinus rigida,
Quercus coccinea, and Quercus velutina, decreased in abundance from the 1970s to the 1990s; species associated with soils having high
organic matter content and deep A-horizons, such as Liriodendron tulipifera, Rhododendron maximum, and Tsuga canadensis increased
in abundance. Individual species responded differently to site gradients. For example, Acer rubrum, Quercus prinus, Oxydendrum
arboreum, and Nyssa sylvatica were located in the center of the ordination space (i.e., their occurrence was not related to any of the site
variables), which suggests that these species are habitat generalists.
100. Elliott, Katherine J.; White, Alan S. 1994. Effects of light, nitrogen, and phosphorus on red pine seedling growth and nutrient
use efficiency. Forest Science. 40(1): 47-58.
Growth and nutrient use efficiency were determined for red pine (Pinus resinosa Ait.) seedlings grown at various levels of light,
nitrogen, and phosphorus. Nutrient use efficiency was estimated for nitrogen (NUE) and phosphorus (PUE) and was calculated as
biomass production divided by total nutrient content. Seedlings grown in high light had four to five times more biomass than those in the
low light treatment. Nitrogen supply had a significant effect on total biomass as well as other biomass components. Phosphorus supply
did not have a significant effect on any of the biomass components. NUE and PUE decreased with increased supply of N and P,
respectively. The results of this study suggest that red pine seedlings can adjust their nutrient use efficiency, particularly for N, when
light and nutrient availability are varied. NUE was highest with high light and low N-high P supply in nutrient solutions.
101. Fausch, Kurt D.; Taniguchi, Yoshinori; Nakano, Sihigeru; Grossman, Gary D.; Townsend, Colin R. 2001. Flood
disturbance regimes influence rainbow trout invasion success among five Holarctic regions. Ecological Applications. 11(5): 1438-1455.
There is growing awareness that predicting biological invasions will require the development of conceptual models for specific taxa at
appropriate scales. Salmonids are ideal taxa for testing factors that influence invasions, because large numbers have been introduced
worldwide for long periods and their ecology is well known. We evaluated the hypothesis that, among regions with suitable water
temperatures, environmental resistance from flood disturbances that wash away trout fry strongly influence invasion success of rainbow
trout (Oncorhynchus mykiss), the most widely introduced fish species. We predicted that flow regimes in regions where rainbow trout
invasions are successful would match those in their native range and would differ from those in regions where invasions are moderately
successful or failed. We tested six specific predictions about how timing, predictability, frequency, duration, and annual variability of
floods, as well as timing of low flows, will differ relative to timing of rainbow trout fry emergence among five Holarctic regions.
Analysis of hydrologic regimes for eight rivers each in the native range (Pacific Coast) and four regions where rainbow trout invasions
varied from highly successful (Southern Appalachians) to moderate (Colorado, USA, and Hokkaido Island, Japan) or failed (Honshu
Island) showed that winter flooding and summer low flows in Pacific Coast rivers that favor spring emergence of rainbow trout were
closely matched by Southern Appalachian flow regimes. In contrast, the other three regions had spring or summer flooding that
hampered rainbow trout recruitment to different degrees, and winter low flows. Rainbow trout invasion success was best explained by a
match between timing of fry emergence and months of low flood probability. Alternatively, cold-water temperatures, which hamper
reproduction, and biotic interactions with brown trout (Salmo trutta) and whirling disease parasites may account for low invasion success
in European regions. However, differences in genetic makeup of donor stocks and propagule pressure are unlikely mechanisms to
explain invasions. Understanding how abiotic disturbances interact with timing of critical life history events to limit nonnative species
will help ecologists develop more robust theories to predict invasion success.
102. Flebbe, Patricia A. 1999. Trout use of woody debris and habitat in Wine Spring Creek, North Carolina. Forest Ecology and
Management. 114: 367-376.
Wine Spring Creek basin, in the mountains of North Carolina's Nantahala National Forest, is an ecosystem management demonstration
site, in which ecological concepts for management and restoration are tested. Large woody debris (LWD) is an important link between
streams and the adjacent riparian forest, but evidence for the connection between LWD and trout in southern Appalachian streams is
limited. Woody debris loadings, trout habitat, and brook trout and rainbow trout were inventoried for the entire 9.8 km that trout occupy
in Wine Spring Creek. Compared to two reference streams in North Carolina old-growth forests, Wine Spring Creek had less LEWD,
evidence of conditions associated with mid-successional riparian forest. More units in Wine Spring Creek lacked LWD altogether and
accumulations of two or more pieces of LWD were less common than was the case in the reference watersheds. On average, about 71%
of pools and riffles in Wine Spring Creek were occupied by trout, compared to about 90% in reference streams. Trout nearly always
24
occupied pools with at least two pieces of LWD, but rates of occupancy for pools with one or no LWD pieces and riffles were unusually
low compared to reference streams. Habitats on the lower and middle reaches on the main stem of Wine Spring Creek had highest trout
numbers and were nearly always occupied by trout. In these reaches, riparian ages were older and stream habitat had abundant LWD or
boulder substrate. Upper reaches of Wine Spring Creek and its tributaries, however, were characterized by less mature riparian forest,
less LWD and little boulder substrate, low rates of trout occupancy, and lower trout numbers. These conditions are the basis for an LWD
addition experiment in headwater reaches.
103. Flebbe, Patricia A.; Harrison, Jim; Kappesser, Gary; Melgaard, Dave; Riley, Jeanne; Swift, Lloyd W., Jr. 1996. Status of
aquatic resources. In: Southern Appalachian man and the biosphere (SAMAB). The southern Appalachian assessment aquatics technical
report. Report 2 of 5. Atlanta, GA: U.S. Department of Agriculture, Forest Service, Southern Region: 15-63. Chapter 2.
The charter of the Southern Appalachian Assessment was to assemble and analyze available information to answer questions about the
status and trends of resources in this ecologically complex region. The Assessment was a multiagency effort, sponsored by the Southern
Appalachian Man and the Biosphere Cooperative. The question for Chapter 2 of the Aquatic Technical Report was: "What are the
current status and apparent trends in aquatic resources within the Southern Appalachian assessment area?" Chapter 2 begins with an
assessment of the hydrography of the region. The extent and condition of streams, rivers, and lakes are summarized and the potential
sensitivity of streams to acid deposition mapped. Lists are given for threatened, endangered, special concern, and other restricted
population aquatic species. The status of wild trout populations and the integrity of fish and benthic invertebrate communities are
assessed.
104. Flebbe, Patricia A.; Holcomb, Jack; Harrison, Jim; Swift, Lloyd W., Jr. 1996. Evaluation of the assessment. In: Southern
Appalachian man and the biosphere (SAMAB). The Southern Appalachian assessment aquatics technical report. Report 2 of 5. Atlanta,
GA: U.S. Department of Agriculture, Forest Service, Southern Region: 133-140. Chapter 7.
The charter of the Southern Appalachian Assessment was to assemble and analyze available information to answer questions about the
status and trends of resources in this ecologically complex region. The Assessment was a multiagency effort, sponsored by the Southern
Appalachian Man and the Biosphere Cooperative. Chapter 7 of the Aquatic Technical Report integrates the findings from other chapters
to estimate future trends in population growth and water quality, interactions between mining and atmospheric deposition impacts, and
the potential refuges for aquatic plants and animals. Difficulties in acquiring data for the current assessment and research needs to
provide data for future assessments are identified.
105. Ford, W. Mark; Menzel, Michael A.; McCay, Timothy S.; Gassett, Jonathan W.; Laerm, Joshua. 2000. Woodland
salamander and small mammal responses to alternative silvicultural practices in the southern Appalachians of North Carolina. In:
Proceedings annual conference southeast association of fish and wildlife agencies. 2000 October 28-November 1, Baton Rouge, LA.
Southeast Association of Fish and Wildlife. 54: 241-250.
The effects of 2 years post-treatment of group selection and 2-aged timber harvests on woodland salamanders and mammals were
assessed on stands in high elevation, southern Appalachian northern red oak (Quercus rubra) - flame azalea (Rhododendron
calendulaceum) communities, in the Nantahala National Forest. We collected 4 salamander species and 10 small mammal species. We
detected no difference in woodland salamander relative abundance between timber harvests and uncut (control) stands. Similarly,
relative abundance of all small mammal species, except masked shrews (Sorex cinereus), was unaffected by timber harvest. Masked
shrew relative abundance was greater post-harvest in 2-aged harvest stands than in-group selection harvest stands or uncut stands. For
masked shrews, these high elevations, 2-aged harvests may have provided an optimal mix of residual overstory shading, dense shrublayer shading from new regeneration, and abundant downed coarse woody debris. Alternative silvicultural practices, such as group
selection harvest and 2-aged harvests are compatible with goals of providing timber production without altering small mammal and
woodland salamander assemblages on the Wine Spring Creek Ecosystem Management Project area.
106. Ford, W. Mark; Menzel, Michael A.; McCay, Timothy S.; Laerm, Joshua. 2001. Contiguous allopatry of the masked shrew
and southeastern shrew in the southern Appalachians: Segregations along an elevational and habitat gradient. The Journal of the Elisha
Mitchell Scientific Society. 117 (1): 20-28.
Southeastern shrew (Sorex longirostris) and masked shrew (Sorex cinereus) distributions converge in the southern Appalachians. A
306,454-pitfall-trapnight survey in Alabama, Georgia, North Carolina, and South Carolina documented the presence of southeastern
shrews in the Cumberland Plateau Ridge and Valley, Upper Piedmonts, and Blue Ridge physiographic provinces. Southeastern shrews
occur at low elevations (mean = 524.9 m), primarily in xeric upland hardwood, mixed pine (Pinus spp.) -hardwood, and pine forests.
Masked shrews only occur in the Blue Ridge at high elevations (mean = 1,069.6 m), primarily in mesic cove hardwood, northern
hardwood, and montane streamside forests. Upper elevation limits of southeastern shrew and lower elevational limits of masked shrew
show an inverse relation with latitude relative to shrew collections from farther north along the Appalachians. Southeastern shrews and
masked shrews are allopatric in the southern Appalachians except in the Blue Ridge where the species exhibit contiguous allopatry,
based on elevation and habitat associations.
25
107. Ford, William M.; Menzel, M. Alex; McGill, David W.; Laerm Joshua; McCay, Timothy S. 1999. Effects of community
restoration fire on small mammals and herpetofauna in the southern Appalachians. Forest Ecology and Management. 114: 233-243.
As part of the Wine Spring Creek ecosystem management project on the Nantahala National forest, North Carolina, we assessed effects
of a community restoration fire on small mammals and herpetofauna in the upper slope pitch pine stands, neighboring midslope oak
stands and rhododendron dominated riparian areas during 1995 and 1996. Using drift-fence arrays with pitfalls and snap trapping, we
collected these small mammals: masked shrew, smoky shrew, water shrew, pygmy shrew, northern short-tailed shrew, deer mouse,
white-footed mouse, golden mouse, southern red-backed vole, pine vole, and woodland jumping mouse. Herpetofauna collected from
drift-fence arrays and time-constrained searches included: eastern newt, seepage salamander, mountain dusky salamander, Blue Ridge
two-lined salamander, spring salamander, Jordon's salamander, wood frog, five-lined skink, eastern garter snake, and northern ring neck
snake. Prior to the prescribed community restoration fire in the spring of 1995, there were no significant differences in small mammal or
herpetofauna collections between burned and control areas. Post-treatment in 1995 and 1996, showed no significant differences among
collections of most species between burned and control areas. Slope position accounted for more variation among the species of greatest
abundance than did burning. Concern for the effects of prescribed fire as a management tool on small mammals and herpetofauna in the
southern Appalachians seems unwarranted.
108. Freeman, Mary C.; Grossman, Gary D. 1992. A field-test for competitive interactions among foraging stream fishes. Copeia 3:
898-902.
We tested for competitive interactions among midwater stream fishes inhabiting small southern Appalachian streams. We directly
observed fish foraging activity by snorkeling, and tested for significant differences in arrival, departure and feeding rates for the rosy
side dace Clinostomus funduloides foraging in single-species groups compared to multi-species groups with the same numbers of dace.
Observations lasted for 25-40 min and were made from August through November 1988 and 1989, and in April and May 1989. Dace
departure rates were significantly higher and feeding rates were significantly lower in foraging groups when a rainbow trout
Oncorhynchus mkiss was present (9 observations); dace arrival rates to foraging groups were not affected by presence of a trout. In
contrast, presence of other species of cyprinids (Luxilus coccogenis, Semotilus atromaculatus, Notropis leuciodus) did not significantly
affect dace arrival or departure rates to foraging groups (6 observations). We observed only infrequent aggressive interactions between
dace and trout or between dace and other cyprinids. Our results suggested that trout, but not co-occurring cyprinids, lowered the value of
a foraging site for dace, most likely by exploitative competition for drifting prey. The approach of examining foraging group dynamics in
relation to species composition provided a method of directly testing for significant interspecific interactions in the field.
109. Freeman, Mary C.; Grossman, Gary D. 1992. Group foraging by a stream minnow: shoals or aggregations? Animal
Behaviour. 44: 393-403.
The importance of social attraction in the formation of foraging groups was examined for a stream-dwelling cyprinid, the rosy side dace,
Clinostomus funduloides. Dace arrivals and departures at natural foraging sites were monitored and tested for (1) tendency of dace to
travel in groups, and (2) dependency of arrival and departure rates on group size. Dace usually entered and departed foraging sites
independently of each other. Group size usually affected neither arrival rate nor departure probability. Thus, attraction among dace
appeared weak; foraging groups most often resulted from dace aggregating in preferred foraging sites. The strongest evidence of social
attraction was during autumn, when dace departure probability often decreased with increasing group size, possibly in response to
increased threat of predation by a seasonally occurring predator. Dace also rarely avoided conspecifics, except when an aggressive
individual defended a foraging site. Otherwise, there was little evidence of exploitative competition among dace for drifting prey or of
foraging benefits in groups, because group size usually did not affect individual feeding rates. These results suggest that the benefits of
group foraging demonstrated under laboratory conditions in other studies may not always apply to field conditions.
110. Freeman, Mary C.; Grossman, Gary D. 1993. Effects of habitat availability on dispersion of a stream cyprinid. Environmental
Biology of Fishes. 37: 121-130.
We analyzed temporal changes in the dispersion of the rosy side dace, Clinostomus funduloides, (family Cyprinidae) in a headwater
stream, to assess the role of habitat availability in promoting fish aggregation. The dace foraged alone and in groups of up to about 25
individuals, and dispersion varied significantly among monthly censuses conducted from May through December. In two of three study
pools, dace aggregated during July, October, and/or December, but spread out during other months, especially during September when
dispersion did not differ significantly from random. Dispersion was not significantly correlated with the total amount of suitable habitat
available to foraging dace, but during summer, corresponded to the availability of depositional areas adjacent to rapid currents. Forager
aggregated in eddies or depositional areas during high stream discharge in July, and shifted out of depositional areas when current
velocities declined from July to September. During late autumn, however, aggregations formed independently of changes in habitat
conditions, and dace dispersion did not vary significantly among months in a third pool. The study suggests that dace dispersion cannot
be predicted from the overall availability of suitable habitat as estimated from point measurements of depth and velocity; both the
occurrence of a specific habitat feature (i.e., eddies adjacent to high velocity currents) and seasonal differences in behavior more strongly
influenced the spatial distribution of foragers.
26
111. Gibson, C.A.; Ratajczak, R.E., Jr.; Grossman, G.D. 2004. Patch based predation in a southern Appalachian stream. Oikos.
106(1): 158-166.
Streams are characterized by high degrees of patchiness that could influence the role of predators in these systems. Here we assess the
impact of predatory benthic fishes on benthic macroinvertebrate density, biomass, and community structure at the patch scale in a fourth
order stream in the southern Appalachians. We tested the role of predation in two different patch types: patches inhabited by adult
mottled sculpin (Cottus bairdi) and random patches. We placed 30 basket pairs (one open to fish predation, and one from which fish
predators were excluded) in the streambed at each patch type. We also tested for potential basket effects by setting up a basket control
area. Although there was some evidence of basket artifacts on macroinvertebrate density in sculpin patches, these artifacts were not
consistent and we do not feel that they affected our results because predators did not affect macroinvertebrate density. In random
patches, predation did not significantly affect macroinvertebrate density or biomass. Predators significantly reduced macroinvertebrate
biomass in sculpin patches but did not affect prey density. When the data-set was size-limited to exclude macroinvertebrates too large for
consumption by sculpin, macroinvertebrate biomass did not differ significantly between exclusion and open baskets. This suggests that
sculpin can reduce macroinvertebrate biomass through a combination of consumption and by predator-induced emigration of large
macroinvertebrates into areas that are protected from sculpin. In addition, invertebrate predator biomass was higher in predator exclusion
baskets in sculpin patches indicating that predation pressure Remained high in the exclusion baskets despite fish exclusion. These results
illustrate the heterogeneity of streams and the effect of small-scale differences (e.g. location of predators’ territories) on local processes.
Experiments that utilize these differences can provide insights into these stream processes.
112. Gillespie, Andrew R.; Allen, H. Lee; Vose, James M. 1994. Amount and vertical distribution of foliage of young loblolly pine
trees as affected by canopy position and silvicultural treatment. Canadian Journal of Forest Research. 24(7): 1337-1344.
The objectives of this research were to quantify the effects of tree size and silvicultural treatment on the vertical distribution of foliage of
individual trees of loblolly pine (Pinus taeda L.) and to estimate foliage quantity and distribution using easily measured tree data.
Nonlinear and linear regression models were developed to test the effects of silvicultural treatment on individual branch foliage biomass
and whole tree foliage biomass. Vertical distributions of foliage and branches were modeled using a Weibull probability density
function. Analyses indicated that individual branch foliage biomass was positively related to branch size but negatively related to
distance from the top of the tree. Fertilization with nitrogen and phosphorus, or thinning, increased the foliage biomass carried by a given
sized branch. Silvicultural treatment effects on individual branches translated into whole-tree foliage biomass with thinning and
fertilization increasing the crown size of individual trees. Though treatment affected crown size, the distribution of foliage (and
branches) remained unaffected.
113. Golladay, Stephen W. 1997. Suspended articulate organic matter concentration and export in streams. In: Webster, J.R.; Meyer,
J.L., eds. Stream organic matter budgets. Journal of the North American Benthological Society. 16: 122-131.
This chapter is part of a multi-site analysis of organic matter dynamics in streams. Terrestrial and riparian vegetation was found to play
an important role in regulating POM concentration and export, with higher values observed in forested streams and in lower gradient
streams with extensive floodplains.
114. Greenland, David. 2003. An LTER network overview and introduction to El Nino- southern oscillation (ENSO) climatic signal
and response. In: Greenland, David; Goodin, Douglass G.; Smith, Raymond C., comps. eds. Climate variability and ecosystem response
at long-term ecological research sites. New York, NY: Oxford University Press, Inc.: 102-116. Chapter 6.
This chapter gives a general introduction to ENSO and its climatic effects. However, these general patterns may mask the detailed
responses that occur at individual locations. This is one reason for presenting the principal results of previous findings related to El Nino
and LTER sites and one particular analysis focused on LTER sites. This analysis for the period 1957-1990 investigates the response
monthly mean temperature and monthly total precipitation standardized anomaly values to El Nino and La Nina events as indicated by
the Southern Oscillation Index (SOI) (Greenland 1999) The chapter then reviews some of the ENSO-related responses occurring at
LTER sites. Some of these responses are treated in more detail in other chapters in this section and this book. The goal here is to provide
an introduction to climate variability and ecosystem response at the quasi-quintennial scale. Finally, this chapter addresses some of the
framework questions of this book.
115. Grossman, G.D.; Ratajczak, R.E., Jr. 1998. Long-term patterns of microhabitat use by fish in a southern Appalachian stream
from 1983 to 1992: Effects of hydrologic period, season, and fish length. Ecology of Freshwater Fish. 7: 108-131.
We quantified microhabitat use by members of a southern Appalachian stream fish assemblage over a ten-year period that included both
floods and droughts. Our study site encompassed riffle, run, and pool habitats. Previous research indicated that species belonged to either
benthic or water-column microhabitat guilds. Most species exhibited non-random microhabitat use in all seasons, and benthic and water
column species generally were over-represented in the deeper portions of the site. In addition, water column species generally were over
represented in microhabitats with lover average velocities. The majority of seasonal shifts in microhabitat use were passive, whereas,
most shifts associated with hydrologic periods appeared to be active responses to changing environmental conditions. Most species
exhibited length-related shifts in microhabitat use, which were strongly affected by hydrologic period for four of ten species.
27
Microhabitat use patterns of assemblage members appeared to be a consequence of species-specific responses to changing environmental
conditions. The highly flexible patterns of microhabitat use exhibited by these species necessitate that decisions regarding their
management be based on data covering a range of environmental conditions.
116. Grossman, G.D.; Rincon, P.A.; Farr, M.D.; Ratajczak, R.E. Jr. 2002. A new optimal foraging model predicts habitat use by
drift-feeding stream minnows. Ecology of Freshwater Fish. 11: 2-10.
There is substantial need for models that accurately predict habitat selection by fishes for purposes ranging from the elaboration of
ecological theory to the preservation of biodiversity. We have developed a new and highly tractable optimal foraging model for driftfeeding fishes that is based on the profitably of occupying varying focal-point velocities in a stream. The basic model can be written as:
Ix=(Ex*Px) = {(D*A*V)*[1/(1 + e (b + cV))]} –SX, where: (1) IX is the net energy intake at velocity x; (2) E is prey encounter rate; (3) P is
prey capture success rate which can be modeled as 1/(1 + e (b + cV)) where b and c are fitting constants from the prey capture success
curve; (4) D is the energy content of prey (J/m3) in the drift; (5) A is the visual reactive area of the fish; (6) V is velocity (cm/s); and (7)
S is the cost of maintaining position (J/s). Given that D, A and S can be considered constant over the range of velocities occupied by
these fishes, the model reduces to e (b + cV) = 1/ (cV-1) which we solved iteratively to yield an optimal focal-point velocity for species in
each sample. We tested the model by comparing its predictions to the mean focal-point velocities (i.e. microhabitats) occupied by four
species of drift-feeding minnows in two sites in a stream in North Carolina, USA. The model successfully predicted focal-point
velocities occupied by these species (11 out of 14 cases) in three seasonal samples collected over 2 years at two sites. The unsuccessful
predictions still were within 2 cm/s of the 95% confidence intervals of mean velocities occupied by fishes, whereas, the overall mean
deviation between optimal velocities and mean fish velocities was small (range = 0.9 and 3.3 cm/s for the war paint shiner and the
Tennessee shiner, respectively). Available focal point velocities ranged from 0-76 to 0-128 cm/s depending on site and season. Our
findings represent one of the more rigorous field tests of an optimal foraging/habitat selection model for aquatic organisms because they
encompass multiple species and years, and for one species, multiple sites. Because of the case of parameterization of our model, it
should be readily testable in a range of lotic habitats. If validated in other systems, the model should provide critical habitat information
that will aid in the management of riverine systems and improve the performance of a variety of currently used management models (e.g.
instream flow incremental methodology (IFIM) and total maximum daily load calculations (TMDL)).
117. Grossman, Gary D. 1998. Notes from the blackboard. Choosing the right graduate school and getting the job you’ve always
wanted. Fisheries. 23(9): 16-17.
Graduate Mentoring Essay.
118. Grossman, Gary D.; Hill, Jennifer; Petty, J. Todd. 1995. Observations on habitat structure, population regulation, and habitat
use with respect to evolutionarily significant units: a landscape perspective for lotic systems. American Fisheries Society Symposium.
17: 381-391.
In this paper, we attempt to synthesize a variety of developments in the fields of landscape and population ecology and apply these ideas
to the physical and biological characteristics of lotic systems. First, most attempts to manage evolutionarily significant units (ESUs) are
based on the notion that the physical characteristics of lotic habitats are stable. Yet, data from three permanent 100-m reaches in the
Coweeta drainage of North Carolina indicated that these reaches possessed substantial annual variability with respect to both substratum
composition and flow rates. In addition, substratum data demonstrated that these reaches were patch environments, and that a landscapebased approach might facilitate the management of species in this system. Second, a simple landscape-driven difference equation model
of population dynamics based on biological characteristics common to many fishes indicated that the critical habitat for population
maintenance may not always be the area in which the species is most abundant. Finally, two tests for habitat selection by stream fishes
indicated that more biologically realistic models (e.g., a landscape-based model that included prey abundance) and a model that included
explicit tests for the mechanism of selection itself (e.g., energy gain) may greatly increase our ability to identify and manage habitats that
are crucial for survival of ESUs.
119. Grossman, Gary D.; McDaniel, Kathleen; Ratajczak, Robert E., Jr. 2002. Demographic characteristics of female mottled
sculpin, Cottus bairdi, in the Coweeta Creek drainage, North Carolina. Environmental Biology of Fishes: 63: 299-308.
We quantified: (1) growth rate, (2) length-mass relationships, (3) size- and age-specific fecundity, (4) egg size-frequencies,
and (5) size- and age-specific egg diameter relationships for reproductively active female C. bairdi from one of the southern-most extant
populations of this species (Coweeta Creek drainage, North Carolina). Gravid females were collected during February and March in
1993–1995, and 1998. Cottus bairdi reached an age of 7 +and 79 mm standard length. The youngest and smallest gravid female collected
was a 41 mm 1 +individual. Mature 1 +females were not uncommon and we collected 21 during our study. All females older than age 2
were mature. Mean fecundity for C. bairdi at Coweeta was 71 eggs (range 9–166 eggs). We found significant positive relationships
between fecundity and female length, weight and age. Female length and weight also significantly affected mean egg diameter, although
the relationship was not linear. Neither female size or age significantly affected mean maximum egg diameters. Female C. bairdi from
the Coweeta Creek drainage possess a unique suite of reproductive characteristics that may represent adaptations to the local selective
regime or ecophenotypic variation.
28
120. Grossman, Gary D.; Ratajczak, Robert E., Jr.; Crawford, Maurice K. 1995. Do rock bass (Ambloplites rupestris) induce
microhabitat shifts in mottled sculpin (Cottus bairdi)? Copeia. 2: 343-353.
In Coweeta Creek, North Carolina, mottled sculpin (Cottus bairdi) co-occurred seasonally with a potential predator, rock bass
(Ambloplites rupestris). We conducted experiments to determine whether rock bass affected microhabitat use by sculpin in an artificial
stream. The general behavior and microhabitat use of both species in the artificial stream resembled those observed in Coweeta Creek.
When all microhabitat observations were pooled, there was little evidence of predator-induced shifts by sculpin. However, at night in
trials without predators, sculpin generally occurred farther from shelter, over greater amounts of gravel and lower quantities of erosional
substrata. When we added predators, however, this response was obviated. Nonetheless, the lack of strong responses by sculpin to rock
bass, coupled with their co-occurrence only during seasons of low metabolic activity, lead us to suspect that rock bass do not produce
strong shifts in microhabitat use by most sculpin in the Coweeta drainage.
121. Grossman, Gary D.; Ratajczak, Robert E., Jr.; Crawford, Maurice; Freeman, Mary C. 1998. Assemblage of organization
in stream fishes: effects of environmental variation and interspecific interactions. Ecological Monographs. 68(3): 395-420.
We assessed the relative importance of environmental variation, interspecific competition for space, and predator abundance on
assemblage structure and microhabitat use in a stream fish assemblage inhabiting Coweeta Creek, North Carolina, USA. Our study
encompassed a 10-yr time span (1983-1992) and included some of the highest and lowest flows in the last 58 years. We collected 16
seasonal samples, which included data on: (1) habitat availability (total and microhabitat) and microhabitat diversity, (2) assemblage
structure, and (3) microhabitat use and overlap. We classified habitat availability data on the basis of year, season, and hydrologic
period. Hydrologic period (i.e., pre-drought [PR], drought [D], and post-drought [PO]) represented the temporal location of a sample
with respect to a four-year drought that occurred during the study. Hydrologic period explained a greater amount of variance in habitat
availability data than either season or year. Total habitat availability was significantly greater during PO than in PR or D, although
microhabitat diversity did not differ among either seasons or hydrologic periods. There were significantly fewer high-flow events (i.e., ³
2.1 m3/s) during D than in either PR or PO periods. We observed a total of 16 species during our investigation, and the total number of
species was significantly higher in D than in PR samples. Correlation analyses between the number of species present (total and
abundant species) and environmental data yielded limited results, although the total number of species was inversely correlated with total
habitat availability. A cluster analysis grouped assemblage structure samples by hydrologic period rather than season or year, supporting
the contention that variation in annual flow had a strong impact on this assemblage. The drought had little effect on the numerical
abundance of benthic species in this assemblage; however, a majority of water-column species increased in abundance. The increased
abundances of water-column species may have been related to the decrease in high-flow events observed during the drought. Such highflow events are known to cause mortality in stream fishes. Microhabitat use data showed that species belonged to one of three
microhabitat guilds: benthic, lower water column, and mid water column. In general, species within the same guild did not exhibit
statistically distinguishable patterns of microhabitat use, and most significant differences occurred between members of different guilds.
However, lower water-column guild species frequently were not separable from all members of either benthic or mid-water-column
species. Variations in the abundance of potential competitors or predators did not produce strong shifts in microhabitat use by
assemblage members. Predators were present in the site in only 9 of 16 seasonal samples and never were abundant. In conclusion, our
results demonstrate that variability in both mean and peak flows had a much stronger effect on the structure and use of spatial resources
within this assemblage then either interspecific competition for space or predation. Consequently, we suspect that the patterns in both
assemblage structure and resource use displayed by fishes in Coweeta Creek arose from the interaction between environmental variation
and species-specific evolutionary constraints on behavior, morphology, and physiology.
122. Grubaugh, J.W.; Wallace, J.B.; Houston, E.S. 1996. Longitudinal changes of macroinvertebrate communities along an
Appalachian stream continuum. Canadian Journal of Fisheries and Aquatic Sciences. 53: 896-909.
Richness and mean annual abundance and biomass of benthic taxa were measured in prevalent habitats along a first- through seventhorder stream continuum in the southern Appalachian Mountains (United States). Richness was greatest in midorder reaches, and benthic
densities were highest in cobble habitats, followed by bedrock, pebble-gravel, and depositional areas. Abundance-based estimates of
functional feeding-group composition were dominated by collector-gatherers and changed little with habitat. In contrast, biomass-based
estimates differed greatly among habitats: collector-filterers generally dominated cobble and bedrock areas; collector-gatherers, in
pebble-gravel; and shredders and collector-gathers, in depositional habitats. When functional-group biomass estimates were weighted for
relative habitat continuum concept (RCC), although localized changes in stream geomorphology also influenced community structure.
Habitat-weighted abundance estimates did not produce similar trends. Because RCC predictions are based on benthic biomass, caution
and qualification must be exercised when using abundance data to test RCC predictions.
123. Hairston, Nelson G., Sr. 1993. On the validity of the name teyahalee as applied to a member of the Plethodon glutinosus
complex (Caudata: Plethodontidae): a new name. Brimleyana. 18: 65-69.
The name Plethodon teyahalee (Hairston) cannot be applied to the member of the P. glutinosus complex as designated by Highton
(1983). Biochemical data show that the population from which the type of teyahelee was taken consists of hybrids between local
populations representing the P. jordani and P. glutinosus complexes, and thus cannot be applied to a member of either of those two
29
species under Article 23(h) of the International Code of Zoological Nomenclature (1985). A new name, Plethodon oconaluftee, is
proposed, and a new type is designated.
124. Hairston, Nelson G., Sr.; Wiley, R. Haven. 1993. No decline in salamander (Amphibia: Caudata) populations: A twenty-year
study in the southern Appalachians. Brimleyana 18: 59-64.
Identical observations, conducted 1-4 times per year for 15-20 years at two locations in the southern Appalachians, have yielded
quantitative data on populations of six species of salamanders. Although the numbers have fluctuated for various reasons, there has been
no trend in the numbers of any of the species. The "world-wide decline of amphibian populations" has not occurred in the two localities
studied.
125. Hairston, Nelson G., Sr.; Wiley, R. Haven; Smith, Charles K. 1992. The dynamics of two hybrid zones in Appalachian
salamanders of the genus Plethodon. Evolution. 46(4): 930-938.
Two zones of intergradation between populations of Plethodon have been studied for 18 and 20 years, respectively. The data consist of
systematic scores of colors, made at least twice annually. Near Heintooga Overlook in the Balsam Mountains (Great Smoky Mountains
National Park), the salamanders' cheeks are gray. Proceeding north toward Smokies, there is increasing frequency and intensity of red
color at two, four, and six miles. There has been no change in the scores at any location. The width of the zone and our failure to detect
any change can be explained by assuming neutrality of the character and random diffusion during the probable time since contact
between the two intergrading forms, which most likely took place after the Hypsithermal Interval, 8,000 - 5,000 BP. At Coweeta
Hydrologic Laboratory in the Nantahala Mountains, Plethodon jordani, and P., glutinosus hybridize at intermediate elevations. The
lateral white spots of glutinosus decrease and the red on the legs of jordani increases with elevation from 685 m to 1,052 m. At the
higher elevation, the proportion of animals scored as "pure" jordani declined significantly from 1974 to 1990, an indication that the
hybrid zone is spreading upward. The rate of spread is too great to be explained by random diffusion, so selection for glutinosus
characters is the best explanation. The rate of spread of the hybrid zone indicates that hybridization in other organisms.
126. Hall, Robert O., Jr. 1995. Use of stable carbon addition to trace bacterial carbon through a stream food web. Journal of the
North American Benthological Society. 14(2): 269-277.
The use of bacterial carbon by stream invertebrates was assessed by dripping 13C as sodium acetate into a headwater spring at Coweeta
Hydrologic Laboratory for three weeks during August 1992. The addition raised the d 13C value of dissolved organic carbon from
approximately -26% to approximately 100%. Coarse particulate organic matter, fine particulate organic matter (FPOM), and 14 taxa of
animals were analyzed by mass spectrometer before and after the 13C addition. Pre-addition sample d13C ranged from -36% to -22%,
post-addition samples ranged from -35% to 129%. Predators contained less 13C label than collectors, shredders, and scrapers. Shredders
were not uniformly labeled, suggesting low use of bacterial carbon. Stenonema (Heptageniidae), a biofilm scraper, was the most highly
labeled taxon (up to 128%), even though biofilm d 13C was -16%. Chironmomids and copepods were clearly labeled and had a higher
d13C than the FPOM, suggesting preferential assimilation of bacterial carbon relative to FPOM. Although adults and larvae of
Optioservus (Elmidae) are believed to be scrapers, the adults were more labeled than the larvae, indicating greater dependence on
bacterial carbon. Gut analyses of Optioservus corroborated the stable isotope results: adult guts contained mostly detritus whereas larval
guts contained a high proportion of diatoms. This technique is useful for determining the relative differences in bactivory by an
assemblage of stream animals.
127. Hall, Robert O. Jr.; Meyer, Judy L. 1998. The trophic significance of bacteria in a detritus-based stream food web. Ecology.
79(6): 1995-2012.
We compared relative use of streamwater dissolved organic carbon (DOC) by bacteria and the trophic significance of bacteria to
invertebrates in tow headwater streams at Coweeta Hydrologic Laboratory in North Carolina: a stream with all leaf litter inputs excluded
for 1 yr, and a reference stream. Leaf litter standing crop in the treatment stream was <1% that of the reference stream, and fine benthic
organic matter (FBOM) was 50% lower than the reference. We used a whole-stream tracer addition of 13C-1 sodium acetate for 3 wk to
label bacteria and hence their consumers during both July and December. Bacterial d 13C was measured by collecting respired bacterial
carbon. We estimated the contribution of bacterial carbon to consumers using a mixing model for invertebrates and bacteria. The acetate
label declined exponentially downstream with a 10-m uptake length in each stream and season. FBOM and biofilm were the only detrital
samples to show a strong label; both were more labeled in the litter-excluded stream. Bacteria in the litter-excluded stream had 7-10
times more label than those in the reference stream during both seasons, showing their higher relative use of streamwater DOC. The
percentage of invertebrate carbon derived from bacteria was >20% for many taxa. This was significantly related to the percentage of
amorphous detritus in invertebrate guts, suggesting that bacterial carbon supporting higher trophic levels was associated with amorphous
detrital particles. Predatory invertebrates were labeled, showing that bacterial carbon was important for higher trophic levels. Some
invertebrates were more highly labeled than the bacteria. Stenonema in the treatment stream contained eight times more label than
measured bacteria. This suggests that they were using an unmeasured bacterial source such as bacteria in exposed epilithic biofilms,
which had higher d13C than all other detrital components. Invertebrates in the treatment stream did not appear to use more bacterial
carbon than in the reference stream despite a lower standing crop of detritus. Tallaperla, a shredding stonefly, derived 20-40% of its
carbon from bacteria in both streams, even though it was more labeled in the treatment stream. Our estimates of the percentage of
invertebrate carbon derived from bacteria were higher than those found in laboratory-based studies. To investigate reasons for this
30
difference, we examined the possibility that bacterial carbon was principally found in exopolymers, as our labeling method would have
labeled exopolymers. We found 6 g/m2 of colloidal carbohydrates in the reference stream, which was five times greater than bacterial
biomass; thus, the high use of bacterial carbon by invertebrates may be a consequence of the availability of these polymers.
128. Hall, Robert O. Jr.; Peredney, Christopher L.; Meyer, Judy L. 1996. The effect of invertebrate consumption on bacterial
transport in a mountain stream. Limnology and Oceanography. 41(6): 1180-1187.
Although laboratory studies have shown that filter-feeding invertebrates consume bacteria from stream water, no study has measured
bacterial consumption in the field or determined system-level removal rates of sestonic bacteria. To examine bacterial removal rates and
consumption by invertebrates, we released fluorescently labeled bacteria (FLB) in to a second-order stream at Coweeta Hydrologic
Laboratory, North Carolina. We performed two 1-h releases during summer over bedrock habitat that supports many filter feeders. We
calculated uptake length and counted FLB in the guts of seven insect taxa. Uptake length was 78 and 83 m for the two releases, which
corresponded to uptake rates of 4.03 and 3.69 X 10 7 cells m-2 min-1. Simulium, a filter-feeding blackfly larva, ingested FLB at a rate of
1.4 X 104 cells mg-1 min-1, 10 times the rate of other taxa. Diplectrona and Parapsyche, hydropsychid caddisfly filter feeders, had
ingestion rates between Simulium and other taxa. Epeorus, a scraping mayfly, and Tallaperla, a shredding stonefly, also ingested FLB,
presumably from cells that adhered to the substrate. Invertebrate ingestion per square meter of stream bottom was 7% of total stream
uptake, with Simulium responsible for 91% of the total invertebrate ingestion. Adhesion of FLB to the substrate from the water column
seemed to be more important than invertebrate consumption in this stream, and one taxon, Simulium, was responsible for most
invertebrate consumption of bacteria.
129. Hall, Robert O., Jr.; Peterson, Bruce J.; Meyer, Judy L. 1998. Testing a nitrogen-cycling model of a forest stream by using a
nitrogen-15 tracer addition. Ecosystems. 1: 283-298.
Cycling of nitrogen (N) is commonly studied in aquatic ecosystems; however, most studies examine only parts of the N cycle, such as
budgets, N uptake lengths, or oxidative transformations. To integrate conceptually and experimentally several aspects of the N cycle in a
stream; we combined a N-cycling model and a tracer addition of nitrogen 15 (15N) to Hugh White Creek, a second-order forested
mountain stream in North Carolina (USA). We calibrated a steady-state box model for N cycling in a 5-m stream segments that included
dissolved, detrital, and biotic compartments. This model was parameterized based on prior studies and used to predict the expected
distribution of tracer 15N in all compartments through both time and distance downstream of the addition site. We tested the model
results with a 23-day continuous addition of 15N-NH4+ to the stream. Deviations of field data from model predictions suggested areas in
which we lacked understanding of the N cycle. Downstream distribution of 15N in epilithon and moss matched model predictions,
indicating that our prior estimations of N uptake rates were correct. Leaves and fine detritus contained less label than predicted by the
model, yet their consumers had both higher d15N than predicted and higher d15N than the detritus itself, suggesting selective assimilation
of microbial N from ingested detritus. Splitting fine benthic organic N (FBON) into a microbial and recalcitrant pool gave better
predictions of FBON and seston d15N values relative to field data, yet overestimated invertebrate consumer d 15N possibly because our
estimates of the fraction of invertebrate N derived from microbes were too high. We predicted that much of the labeled N would move
downstream via FBON suspension and transport. We found that most of the 15N remained near the addition site 33 days after the
addition was stopped, suggesting that the stream is highly retentive of particulate N.
130. Hall, Robert O., Jr.; Wallace, J. Bruce; Eggert, Susan L. 2000. Organic matter flow in stream food webs with reduced detrital
resource base. Ecology. 81(12): 3445-3463.
Food webs based on flows of organic matter were developed for two small streams to examine food web response to a large reduction in
detrital inputs. At the study site, Coweeta Hydrologic Laboratory in the southern Appalachians, leaf litter inputs and associated microbial
assemblages are the main energy source for food webs in headwater streams. We eliminated leaf litter inputs to one stream using a net
placed over the first 180 m of stream from its origin. Food webs based on flow of organic matter were developed for a referenced stream
and the litter-excluded stream for two months, July and December of year 1 of the litter exclusion, to examine effects of leaf litter
exclusion on the trophic base of the food web, size distribution of flows, predator-prey interactions, and trophic structure. Flows (mg
AFDM·m-2·d-1; AFDM = ash-free dry mass) were estimated using gut content analyses for detritus and prey items, coupled with
secondary production estimates. We used a whole-stream 13C tracer method to estimate assimilation of bacteria by invertebrates. The
food webs encompassed most (84-91%) of invertebrate secondary production, but <30% of the estimated total links. The primary sources
of organic matter for the food web in the reference stream were leaf tissue, bacterial carbon, and animal prey, with ~25-30% of total
secondary production derived from each. In-stream primary production led to <1% of invertebrate secondary production. A higher
fraction of food web production in the litter-excluded stream was derived from wood. Magnitudes of detrital flows were lower in the
litter-excluded stream, and some taxa were missing compared to the reference stream. The fraction of predator ingestion approached
100% of total secondary production of both streams, but this predation was distributed diffusely among several taxa. Flows to predators
were fewer and smaller in the litter-excluded stream, yet these flows had higher per-biomass consumption coefficients, suggesting
stronger interactions among the remaining common taxa. These food webs enabled us to examine interactions among taxa in the streams;
hence, we found responses of the stream ecosystem ecosystem to litter-exclusion that we would not have considered had we only
measured changes in invertebrate population sizes or system-level changes in organic matter flow.
31
131. Hannah, Peter R. 1993. Composition and development of two Appalachian hardwood stands in North Carolina. The Journal of
the Elisha Mitchell Scientific Society. 109(2): 87-98.
Many events have shaped Appalachian forest structure and composition since the arrival of European settlers in the 1700s. Initially the
forest was cleared for farming and adjacent woodlands burned annually for grazing. Mountain farms were ultimately abandoned and the
invaded by forest. Extensive harvesting of remaining original and second growth forests began before 1900. Chestnut blight during the
early 1900s caused further major changes. Harvesting and other land uses continue to shape the forest landscape today. Forests still
dominate the more rugged sections of the region, and a few old and little-disturbed stands remain. Stand tally and stem analysis in
Appalachian hardwood forests studied species composition, age structure, and height growth of existing trees. In a mature stand at Bent
Creek the oldest trees, northern red oak and white oak, predate the 1870 land clearing. However, most trees became established between
1902 and 1915 after agricultural abandonment. In the early 1930s, chestnut mortality opened the canopy for red maple, black birch,
sourwood, black gum, and flowering dogwood. Present mortality is primarily black locust and black oak in the main canopy and
flowering dogwood in the understory. Density of tree seedlings less than 2 m tall is low. The oldest trees are over 30 m tall but some
established 60 years later are of equal height. At Coweeta, most trees became established after a heavy cut about 1920. Other trees
entered the stand following the chestnut blight. Occasional large residual red oaks are dying, creating large gaps for a third age class.
While considerable oak is in the main canopy, there is little oak regeneration. Composition may ultimately be dominated by sugar maple,
white ash, yellow birch, and yellow buckeye. As these stands mature, gaps are likely to occur as a result of mortality of single trees or
groups of trees. Stands will become more diverse in their age structure.
132. Hansen, Randi, A. 1999. Red oak litter promotes a microarthropod functional group that accelerates its decomposition. Plant and
Soil. 209: 37-45.
The contribution of microarthropod activity to litter decomposition varies widely but can be substantial. Oribatid mites are the most
diverse and abundant of the microarthropod groups in forest litter. This experiment was designed to examine the effect of litter type and
complexity on the diversity and species composition of oribatid mites, and to test whether alterations in species composition due to litter
type affected litter decomposition. In an array of plots on a mixed-hardwood site in the mountains of North Carolina, I exposed
microarthropod assemblages to a range of litter types: yellow birch, sugar maple, red oak and two mixed litters. Over several years, the
litter types selected oribatid mite assemblage of different species composition. By comparing the decomposition of consecutive cohorts
of litter, it was possible to detect differences in decomposition accompanying the shifts in the assemblage. A comparison of the mass loss
rates between the two litter cohorts over eighteen months reveals similar trajectories for four litter types. In the oak litter, however, the
second cohort disappeared significantly faster than the first. In both years, the litters came from the same trees and were nearly identical
in initial carbon and nitrogen contents. Since the response was specific to oak litter, it is unlikely that differences in environmental
factors are responsible for the faster mass loss of oak. A significant increase of endophagous oribatid mites, those that burrow into plant
material, in the second cohort of oak may account for its accelerated decomposition. The woody petioles and thick leaf-planes of oak
leaves provide microhabitats for burrowing mites. Endophage activity can accelerate the litter decomposition both through direct
comminution of leaf material and by facilitating microbial growth. Because of their low population growth rates, oribatid populations
that are reduced by disturbance are slow to recover and by disrupting these non-resilient populations, disturbance may have long-term
repercussions for decomposition.
133. Hansen, R.A. 2000. Diversity in the decomposing landscape. In: Coleman, D.C.; Hendrix, P.F., eds. In: Invertebrates as
webmasters in ecosystem: New York, NY. CABI Publishing: 203-219.
At practically any terrestrial site, the vast majority of the animal species are invertebrate members of the decomposer community. In
temperate forests, these animals, primarily arthropods and nematodes, are concentrated in the decomposing organic layers that make up
the top few centimeters of the soil. As thin and fragile as this layer is, it is the zone through which most of the productivity of the system,
as leaves, roots, wood and animal debris, passes and is transformed. Through their activity as microbial grazers and saprophages, the
decomposed fauna is the gate-keeper to the flow of material through the system.
In ecosystem-level models of nutrient cycling, this zone and its inhabitants are most commonly represented by several compartments
through which nutrients flow, entering as a large pulse input at litterfall and leaving through plant uptake, leaching, denitrification and
respiration. But the mechanisms that regulated decomposer interaction webs, their structure and biotic diversity, are nested on a finer
scale of resolution, one that discerns structure within the litter profile and the dynamics of its annual fluctuations. A mechanistic
understanding of the organization of soil assemblages and their mediation of processes will require study on this scale. In this chapter, I
will focus on the most diverse of the litter-dwelling mesofaunal groups, the non-astigmatic oribatid mites, and how the morphology and
dynamics of the litter profile determine their diversity, species composition and their functional impact. As a case study, I will discuss an
experiment that compared the oribatid assemblage in profiles developed form monotypic litter, the typical medium for studying litter
dynamics and a common consequence of human activities, with those in profiles developed from natural, mixed litter.
134. Hansen, Randi, A. 2000. Effects of habitat complexity and composition on a diverse litter microarthropod assemblage. Ecology.
81(4): 1120-1132.
Oribatid mites (Acari: Oribatida) are the most diverse arthropod group in forest litter and soil, and they make significant contributions to
decomposition as microbial grazers and saprophages. As is true for all the hyperdiverse soil taxa, the determinants of their diversity and
32
species composition are virtually unexplored. The experiment tests whether heterogeneity of the litter habitat is a determinant of their
local diversity, and whether litter composition is a determinant of their species composition. At a single site of temperate deciduous
forest at the Coweeta Hydrological Laboratory in the mountains of North Carolina, USA, natural litterfall was excluded from a series of
42 1-m² plots and, for three consecutive years, replaced with treatment litters that varied in their composition and complexity. Plots of
pure yellow birch (Betula alleghaniensis), sugar maple (Acer saccharum), and red oak (Quercus rubra) litter comprised the monotypic
or simple litter treatments. Two complex litters included a mixture of these three litter species and a mixture of seven litter species with
pieces of small woody debris.
Monotypic litters developed profiles of reduced thickness that contained lower numbers of invading roots and less humic and arthropod
fecal material. Over 3 yr, oribatid abundance and richness declined substantially and to a similar degree in all simple litter treatments,
though the dominant species, Oppiella nova, was unaffected by litter simplification. Similarity of species composition increased
markedly among replicates within each litter treatment for two sectors of the assemblage: the large, litter-dwelling species and the
endophagous and wood-associated species. Species composition among small litter-dwellers was unresponsive to litter type. Several
characteristics of monotypic-litter habitats potentially contributed to the erosion of the oribatid assemblage. Loss of structure in
monotypic litter likely led to reduced and less hospitable physical living space. It appeared to reduce recruitment of roots and retention of
humic and fecal material in the litter layer. Each monotypic litter contained only a subset of the structural microhabitats that serve as
refugia for eggs and juveniles. Finally, the synchronized decomposition of uniform substrates could have led to a “boom-bust” economy
in microbial resources that was unfavorable to oribatid mites and their conservative life histories.
135. Hansen, Randi A.; Coleman David C. 1998. Litter complexity and composition are determinants of the diversity and species
composition of oribatid mites (Acari: Oribatida) in litterbags. Applied Soil Ecology. 9: 17-23.
To investigate the relationship between litter complexity and composition and the diversity and composition of the oribatid mite fauna
inhabiting it, an experiment was carried out at a single forested site in the mountains of North Carolina, USA. Natural litterfall was
excluded from a series of 1 m2 plots and replaced with treatment litters that varied in composition and complexity. Plots of pure birch,
maple, and oak litter comprised the simple litter treatments. Two complex litters were made of a mixture of these three litter species and
a mixture of seven litter species. Treatment litters were applied to the plots in the autumn of 1993 and again in 1994. The oribatid mites
extracted from litterbags of the treatment litters from both years are reported on here. Mixed litters had a significantly greater variety of
microhabitats, as defined by substrate type and fungal growth form, than did the simple litters. Likewise, the oribatid mite species
richness in litterbags of mixed liter was significantly higher than that in the simple litters. The fauna within replicates of each litter-type
were more similar to each other than to those of other treatments. A third of the mite species tested showed a differential response among
the simple litter-types. These results indicate a link between heterogeneity and diversity of mites active in a particular horizon of litter
and some influence of litter-type upon species composition. Such patterns in habitat use by adult mites are strong, though not conclusive
evidence of the ultimate role of heterogeneity in maintaining the diversity of oribatid mites.
136. Harding, J.S.; Benfield, E.F.; Bolstad, P.V.; Helfman, G.S.; Jones, E.B.D. III. 1998. Stream biodiversity: The ghost of land
use past. In: Proceedings of the national academy of sciences of the United States of America. 95: 14843-14847.
The influence of past land use on the present-day diversity of stream invertebrates and fish was investigated by comparing watersheds
with different land-use history. Whole watershed land use in the 1950s was the best predictor of present-day diversity, whereas riparian
land use and watershed land use in the 1990s were comparatively poor indicators. Our findings indicate that past land-use activity,
particularly agriculture may result in long-term modifications to and reductions in aquatic diversity, regardless of reforestation of
riparian zones. Preservation of habitat fragments may not be sufficient to maintain natural diversity in streams, and maintenance of such
biodiversity may require conservation of much or all of the watershed.
137. Hardt, Richard A.; Swank, Wayne T. 1997. A comparison of structural and compositional characteristics of southern
Appalachian young second growth, maturing second growth, and old-growth stands. Natural Areas Journal. 17(1): 42-52.
Forest stand structural and compositional characteristics were studied in two stands each of Southern Appalachian old growth, maturing
second growth (previously selectively logged), and young second growth (previously clearcut) to determine differences among these
stands. Mature second growth and young second growth represent common stand conditions in this region. Tree species diversity was
highest in maturing second growth, intermediate in old growth, and lowest in young second-growth stands. Old-growth stands had an
overstory tree composition of a mix of shade-intolerant and intermediate species; maturing second-growth overstories were dominated
by intermediate species; young second-growth overstories were dominated by shade-intolerant species. Densities of large live trees, trees
with cavities, and snags were highest in old-growth stands and lowest in young second-growth stands. Log accumulations were highest
in one young second-growth stand and lowest in another young second-growth stand that had been clearcut twice. Log accumulations in
old-growth stands were higher than in maturing second-growth stands. Maturing second-growth stands were more similar in structural
characteristics to the old-growth stands than to the young second-growth stands. Stand history appears to have highly influenced many
structural and compositional characteristics. Although the sample size was small, the old-growth stands have several characteristics that
developed as a result of their undisturbed history; these characteristics should be considered during planning for future old growth on
Southern Appalachian national forests.
33
138. Harper, Craig A.; Guynn, David C., Jr. 1998. A terrestrial vacuum sampler for macroinvertebrates. Wildlife Society Bulletin.
26(2): 302-306.
Macroinvertebrate abundance and biomass is an important consideration when managing upland game birds. Although several
techniques have been employed sampling macroinvertebrate communities, the advantages of sampling with a vacuum sampler are
discussed. Instructions are given on modifying a blower/vac into a vacuum sampler for macroinvertebrates. Cost efficiency, ease of use
and increased mobility make this vacuum sampler more attractive than the D-vac sampler. Potential value as a sampling tool for other
ecological data, such as salamander density and mast abundance, make this sampler a useful tool for a variety of sampling situations.
139. Harper, Craig A.; Guynn, David C., Jr. 1999. Factors affecting salamander density and distribution within four forest types in
the southern Appalachian Mountains. Forest Ecology and Management. 114: 245-252.
We used a terrestrial vacuum to sample known area plots in order to obtain density estimates of salamanders and their primary prey,
invertebrates of the forest floor. We sampled leaf litter and measured various vegetative and topographic parameters within four forest
types (oak-pine, oak-hickory, mixed mesophytic and northern hardwoods) and three age classes (0-12, 13-39, and ³ 40-years) over two
field seasons within the Wine Spring Creek Ecosystem Management area in western North Carolina. We found salamanders’ preferred
moist microsites across all forest types with the highest salamander densities occurring on sites with a northern and/or eastern exposure
and within northern hardwood forests. Salamander densities were lowest on 0-12-year plots, yet were equal on 13-39 and ³ 40-year plots,
suggesting a much quicker recovery from the impact of clearcutting than reported by previous researchers. Overall invertebrate densities
did not influence salamander density or distribution although, plots in which salamanders were captured harbored significantly higher
numbers of snails than plots in which salamanders were not captured. We discuss the importance of calcium to salamanders and snails as
a possible source thereof.
140. Hayden, Bruce P.; Hayden, Nils R. 2003. Decadal and century-long changes in storminess at long-term ecological research
sites. In: Greenland, David; Goodin, Douglass G.; Smith, Raymond C., comps. eds. Climate variability and ecosystem response at longterm ecological research sites. New York, NY: Oxford University Press, Inc.: 262-285. Chapter 14.
This paper examines the history of storminess for 19 Long – Term Ecological Research (LTER) sites in the continental United States
based on more than a century of data on storms and their storm tracks. Analyses showed that storm frequencies have changed over much
of the continental U.S. since 1885 and very large changes in storm frequency are found at most LTER sites. However, when averaged
over the entire U.S., no net change in storminess was detected. El Nino/ La Nina variations in storminess were not detected either
nationally or regionally.
141. Hedman, Craig W.; Van Lear, David H. 1994. Large woody debris loading patterns in southern Appalachian streams. In:
Riparian ecosystems in the humid U.S.: functions, values and management; 1993 March 15-18; Atlanta, GA. Washington, DC: National
Association of Conservation Districts: 240-243.
Riparian zone vegetation is a source of large woody debris (LWD), which affects the ecology, and morphology of streams. This study
has identified baseline LWD loadings in small Southern Appalachian streams. Twelve riparian/stream systems approximately 500 m in
length were sampled in 15 m units. LWD was defined as any portion of a tree, i.e., bole, limb, root wad, or whole tree, that was >10 cm
diameter and >1.5 m in length. All LWD was scaled within an area defined by a stream's bankfull channel width plus a 1 m lateral
buffer. LWD loadings per sample unit were characterized as low (2.8 m3), medium (2.8-5.7 m3), or high (>5.7 m3).
142. Hedman, Craig W.; Van Lear, David H. 1995. Vegetative structure and composition of southern Appalachian riparian forest.
Bulletin of the Torrey Botanical Club. 122(2): 134-144.
Vegetative characteristics of twelve Southern Appalachian riparian forests were sampled as part of a larger study, which examined
functional attributes of riparian zones. Riparian forests were representative of the mixed mesophytic forest, eastern hemlock forest, and
transitions between these types. Early- and mid-successional stages were generally dominated by an overstory of pioneering shadeintolerant species and had an even-aged structure. The diameter distribution of these relatively young stands of mixed species was
typically inverse J-shaped. Late-successional and old growth stages were dominated by an overstory of pioneering shade-intolerant or
moderately tolerant overstory species and were uneven-aged. Diameter distribution in these older stands approximated a rotated sigmoid
curve. Rhododendron (Rhododendron maximum L.) was the dominant understory species and controlled understory and midstory
composition. Characterization of riparian forests in different stages of succession will help understanding of vegetative processes and
forms the basis of subsequent ecological studies of riparian functional dynamics.
143. Hedman, Craig W.; Van Lear, David H.; Swank, Wayne T. 1996. In-stream large woody debris loading and riparian forest
seral stage associations in the southern Appalachian mountains. Canadian Journal of Forest Resources. 26: 1218-1227.
Large woody debris (LWD) is an important ecological component of mountain streams. However, the relation of LWD loading and
riparian forest composition is poorly understood in the southern Appalachians. In this study, 500-m reaches of 11 riparian forest-stream
systems representing a 300-year sere were inventoried and measured to obtain quantitative estimates and descriptions of in-stream LWD.
34
Loading volumes ranged from 7.1 to 31.2 m3/100 m of stream, or between 3.6 and 13.2 kg/m2. LWD loadings were highly variable
during midseral stages of plant community succession, primarily because of the wide range in loading of American chestnut. Loadings
increased linearly in late-successional through old-growth systems over a 165-year interval. Eastern hemlock and American chestnut
were the most dominant carry-over LWD species in midsuccessional stream systems. Loading of eastern hemlock LWD increased from
midsuccessional through old-growth stages as the species became dominant in the riparian forest. Without carry-over debris, LWD
loadings would be extremely low in midsuccessional stream systems. American chestnut was a major component of LWD in
midsuccessional stream systems, despite the fact that it has been unavailable for recruitment for decades.
144. Hendrick, R.L. 2001. Forest types and classification. In: Evans, J.; Morris, L., eds. The Forests Handbook, Vol. I. London:
Blackwell Science. 23-64. Chapter 2.
Closed canopy forests and savannahs occupy a tremendous amount of land, approximately 3540 million ha (Perr 1994) or abut 26% of
the earth’s terrestrial surface (FAO 1997). Tropical forests comprise approximately 35% of the total, temperate forest 17%, boreal forest
16%, and the remainder is savannah and open woodlands. Among countries and continents, about 520 million ha of forest are in Africa
(15.1%), 465 million ha in Asia and Oceania (16.4%), 146 million ha in Europe (4.2%), 950 million ha in South America, Central
America and the Caribbean (27.5%), 457 million ha in North America (13.2%) and 816 million ha in the countries of the former USSR
(23.6%). There is tremendous floristic diversity in these forests, with more than 10,000 know species of trees and shrubs, and tens of
thousands of species of non-woody vascular and non-vascular understory plants and epiphytes. The tropical forests are the most diverse,
with over 2500 species of trees in both the Malay Peninsula and South America for example.
145. Heneghan, L; Coleman, D.C.; Zou, X; Crossley, D.A.; Haines, B.L. 1999. Soil microarthropod contributions to
decomposition dynamics: Tropical-temperate comparisons of a single substrate. Ecology. 80(6): 1873-1882.
This study examined the effect of soil microarthropods on the decomposition of a single substrate (Quercus prinus L.) at two humid
tropical forests (La Selva, Costa Rica [LAS] and Luquillo Experimental Forest, Puerto Rico [LUQ]} and one temperate forest (Coweeta
Hydrologic Station, North Carolina, USA [CWT]). In this litterbag experiment, naphthalene was applied to reduce the microarthropod
population density from half of three replicate plots established at each site. This enabled us to quantify the mass loss contributed by the
fauna (MLCF) at each site and permitted an analysis of the influence of site-specific differences in the composition of the
microarthropod assemblages on decomposition rates. We hypothesized that microarthropod regulation of the microbial populations
involved in leaf litter decomposition would be stronger in humid tropical forests which experience conditions of low climatic variability.
In these conditions, there can be an enhanced degree of biotic interactions between microarthropods and their microbial food sources.
The elevated extent of these interactions should be expressed as a greater influence of microarthropods at the tropical sites and could
result in a site-specific effect of faunal assemblages on decomposition. Decomposition of the oak litter proceeded faster in Puerto Rico
and Costa Rica forests than in a temperate forest in North Carolina, USA. Microarthropods had little effect on decomposition in the
temperate forest, whereas their influence was pronounced at tropical sites. Mass loss of litter from plots with reduced microarthropod
populations was similar at the tropical sites. When plots with intact faunal communities were compared, differences in the tropical sites
were apparent, suggesting that there was a site-specific faunal contribution to decomposition at these sites. Orbatid mites constituted a
dominant component (41-64%) at each of the sites. Species richness of oribatids and Fisher's alpha diversity were similar in each of the
three sites. The Shannon index revealed a lower diversity at LUQ. Abundance of microarthropods was lowest at LAS. Species
accumulation curves for each site, though similar in form, were distinctive, as were diversity accumulation patterns in samples of
increasing size. There was a positive relationship between species richness and the contribution of the fauna to litter mass loss within
each site. Thus, species diversity of decomposer fauna may have important ecosystem consequences, particularly in warm moist tropical
forests.
146. Heneghan, L; Coleman, D.C.; Zou, X.; Crossley, D.A., Jr.; Haines, B.L. 1998. Soil microarthropod community structure and
litter decomposition dynamics: a study of tropical and temperate sites. Applied Soil Ecology. 9: 33-38.
The influence of climate, substrate quality, and microarthropods on decomposition was studied by comparing the mass loss of litter at
three forested sites: two tropical and one temperate. At each site, litterbags containing a dominant local litter were placed in the field in
replicated plots. Half the bags were treated with naphthalene to reduce microarthropod abundance. The pattern of mass loss was
markedly seasonal at the temperate site. The amount of mass remaining after 250 days were strongly related to the initial %N of the three
litter types (r2=0.997). The faunated litterbags lost more mass at all sites and for all litters studied than the litterbags with reduced
microarthropod populations. The effect was minimal at the temperate site where the fauna tended to increase the decomposition rate only
towards the end of the year. In contrast, the effect of the fauna at the tropical sites was marked within months of the start of the
experiment. Species richness of microarthropods in samples of 300 cm2 of leaf litter was similar at the three sites. However, diversity
was greatest at the tropical sites.
147. Heneghan, Liam; Coleman, David C.; Crossley, D.A., Jr.; Xiaoming, Zou. 1999. Nitrogen dynamics in decomposing
chestnut oak (Quercus prinus L.) in mesic temperate and tropical forest. Applied Soil Ecology. 13: 169-175.
This study examined nitrogen dynamics in decomposing Quercus prinus L. litter, confined in litterbags, in two tropical forests (La Selva
Biological Station, Costa Rica, and Luquillo Experimental Forest. Puerto Rico) and on temperate forest site (Coweeta Hydrologic
35
Laboratory, NC). Using regressions of %N in the decomposing litter against litter mass remaining. We demonstrated similar
concentrations of N at all sites when the amount of litter lost was 50%. By using naphthalene, an arthropod repellent, we examined the
effect of microarthropod on the N fluxes in the litterbags. Microarthropod had little effect on the %N remaining. At La Selva, the
presence of fauna resulted in a marginally significant increase in litter nitrogen concentrations (p<0.06). At both tropical sites, there was
a significant net immobilization of N followed by N mineralization after four months. Although there was a net immobilization of N at
Coweeta, this lasted for a longer period and the litterbags had not begun to mineralize N after 10 months. We suggest that the rapid
accumulation of N in decomposing litter at the tropical sites during the first few months after leaf fall can result in the retention of
mobile nitrogen ions in soils. The subsequent mineralization in later decomposition stages, can make N available to trees during leaf
flush.
148. Heneghan, Liam; Salmore, Alissa; Crossley, D.A., Jr. 2004. Recovery of decomposition and soil microarthropod communities
in an Appalachian watershed two decades after a clearcut. Forest Ecology and Management. 189: 353-362.
We examined decomposition rates of three substrates (Quercus prinus L., Acer rubrum L., and Cornus florida L.) in a watershed 21
years after it had been clearcut, and compared them to an adjacent control watershed. Previous investigations at these sites had shown
that microarthropod populations, important components of the decomposer community, were considerably less dense in the clearcut
watershed and that decomposition rates were reduced. Twenty-one years after clearcut decomposition rates in the clearcut watershed had
reconverged with the control, and in the case of one substrate (C. florida) now exceeded the control. Microarthropods maintained denser
populations in the clearcut watershed, and oribatid assemblages, the most abundant taxonomic group, were more diverse in that
watershed. A contrast of the decomposition of the substrates 8 and 21 years after cable-logging revealed that decomposition was slower
in the control watershed in the more recent observations, though this may reflect lower precipitation that year. These results seem to
confirm that microarthropod recovery may be indicative of a restored decomposer community functioning, and that this may be
reflective of reconverged abiotic conditions at the site.
149. Hicks, Norman, G.; Menzel, Michael A.; Laerm, Joshua. 1998. Bias in the determination of temporal activity patterns of
syntopic peromyscus in the southern Appalachians. Journal of Mammalogy. 79(3): 1016-1020.
We compared inferred activity patterns of two syntopic rodents, Peromyscus leucopus, and P. maniculatus, in western North Carolina.
Activity patterns were derived from capture-frequency data obtained from Sherman live-traps equipped with digital timers following
different trapping protocols. We tested the hypothesis that no differences would be observed in frequency distribution of captures from
trapping grids monitored only in the morning (control) compared with grids where captured animals were released during the night and
in the morning (treatment). Distributions of frequencies of captures on control and treatment grids were significantly different. On
control grids, capture frequencies (based on 3-h intervals) of both species were higher in the first 3 h after sunset and decreased
thereafter throughout the night, but frequencies of captures of both species were uniform throughout the night on treatment grids.
Photographic records from automated cameras suggested increasing levels of activity throughout the night. Activity patterns derived
from camera data were different from those derived from the control and treatment grids. Inferences regarding activity patterns are
sensitive to method and trapping-protocol bias.
150. Hicks, Norman, G.; Pearson, Scott M. 2003. Salamander diversity and abundance in forests with alternative land use histories
in the Southern Blue Ridge Mountains. Forest Ecology and Management. 177: 117-130.
The diversity and abundance of terrestrial salamanders were compared at 12 forest stands having three different land use histories: (a)
success ional forest established on abandoned farmland; (b) second/third growth forests that had experienced timber harvest; (c) stands
having few to no alterations due to land use. Populations were estimated using pitfall trapping conducted during July 1997 1997-June
1998 in the Southern Blue Ridge Province of the Southern Appalachian Mountains. Salamander diversity did not differ among land use
categories; however, abundances were greater in the older, least-altered stands. Abundances were positively correlated with late
successional qualities of forest, such as increased domination by mesophytic tree species and increased availability of wood debris.
However, we did not find large differences between stands that had experienced previous agricultural uses and those that had not been
farmed, only logged. At our sites, enough time had passed since agricultural use that any differences between agricultural and forestry
uses had diminished. These results show both the sensitivity of salamanders to past habitat alterations and the resiliency of these
populations in their ability to recover in these ecosystems given sufficient time.
151. HilleRisLambers, Janneke; Clark, James S.; Beckage, Brian. 2002. Density-dependent mortality and the latitudinal gradient
in species diversity. Nature. 417: 732-735.
Ecologists have long postulated that density-dependent mortality maintains high tree diversity in the tropics1-6. If species experience
greater mortality when abundant, then more rare species can persist 1, 2, 7-9. Agents of density-dependent mortality (such as host-specific
predators, and pathogens) may be more prevalent or have stronger effects in tropical forests, because they are not limited by climatic
factors 1-5. If so, decreasing density-dependent mortality with increasing latitude could partially explain the observed latitudinal gradient
in tree diversity4-6. This hypothesis has never been tested with latitudinal data. Here we show that several temperate tree species
experience density-dependent mortality between seed dispersal and seedling establishment. The proportion of species affected is
equivalent to that in tropical forests6, 10-16, failing to support the hypothesis that this mechanism is more prevalent at tropical latitudes.
36
We further show that density-dependent mortality is misinterpreted in previous studies. Our results and evidence from other studies
suggest that density-dependent mortality is important in many forests. Thus, unless the strength of density-dependent mortality varies
with latitude, this mechanism is not likely to explain the high diversity of tropical forests.
152. Hoover, Coeli M.; Crossley, D.A. Jr. 1995. Leaf litter decomposition and microarthropod abundance along an altitudinal
gradient. In: Collins, H.P.; Robertson, G.P.; Klug, M.J., eds. The significance and regulation of soil biodiversity. Netherlands: Kluwer
Academic Publishers. 287-297.
Mass loss rates of three types of leaf litter were measured along an altitudinal gradient at the Coweeta Hydrologic Laboratory, Macon
County, North Carolina. Litterbags containing air-dried litter from Quercus prinus L., Liriodendron tulipifera L., and Rhododendron
maximum L. were placed in five plots along the gradient and sampled monthly. Microarthropods were extracted and sorted, and litter
was weighed to determine mass loss. Decomposition rate constants were calculated for all litter types at each sample point along the
gradient. Microarthropod abundance was also examined for all litter types across the gradient; the possible relationships of climatic
factors to decomposition rates and microarthropod abundance were explored.
153. Hu, S.; Coleman, D.C.; Carroll, C.R.; Hendrix, P.F.; Beare, M.H. 1997. Labile soil carbon pools in subtropical forest and
agricultural ecosystems as influenced by management practices and vegetation types. Agriculture, Ecosystems and Environment. 65: 6978.
Carbon storage in agricultural and forest soils has attracted attention recently due to its potential as a substantial carbon sink. Labile soil
C pools are especially important because they are more vulnerable to climatic change and disturbance and play vital roles in nutrient
cycling. Southern Appalachian forest soils and those from conventional tillage (CT), no-tillage (NT) and fescue sods at three sites in the
Georgia piedmont were analyzed for total C, total N, carbohydrates, and microbial biomass C. The sizes of soil labile C pools and their
contributions to the total soil C pool differed significantly among ecosystems. The highest carbohydrate contents and microbial biomass
C was found in forest soils, but agricultural soils had a significantly higher proportion of the soil organic matter present as carbohydrates
and as microbial biomass. This difference probably reflects the quality of soil organic matter. Soil microbial biomass C was more
sensitive to changes in management regimes than soil carbohydrates. Management practices significantly affected organic C,
carbohydrate contents, microbial biomass C and organic C turnover rates in agricultural soils, whereas differences in the quality of
organic input due to different vegetation types substantially influenced soil labile C pools in forest soils. High mannose-to-xylose ratios
in highly sandy agricultural soils indicate that plant-derived materials are rapidly metabolized by microorganisms and that organic C
protection in sandy soils is largely dependent on reducing microbial access through effective residue management such as surface
placement.
154. Hubbard, Robert M.; Vose, James M.; Clinton, Barton D.; Elliott, Katherine J.; Knoepp, Jennifer D. 2004. Stand
restoration burning in oak-pine forests in the southern Appalachians: effects on aboveground biomass and carbon and nitrogen cycling.
Understory prescribed burning is being suggested as a viable management tool for restoring degraded oak–pine forest communities in
the southern Appalachians yet information is lacking on how this will affect ecosystem processes. Our objectives in this study were to
evaluate the watershed scale effects of understory burning on total aboveground biomass, and the carbon and nitrogen pools in coarse
woody debris (CWD), forest floor and soils. We also evaluated the effects of burning on three key biogeochemical fluxes; litterfall, soil
CO2 flux and soil net nitrogen mineralization. We found burning significantly reduced understory biomass as well as the carbon and
nitrogen pools in CWD, small wood and litter. There was no significant loss of carbon and nitrogen from the fermentation, humus and
soil layer probably as the result of low fire intensity. Burning resulted in a total net loss of 55 kg ha-1 nitrogen from the wood and litter
layers, which should be easily replaced by future atmospheric deposition. We found a small reduction in soil CO 2 flux immediately
following the burn but litterfall and net nitrogen mineralization were not significantly different from controls throughout the growing
season following the burn. Overall, the effects of burning on the ecosystem processes we measured were small, suggesting that
prescribed burning may be an effective management tool for restoring oak–pine ecosystems in the southern Appalachians.
155. Hunter, Mark D. 2001. Insect population dynamics meets ecosystem ecology: effects of herbivory on soil nutrient dynamics.
Agricultural and Forest Entomology. 3: 77-84.
In reality, the idea that insect herbivores may regulate nutrient availability and primary production has no fundamental link with theories
of mutualism or plant fitness. Plant productivity is measured in different units (carbon per m2 per year) and at a different level of
organization (the community) than is fitness (proportional representation in the next generation measured at the level of individual
plants). Theories of herbivore-mediated changes in nutrient cycling need not be found guilty by association with controversial views of
herbivores as mutualists. Given the recent interest in the role of species in ecosystems (Jones & Lawton, 1995) and publications by
Schowalter (2000) and Belovsky & Slade (2000), it is worth re-examining potential effects of insect herbivores on ecosystem function.
The discussion that follows is limited to the effects of foliar-feeding herbivores on soil nutrient dynamics and subsequent productivity.
Effects of wood-boring insects on nutrient dynamics are well documented (e.g. Dale et al., 1990) and, although root feeding insects can
influence nutrients in soils (Maron & Connors, 1996; Maron & Jefferies, 1999; Hunter 2001), the effects of below-ground fauna on
nutrient dynamics are a whole other can of worms, so to speak. In addition, although the focus of this article will be insect folivores, I
37
beg your indulgence if a few four-legged and eight-legged herbivores make brief appearances to illustrate an occasional ecological
principle.
156. Hunter, Mark D.; Adl, Sina; Pringle, Catherine M.; Coleman, David C. 2003. Relative effects of macroinvertebrates and
habit on the chemistry of litter during decomposition. Pedobiologia. 47: 101-115.
During the decomposition of terrestrial leaf litter, the concentrations of lignin, tannin, cellulose, hemicellulose, nitrogen, and carbon are
known to change. These chemical changes have been associated with subsequent colonization and activity of decomposer flora and
fauna. Here, we report that chemical changes in litter during the first twelve months of decomposition are affected by macroinvertebrate
activity. Moreover, chemical changes are associated most closely with the activities of invertebrate predators. Using litter bags that either
excluded (fine mesh) or allowed access by (coarse mesh) macroinvertebrates, we followed the concentrations of lignin, tannin, cellulose,
hemicellulose, nitrogen, and carbon in the litter of Liriodendron tulipifera, Quercus prinusi and Rhododendron maximum in a North
Carolina forest ecosystem. We also compared chemical changes in these litters at a riparian site and an upland site within the forest. The
exclusion of macroinvertebrates decreased concentrations of nitrogen and total phenolics in the litter of L. tulipifera, increased
concentrations of cellulose and condensed tannin in Q. prinus litter, and increased the concentrations of condensed tannin in R.
maximum litter in the riparian zone. Although fine mesh bags excluded most macroinvertebrates, the greatest effects of exclusion were
upon ants and spiders, not macroinvertebrate decomposers. Our data therefore suggest that predator-mediated changes in the decomposer
communities were responsible for observed shifts in litter chemistry. Predator effects on litter chemistry were likely mediated by their
interactions with fungivorous and bacterivorous fauna. For example, Collembola populations were 34% higher in litter bags from which
macroinvertebrates were excluded. Litter chemistries also differed between the riparian and upland sites. For both L. tulipifra and R.
maximum, effects of habitat were limited to higher concentrations of condensed tannin in the upland site. In contrast, habitat effects
upon the litter chemistry of Q. prinus were pervasive. Specifically, Q. prinus litter in the upland habitat exhibited slower increases in
lignin, more stable concentrations of cellulose, slower increases in hemicellulose, higher concentrations of total phenolics, and higher
concentrations of hydrolysable tannins than did litter in the riparian habitat. Overall, our data provide the first evidence that predators in
the litter of deciduous forests can influence the chemistry of litter during the decomposition process.
157. Hunter, Mark D.; Forkner, Rebecca E.1999. Hurricane damage influences foliar polyphenolics and subsequent herbivory on
surviving trees. Ecology. 80(8): 2676-2682.
Hurricane damage results in tree mortality and variation in both light and nutrient availability for the individuals that remain. In turn,
resource availability influences the interactions between plants and insect herbivores. We report effects of Hurricane Opal on the
phenolic chemistry and levels of defoliation on surviving trees at the Coweeta Hydrologic Laboratory in North Carolina. We measured
foliar astringency, hydrolysable tannins, and condensed tannins in the foliage of red maple and red oak saplings in hurricane-damaged an
undamaged site. We estimated inorganic nitrogen and phosphorus availability in the soil, and the accumulated leaf area removed by
insect herbivores. The foliar astringency of both red maple and read oak was higher in sites damaged by the hurricane. Later in the
growing season, condensed tannin levels were significantly higher in the foliage of red oak in damaged sites. There were no consistent
differences in ammonium, nitrate, or phosphate availability between damaged and undamaged sites. Despite higher foliar astringency of
trees in sites damaged by Hurricane Opal, levels of defoliation by insect herbivores were higher in damaged than in control sites on both
tree species. Apparent increases in putative defensive compounds following hurricane damage did not protect trees from herbivory.
158. Hunter, Mark D.; Linnen, Catherine R.; Reynolds, Barbara C. 2003. Effects of endemic densities of canopy herbivores on
nutrient dynamics along a gradient in elevation in the southern Appalachians. Pedobiologia. 47: 231-244.
In southern Appalachian forests, outbreaks of insect herbivores have been shown repeatedly to increase the availability of nutrients in
soil and the export of nitrate in forest streams. The mechanisms underlying herbivore-induced changes in nutrient dynamics include
inputs of insect frass (feces) and modification of precipitation as it passes through the forest canopy (throughfall). Here, we consider the
effects of endemic (non-outbreak) populations of insect herbivores on soil processes in the southern Appalachians. We measured inputs
of frass and throughfall at three elevations at the Coweeta Hydrological Laboratory, North Carolina. We also measured soil nutrient
availability and soil respiration. Inputs of total frass, frass nitrogen and frass carbon exhibited early-and late-season peaks, with those
peaks occurring earlier at low elevation where leaf flush begins first. The C: N ration generally increased over time at all elevations,
presumably reflecting seasonal declines in foliar nitrogen. Nitrate in throughfall generally increased over time, whereas throughfall
phosphate declined and throughfall ammonium remained relatively constant. Relationships among frass deposition and throughfall
nutrients varied with elevation. At low elevation, frass nitrogen was strongly correlated with throughfall nitrate, but this relationship was
absent at mid and high elevation. The relationships between frass deposition and throughfall ammonium were inconsistent among
elevations. The availabilities of nitrate and ammonium in soil were both related to frass deposition. For example, frass deposition in May
explained about 62% of the variance in soil nitrate availability. Soil respiration exhibited summer maxima at all elevations and was
related primarily to soil temperature. There was also a weak positive relationship between the C: N ratio of frass and soil respiration.
Overall, we suggest that endemic densities of canopy herbivores can influence forest soil processes, but that the relationships exhibit
pronounce spatial and temporal variability.
159. Hursh, Charles R. 1959. Forest influences in worldwide application. In: Essays on forests and hydrology in honor of Professor
Burger's 70th.birthday. Mitteilungen der Schweizerishchen Anstalt fur das forstilche Versuchswesen. Bd .35, Heft 1:31-36.
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** No Abstract **
160. Huryn, Alexander D.; Wallace, J. Bruce. 2000. Life history and production of stream insects. Annual Reviews Entomology.
45: 83-110.
Studies of the production of stream insects are now numerous, and general factors controlling the secondary production of stream
communities are becoming evident. In this review, we focus on how life-history attributes influence the production dynamics of stream
insects and other macroinvertebrates. Annual production of macroinvertebrates communities in streams worldwide ranges from
approximately 10° to 103 g dry mass m -2. High levels are reported for communities dominated by filter feeders in temperate streams.
Filter feeding enables the accrual and support of high biomass, which drives the very highest production. Frequently disturbed
communities in warm-temperate streams are also highly productive. Biomass accrual by macroinvertebrates is limited in these streams,
and production is driven by rapid growth rates rather than high biomass. The lowest production, reported for macroinvertebrate
communities of cool-temperate and arctic streams, is due to the constraints of low seasonal temperatures and nutrient or food limitation.
Geographical bias, paucity of community-wide studies, and limited knowledge of the effects of biotic interactions limit current
understanding of mechanisms controlling stream productivity.
161. Hutchens, J.J., Jr.; Benfield, E.F. 2000. Effects of forest defoliation by the gypsy moth on detritus processing in southern
Appalachian streams. The American Midland Naturalist. 143: 397-404.
We investigated whether changes in chestnut oak (Quercus prinus L.) leaf quality caused by gypsy moth (Lymantria dispar L.)
defoliation affected leaf breakdown rates in southern Appalachian streams of differing disturbance history. Breakdown rats of second
flush leaves produced after defoliation were compared to those of natural spring-flush leaves shed in autumn. Second-flush leaves broke
down significantly faster than spring-flush leaves in three of the six streams tested. Initial fiber content and the ratio of fiber to protein
were significantly higher in spring-flush leaves than in second-flush leaves, showing that initial differences in internal leaf constituents
could explain the faster breakdown rates of second flush leaves. Using changes in leaf toughness through time as a measure of microbial
conditioning, we found that the faster-decaying second-flush leaves also softened at a faster rate than the spring-flush leaves. In addition,
both types of leaves incubated in three streams draining a recovering 14-y-old clear-cut catchment broke down significantly faster than
leaves incubated in three streams draining a reference catchment. We attributed this increase in leaf breakdown to significantly higher
abundance and density of leaf-shredding insects and greater microbial conditioning in leaf packs in the streams of the recovering clearcut catchment. Overall, our results show that insect defoliation accelerates detritus processing in southern Appalachian streams and that
this acceleration may be especially important in previously disturbed streams in which leaves are already processed faster.
162. Hutchens, John J., Jr.; Benfield, Ernest F.; Webster, Jackson R. 1997. Diet and growth of a leaf-shredding caddisfly in
southern Appalachian streams of contrasting disturbance history. Hydrobiologia. 346: 193-201.
Diet and growth of leaf-shredding caddisfly larvae, Pycnopsyche spp., were examined in streams draining a reference catchment and a
16-year-old clear-cut (disturbed) catchment at Coweeta Hydrologic Laboratory in southwestern North Carolina, USA. The objective was
to explain why shredder production is higher in the disturbed streams despite the larvae having less food available. We predicted larvae
would grow faster on fast decaying leaf material representative of the disturbed streams. Larvae consumed mostly leaf detritus in three
streams draining each catchment over three seasons, which showed larvae did not consume higher quality foods in disturbed streams.
When fed 2-month-old conditioned black birch and white oak leaves in the laboratory, larvae grew significantly faster on the birch
leaves. However, when larvae were fed the same leaf types after 3-months conditioning, larvae grew significantly faster on oak leaves. A
field growth experiment conducted for 42 d using mixed-species leaf diets representative of each catchment and initially conditioned for
2 months found that Pycnopsyche grew significantly better on the diet representative of the reference catchment. The reference diet
contained more oak leaves, which apparently became a more acceptable food as the experiment proceeded. High shredder production in
the disturbed streams could not be explained by high Pycnopsyche growth rates on fast-decaying leaves. Instead, larvae grew better on
leaves that were apparently conditioned optimally regardless of conditioning rate.
163. Hutchens, John J., Jr.; Chung, Keun; Wallace, J. Bruce. 1998. Temporal variability of stream macroinvertebrate abundance
and biomass following pesticide disturbance. Journal of the North American Benthological Society. 17(4): 518-534.
We determined the extent of macroinvertebrate recovery in a former pesticide-treated stream (FTS) relative to a reference stream (RS)
by examining macroinvertebrates colonizing red maple (Acer rubrum L.) litterbags between 5 to 10 y following pesticide treatment.
Mean abundance and biomass, variability in abundance and biomass (using the coefficient of variation [CV]), and assemblage structure
were compared both within and among years to assess recovery. The 5 y of study included 3 drought years followed by 2 wet years.
Mean total abundance and biomass of macroinvertebrates, and that of most functional feeding groups (FFG) did not significantly differ
between streams during this study, nor did within-year variability of these means, indicating macroinvertebrates in FTS had recovered
relative to RS. Some exceptions to the above patterns resulted from the dynamics of a single taxon in each group. Macroinvertebrate
assemblage structure in litterbags was similar between streams throughout the study as shown by their similar ordination scores; hence,
assemblage structure had also recovered. In each stream, mean annual abundance and biomass of total macroinvertebrates and of each
FFG, aside from shredder abundance, differed significantly among years. However, assemblage structure was generally similar among
39
years. Among-year CVs were usually lower than within-year CVs because macroinvertebrate abundance and biomass fluctuated more
during a year than it did from year to year, and different processes apparently contributed to the variation observed at these 2 time scales.
For example, juvenile development time influenced within-year CVs, indicating that life-history characteristics affected temporal
variability of macroinvertebrate abundance and biomass. Examination of both the means and their variances was useful for determining
the extent of recovery and how macroinvertebrates responded to natural environmental variability. The detailed analysis of temporal
dynamics at different time scales afforded by the CV supported our contention that FTS had recovered from the pesticide application
relative to RS.
164. Hutchens, John, J., Jr.; Wallace, J. Bruce. 2002. Ecosystem linkages between southern Appalachian headwater streams and
their banks: Leaf litter breakdown and invertebrate assemblages. Ecosystems. 5: 80-91.
We examined red maple (Acer rubrum L.) leaf litter breakdown in streams and riparian zones at two sites in the southern Appalachian
Mountains to understand how differences in abiotic and biotic factors influence leaf breakdown rates. Litterbags were placed in three
riparian habitats differing in litter layer moisture: stream > bank > upland. Invertebrates colonizing litterbags at one site were also
examined to determine how variations in community and functional structure affect breakdown rates. Leaves broke down fastest in
streams and slowest in upland habitats, whereas bank habitats were intermediate and characterized by high variability. Faster leaf
breakdown rates in streams appeared to be a function of greater moisture availability, a more stable thermal regime, and a higher
biomass of leaf-shredding invertebrates, especially the stonefly Tallaperia. In addition, patterns of leaf breakdown and invertebrate
community structure provided evidence for a stronger than expected ecological connection between the stream and the bank. Overall,
detritus processing within this narrow riparian ecosystem varied considerably depending on the availability of moisture. Results from
this study show that stream channel-flood-plain interactions in riparian ecosystems of steep forested mountains are analogous to ones in
larger downstream or low-gradient systems. Riparian zones throughout a river network display a remarkable heterogeneity in their ability
to process organic matter, which is ultimately driven by changes in hydrological conditions.
165. Ives, Anthony R.; Turner, Monica G.; Pearson, Scott M. 1998. Local explanations of landscape patterns: Can analytical
approaches approximate simulation models of spatial processes? Ecosystems. 1: 35-51.
Research over the last 100 years has demonstrated the importance of space for ecological processes. Given this importance, it may seem
natural to start investigations into broad-scale ecological processes with a comprehensive, broad-scale spatial map. Here we argue that it
may sometimes be possible to answer important questions about spatial processes using crude spatial information obtained when a
comprehensive map is not available. To present our argument, we first develop a simple simulation model for a perennial plant
reproducing and dying on a landscape with different arrangements of suitable and unsuitable sites. We them develop a simple, analytical
approximation to predict the fraction of suitable sites that are occupied by the simulated plants. The analytical approximation
summarizes the spatial map by using a single parameter that gives the probability that a site adjacent to a suitable site is suitable.
Comparing the predictions of both approaches highlights three points: (a) the role of the spatial environment in ecological processes may
play out at the local scale. Therefore, studying the local-scale processes may provide insights into landscape patterns. (b) The predictions
from the analytical approximation fail noticeably when suitable sites are rare and are distributed randomly (rather than clumped) on the
map. In these situations, patches of interconnected suitable sites are very small, and populations within small patches may go extinct via
demographic stochasticity. This illustrates how analytical approximations can be used to identify cases when local-scale spatial
processes are not sufficient to understand the ecological consequences of space. (c) For many natural systems, constructing the
appropriate environmental map needed to study ecological processes is difficult or impossible. However, summary characteristics such
as those employed by the analytical approximation may be estimated directly in nature. Therefore, even in the absence of an explicitly
spatial broad-scale map, it may be possible to study spatial processes by understanding, which local-scale characteristics of space are
important.
166. Jakeman, A.J.; Hornberger, G.M. 1993. How much complexity is warranted in a rainfall-runoff model? Water Resources
Research. 29(8): 2637-2649.
Development of mathematical models relating the precipitation incident upon a catchment to the streamflow emanating from the
catchment has been a major focus of surface water hydrology for decades. Generally, values for parameters in such models must be
selected so that runoff calculated from the model “matches” recorded runoff from some historical period. Despite the fact that the
physics governing the path of a drop of water through a catchment to the stream involves complex relationships, evidence indicates that
the information content in a rainfall-runoff record is sufficient to support models of only very limited complexity. This begs the question
of what limits the observed data place on the allowable complexity of rainfall-runoff models. Time series techniques are applied for
estimating transfer functions to determine how many parameters are appropriate to describe the relationship between precipitation and
streamflow in the case where data on only precipitation, air temperature, and streamflow are available. Statistics from an “information
matrix” provide the clues necessary for determining allowable model complexity. Time series models are developed for seven
catchments with widely varying physical characteristics in different temperate climatic regimes to demonstrate the method. It is found
that after modulating the measured rainfall using a nonlinear loss function; the rainfall-runoff response of all catchments is well
represented using a linear model. Also, for all catchments a two-component linear model with four parameters is the model of choice.
The Two compontes can be interpreted as defining a “quick flow” and “slow flow” response of the given catchment. The method
therefore provides a statistically rigorous way to separate hydrographs and parameterize their response behavior. The ability to construct
40
reliable transfer function models for describing the rainfall-runoff process offers a new approach to investigate empirically the controls
of physical catchment descriptors, land use change, climate change, etc., on the dynamic response of catchments through the extensive
analysis of historical data sets.
167. Johnson, D.W.; Knoepp, J.D.; Swank, W.T.; Shan, J.; Morris, L.A.; Van Lear, D.H.; Kapeluck, P.R. 2002. Effects of forest
management on soil carbon: results of some long-term resampling studies. Environmental Pollution.116: S201-S208.
The effects of harvest intensity (sawlog, SAW; whole tree, WITH; and complete tree, CTH) on biomass and soil C were studied in four
forested sites in the southeastern US (mixed deciduous forests at Oak Ridge, TN and Coweeta, NC; Pinus taeda at Clemson, SC; and P.
eliottii at Bradford, FL). In general, harvesting had no lasting effects on soil C. However, intensive temporal sampling at the NC and SC
sites revealed short-term changes in soil C during the first few years after harvesting, and large, long-term increases in soil C were noted
at the TN site in all treatments. Thus, changes in soil C were found even though lasting effects of harvest treatment were not. There were
substantial differences in growth and biomass C responses to harvest treatments among sites. At the TN site, there were no differences in
biomass at 15 years after harvest. At the SC site, greater biomass was found in the SAW than in the WITH treatment 16 years after
harvest, and this effect is attributed to be due to both the N left on site in foliar residues and to the enhancement of soil physical and
chemical properties by residues. At the FL site, greater biomass was found in the CTH than in the WITH treatment 15 years after
harvest, and this effect is attributed to be due to differences in understory competition. Biomass data were not reported for NC. The
effects of harvest treatment on ecosystem C are expected to magnify over time at the SC and FL sites as live biomass increases, whereas
the current differences in ecosystem C at the TN site (which are due to the presence of undecomposed residues) are expected to lessen
with time.
168. Johnson, D.W.; Susfalk, R.B.; Brewer, P.F.; Swank, W.T. 1999. Simulated effects of reduced sulfur, nitrogen, and base cation
deposition on soils and solutions in southern Appalachian forests. Journal of Environmental Quality. 28: 1336-1346.
Effects of reduced deposition of N, S, and CB on nutrient pools; fluxes, soil, and soil solution chemistry were simulated for two
Appalachian forest ecosystems using the nutrient cycling model. In the extremely acidic, N- and S-saturated red spruce [Picea rubens
(Sarg.)] forest (Nolan Divide), reducing CB deposition by 50% reduced CB leaching by ~40% during the 24-yr simulation period. This
was due solely to the effects of CB deposition on the soil exchanger rather than effects on soil solution. Reducing S an N by 50% caused
immediate reductions in total anion and cation leaching at Nolan Divide, but the effects on soil solution CB diminished and CB leaching
was reduced by only 17% over the simulation period. Reducing S and N deposition had a greater effect on soil solution aluminum (AI)
and molar Ca/A1 ratio than reducing base cation deposition at Nolan Divide. In the moderately acidic, N- and S-accumulating mixed
deciduous forest at Coweeta, reduced CB deposition by 50% caused a very slight (<4%) reduction in CB leaching as a result of slightly
reduced base saturation and increased soil sulfate adsorption. The effects on reducing S and N deposition by 50% on CB Leaching (16%
over the simulation period) were greater than those of reduced CB deposition. The system continued to accumulate both S and N even at
reduced deposition at Coweeta, although growth and vegetation uptake were slightly reduced (-5%) because of increased N deficiency.
Base saturation remained well above the Al buffering range at all times at Coweeta and Al was an unimportant component of soil
solutions in all scenarios.
169. Johnson, D.W.; Swank, W.T.; Vose, J.M. 1993. Simulated effects of atmospheric sulfur deposition on nutrient cycling in a
mixed deciduous forest. Biogeochemistry. 23: 169-196.
The effects of three S deposition scenarios (50 % reduction, no change, and 100 % increase) on the cycles of N, P, S, K, Ca, and Mg in a
mixed deciduous forest at Coweeta were simulated using the Nutrient Cycling model (NuCM). Both the simulations and the measured
20-year trends in streamwater SO2/4- concentration suggest that the ecosystem is slowly becoming S saturated. Streamwater data suggest
S saturation is occurring at a slower rate than indicated by the simulations, perhaps because of underestimation of organic S retention in
the model. Both the simulations and field data indicate substantial declines in exchangeable bases in A and BA soil horizons, primarily
due to vegetation uptake. Varying S deposition had very little effect upon simulated vegetation growth, nutrient uptake, or N cycling.
Varying S deposition strongly affected simulated Ca2+, Mg, 2+ K+, and P leaching but caused little change in soil exchangeable pools of
Ca2, K+, or P because soil exchangeable pools were large relative to fluxes. The scenario for 100 % increased S deposition caused
increasing peaks in simulated Al concentrations in A horizons after 25 years as a result of large seasonal pulses of SO 2/4- and lowered
base saturation. Simulated soil solution Al3+ concentrations remained well below toxicity thresholds for selected tree species at the site.
170. Johnson, Dale W.; Susfalk, Richard B.; Dahlgren, Randy A. 1997. Nutrient fluxes in forests of the eastern Sierra Nevada
Mountains, United States of America. Global Biogeochemical Cycles. 11(4): 673-681.
Soil nutrient contents and fluxes in semiarid lodgepole and jeffrey pine stands of the eastern Sierra Nevada mountains are described and
compared to those in the Integrated Forest Study sites. These Sierran forests, like others in the southwestern United States, have very low
N, S, and H+ fluxes compared to more humid forests. Base cation fluxes in these Sierran forests are high relative to more humid forests,
however, reflecting the high base status of the soils, inputs from nearby desert systems, and high rates of soil weathering. Soil C and N
contents in these Sierran forests are low compared to those in more humid forest, probably because of lower primary productivity and
more frequent fire. Soil extractable P pools in these Sierran forests vary by 2 orders of magnitude and are strongly influenced by parent
material. As in most snow-dominated systems, pulses of NO3- are released from the melting snow pack each spring in the Sierran forests.
41
Nitrogen released from melting snow pack is retained in the soil in most cases, but there are substantial springtime pulses of NO3- in
stream waters during dry years. Budget calculations indicated that N losses during fire and N gains associated with postfire N-fixing
vegetation are an order of magnitude greater than N inputs and outputs via solution phase.
171. Johnson, Dale W.; Swank, Wayne T.; Vose, James M. 1995. Effects of liming on soils and streamwaters in a deciduous forest:
comparison of field results and simulations. Journal of Environmental Quality. 24: 1105-1117.
Soil and stream chemical responses to liming in a deciduous forest watershed at Coweeta, NC, are compared with simulation results
using the Nutrient Cycling Model (NuCM). Field comparisons of limed and unlimed soils after 23 yr indicated substantial net retention
of applied Ca and Mg in upper soil horizons, even in black locust sites where NO 3 leaching was elevated. We hypothesized that NuCM
simulations would also show that (i) retention of most applied Ca and Mg in the upper horizons and (ii) increased Ca and Mg retention
with increased cation exchange capacity (CEC) and exchangeable H. Both hypotheses were supported by simulation results for Ca, but
not for Mg. Most applied Mg in the simulations was retained in the BC horizon, where the largest pool of exchangeable Mg was initially
located. Increasing CEC and exchangeable H did result in increased retention of applied Ca and Mg in surface horizons. However,
increasing CEC caused lower Mg retention in the BC horizon, which offset the surface horizon increases and resulted in lower total
retention of applied Mg. Simulated BC horizon soil solution concentrations mimicked the general patterns in streamwater NO 3, Mg, Na,
Cl, SO4, and K between 1971 (12 yr after liming) and 1979. NuCM simulations did not, nor was it possible to simulate the observed
effects of an insect outbreak on streamwater NO3.
172. Johnson, Dale; Geisinger, Donn; Walker, Roger; Newman, John; Vose, James; Elliot [Elliott], Katherine; Ball, Timothy.
1994. Soil pCO2, soil respiration, and root activity in CO2-fumigated and nitrogen-fertilized ponderosa pine. Plant and Soil. 165: 129138.
The purpose of this paper is to describe the effects of CO2 and N treatments on soil pCO2, calculated CO2 efflux, root biomass and soil
carbon in open-top chambers planted with Pinus ponderosa seedlings. Based upon the literature, it was hypothesized that both evaluated
CO2 and N would cause increased root biomass, which would in turn cause increases in both total soil CO2 efflux and microbial
respiration. This hypothesis was only supported in part: both CO2 and N treatments caused significant increases in root biomass, soil
pCO2, and calculated CO2 efflux, but there were no differences in soil microbial respiration measured in the laboratory. Both correlative
and quantitative comparisons of CO2 efflux rates indicated that microbial respiration contributes little to total soil CO 2 efflux in the field.
Measurements of soil pCO2 and calculated CO2 efflux provided inexpensive, non-invasive, and relatively sensitive indices of
belowground response to CO2 and N treatments.
173. Johnson, Dale W.; Susfalk, Richard B.; Swank, Wayne T. 1998. Simulated effects of atmospheric deposition and species
change on nutrient cycling in loblolly pine and mixed deciduous forests. In: Mickler, Robert A.; Fox, Susan, eds. The productivity and
sustainability of southern forest ecosystems in a changing environment. Ecological Studies. vol. 128. New York, NY. Springer-Verlag:
503-524. Chapter 27.
The interesting effect of fire atmospheric deposition scenarios and forest species change on soil nutrient changes are examined through
simulations with the nutrient-cycling model (NUCM). Deposition changes included: 1) no change, 2) 200% N deposition, 3) 50% of S
deposition, 4) 50% base cation deposition, and 5) the combination of N, S, and base cation deposition. Species changes include replacing
mixed hardwoods to loblolly pine and replacing loblolly pine with mixed hardwoods. NUCM simulations indicate that changes in
atmospheric deposition can have major effects on soil and soil-solution concentrations, but little effect on forest growth or nutrient
capital of loblolly pine and hardwood stands. This apparent contradiction is explained by marked changes in the distribution of nutrients
in the soil profile that sum up to only small changes in total pool sizes. The simulations also suggest that replacement of pines by
hardwoods (or vice versa) produces large differences in Ca uptake and accumulation by vegetation. In turn, this produces a chain of
events in soil chemistry that substantially alters the fluxes and accumulations of other nutrients in the system. Results are examined in
the context of field studies.
174. Johnson, Edward A. 2002. Industrial destruction reversed at Copper Basin. National Woodlands. 25(2): 10-13.
The history of the Copper Basin, located on the Georgia-Tennessee border, is an example of perhaps one of our nation’s worst
environmental excesses. It is also quite possibly one of our greatest recovery success stories. This article explores the reasons for the
destruction of the Copper Basin in forest beginning with the dawn of the Industrial Revolution in this country, and some of the remedies
applied.
175. Johnson, Edward A. 2002. Nearly a forest paradise: Copper Basin prior to 1800. National Woodlands. 25(3): 12-13.
In the last issue, the author detailed the industrial destruction caused by mining and smelting operations in the Copper Basin region of
southern Kentucky on the Georgia border, and the restoration efforts that have reclaimed much of the area’s viability as a forest. In this
article, he describes what the Copper Basin ecosystem looked like prior to 1800.
42
176. Johnston, John M.; Crossley, D.A., Jr. 1996. The significance of coarse woody debris for the diversity of soil mites. In:
McMinn, James W.; Crossley, D.A., Jr., eds. Biodiversity and coarse woody debris in southern forests: Proceedings of the workshop on
coarse woody debris in southern forests: effects on biodiversity; 1993 October 18-20; Athens, GA. Gen. Tech. Rep. SE-94. Asheville,
NC: U.S. Department of Agriculture, Forest Service, Southern Research Station: 82-87.
The community of mites inhabiting forest floors is rich in species but is poorly known both taxonomically and biologically.
Understanding the relationship of mite species diversity to ecosystem function depends upon better knowledge of habitat and substrate
use. Coarse woody debris (CWD) is a significant habitat variable as well as a resource for mite communities. However, little information
has been developed on the use of woody debris by mites in southern forests. As a habitat variable, CWD is a contributor to the
microenvironmental gradients that affect soil-mite distribution and abundance. As a resource variable, the importance of CWD resides in
its support of a varied fungal population and its nutrient reserves. Calcium, abundant in the bark of decaying boles and twigs, is
particularly important for Oribatid mites.
177. Jones, Benjamin C.; Harper, Craig A.; Beuhler, David A.; Minser, William G. III; Taylor, George A III. 2002. Ecology
and management of ruffed grouse in North Carolina. 2002 Annual report. Knoxville, TN: The University of Tennessee, Institute of
Agriculture Department of Forestry, Wildlife, & Fisheries. 21 p.
Spring 2003 will begin the fifth year of ruffed grouse research on the Wine Spring Creek Ecosystem Management Area (WSC). The
research project was initiated in March 1999 to investigate ruffed grouse habitat use, population dynamics, reproductive ecology, and
survival in the southern Appalachians of western North Carolina. Although studies have been conducted in Tennessee (Epperson 1988,
Boyd 1990, Pelren 1991) and north Georgia (Hale et al. 1982), this is the first grouse research effort of its kind in North Carolina. From
April 1999 to September 2002, data from WSC was contributed to a regional research effort, the Appalachian Cooperative Grouse
Research Project (ACGRP). Although the ACGRP concluded regional data collection in fall 2002, research will continue on WSC
through August 2004.
Research on WSC was designed to investigate an array of issues relevant to ruffed grouse management in the southern Appalachians. Of
particular interest on WSC is habitat use of ruffed grouse, especially as it pertains to forest stands harvested via alternative regeneration
practices (i.e., shelter wood, two-age, and group selection methods). Additional topics of interest include reproductive ecology,
population censusing, and seasonal survival. To investigate these issues, research efforts are broken into periods according to
biologically important activities of grouse (i.e. drumming, nesting, brood rearing, etc.). In this report, study progress and results from
2002 are summarized accordingly.
178. Jones, E.B. Dale, III; Helfman, Gene S.; Harper, Joshua O.; Bolstad, Paul V. 1999. Effects of riparian forest removal on fish
assemblages in southern Appalachian streams. Conservation Biology. 13(6): 1454-1465.
Deforestation of riparian zones is known to influence the numbers and kinds of organisms that inhabit adjoining streams, but little
quantitative information is available on how much deforestation must occur before the biota is affected. We sampled fishes and stream
habitats in 12 stream segments downstream from deforested but vegetated riparian patches 0-5.3 km long, all down slope from
watersheds with at least 95% forest cover. We found an overall decrease in fish abundance with increasing length of nonforested riparian
patch; sculpins, benthic minnows, and darters decreased, and sunfishes and water-column minnows increased in numbers. Introduced
species were more common downstream from longer riparian patches. Habitat diversity decreased and riffles became filled with fine
sediments as upstream patch length increased. Lengths of upstream nonforested patch and substrate particle size were much stronger
predictors of fish occurrence than riparian patch width. Faunal characteristics and physical features of the stream changed in direct
proportion to the gradient of riparian disturbance, but the abundance of several species underwent pronounced change at particular
threshold patch lengths. These results suggest that riparian forest removal leads to shifts in the structure of stream fish assemblages due
to (1) decreases in fish species that do not guard hidden eggs or that are dependent on swift, shallow water that flows over relatively
sediment-free substrates, or (2) increases in fishes that guard their young in pebble or pit nests or that live in slower, deeper water. When
watershed development is anticipated or planned, limited clearing of riparian trees may cause minor disturbance to the fish assemblage,
but streams in even a heavily forested watershed with vegetated riparian buffers cannot tolerate disruption of riparian-zone trees over
much more than 1 km in length. Riparian buffer length and area should be given stronger consideration in stream protection and
restoration plans.
179. Jones, Jeremy B., Jr. 1997. Benthic organic matter storage in streams; influence of detrital import and export, retention
mechanisms, and climate. In: Webster, J.R.; Meyer, J.L., eds. Stream organic matter budgets. Journal of the North American
Benthological Society. 16: 109-119.
This chapter is part of a multi-site analysis of organic matter dynamics in streams. Regression of benthic organic matter (BOM) and
latitude and precipitation proved useful in predicting BOM standing crop in streams at a continental scale, although BOM was also
related channel characteristics such as gradient and woody debris.
180. Jones, Julia A.; Post, David A. 2004. Seasonal and successional streamflow response to forest cutting and regrowth in the
northwest and eastern United States. Water Resources Research. 40 (WO5203, doi:10.1029/2003WR002952):1-19.
43
This study examined daily streamflow response over up to four decades in northwest conifer forest and eastern deciduous forest sites in
the United States. We used novel methods to analyze daily observations of climate and streamflow spanning more than 900 basin years
of record at 14 treated/control basin pairs where forest rem0oval and regrowth experiments were underway in the period 1930-2002. In
the 1 to 5-year period after forest removal, maximum daily increases ranged from 2 to 3 mm at deciduous forest sites, to 6 to 9 mm at
conifer forest sites. Significant spring surpluses persisted for up to 35 years in conifer forest basins, but winter and spring streamflow
deficits appeared after 10 to 15 years of forest regrowth in eastern deciduous forest basins. In all 5-yr posttreatment periods, absolute
changes in daily streamflow were significantly more likely during moist, warm seasons, or during snowmelt seasons, but relative
changes were more likely during warm seasons irrespective of moisture status. Both relative and absolute streamflow changes in the 1 to
5 and 15 to 25-year periods after forest removal were significantly positively related to the age of the forest at the time it was cut. Eastern
deciduous forests had been disturbed by logging or hurricane 12 to 56 years prior to forest removal, while Pacific Northwest conifer
forests had been not experienced logging or wildfire for 90 to 450 years. Paired basin experiments provide a continuous, and
continuously changing, record of vegetation structure, composition, and climate, and their effects on streamflow.
181. Kloeppel, B.D., Gower, S.T.; Vogel, J.G.; Reich, P.B. 2000. Leaf-level resource use for evergreen and deciduous conifers
along a resource availability gradient. Functional Ecology. 14: 281-292.
*We compared leaf-level carbon, nitrogen and water use for a deciduous (Larix occidentalis Nutt.) and sympatric evergreen
(Pseudotsuga menziesii, Beissn., Franco, or Pinus contorta Engelm.) confer along a resource availability gradient spanning the natural
range of L. occidentalis in western Montana, USA. * We hypothesized that leaf photosynthesis (A), respiration (r), specific leaf area
(SLA) and foliar nitrogen concentration (N) would be higher for deciduous than sympatric evergreen conifers in mixed stands, and that
these interspecies differences would increase from high to low resource availability. We also hypothesized that leaf-level nitrogen and
water-use efficiency would be higher for the co-occurring evergreen conifer than L. occidentalis. * In general, mass-based
photosynthesis (Am) was significantly higher for L. occidentalis than co-occurring evergreen conifers in the drier sites, but Am was
similar for evergreen and deciduous conifers at the mesic site. *Mass-based foliar nitrogen concentration (Nm) was positively correlated
to SLA for all species combined across the gradient (R2 = 0·64), but the relationship was very weak (R2 = 0·08– 0·34) for evergreen and
deciduous species separately. Mass-based Am and rm were poorly correlated to Nm for all species combined across the gradient (R2 = 0·28
and 0·04, respectively). * For each site-species combination, daily maximum Am was negatively correlated to vapor pressure deficit
(VPD) (R2 < 0·04). *Instantaneous nitrogen-use efficiency (NUEi; Am divided by Nm) and water-use efficiency (13C) increased
significantly (P = 0·05) from high to low resource availability for both evergreen and deciduous conifers, except for NUE i in L.
occidentalis.
182. Kloeppel, Brian D.; Clinton, Barton D.; Vose, James M.; Cooper, Aaron R. 2003. Drought impacts on tree growth and
mortality of southern Appalachian forests. In: Greenland, D.; Goodin, D.G.; Smith, R.C.; editors. Climate variability and ecosystem
response at long-term ecological research sites. New York, NY: Oxford University Press. 43-55. Chapter 3.
In this chapter, we describe the general climate and physical and biological features of Coweeta as well as the impact of drought on tree
growth and mortality. In particular, we focus on data from the 1985 to 1988 and 1998 to 2001 drought periods at Coweeta. We also
describe the drought impacts on tree growth rates, tree mortality caused by southern pine beetle, tree mortality caused by pathogens,
interactions with tree insects and diseases, and tree species-specific mortality. These impacts are summarized in a description of drought
as a disturbance regime. The timescale of this climate variability is annual with the potential for preexisting soil moisture conditions
either providing a buffer or further exacerbating the drought conditions.
183. Knight, Dennis H.; Vose, James M.; Baldwin, V. Clark; Ewel, Katherine C.; Grodzinska, Krystyna. 1994. Contrasting
patterns in pine forest ecosystems. Ecological Bulletins (Copenhagen). 43: 9-19.
Forests and woodlands dominated by pines (Pinus spp.) occur naturally over an unusually broad range of environmental conditions in the
northern hemisphere and now they are widely planted south of the equator. Some pine species occur in savannas that are characterized
by surface fires every 10 years of less, while others form dense forests that are burned at intervals of 100-300 years. Contrasting
disturbance, temperature, and precipitation regimes have led to great diversity in the morphological and physiological adaptations of the
numerous pine species, but most appear to be tolerant of low nutrient availability. Plant uptake and microbial immobilization lead to an
accumulation of nitrogen that is derived primarily from atmospheric deposition rather than nitrogen fixation, with the largest amount of
nitrogen stored in the soil organic matter. Available data suggest that annual net primary productivity ranges from about 200-1800 g C
m-2, with a large portion of the photosynthate allocated annually to the production of fine roots. Following disturbances, more
photosynthesis occurs in the understory and there is the potential for increased water outflow and nitrogen leaching until pre-disturbance
levels of leaf area are restored.
184. Knoepp, Jennifer D.; Coleman, David C.; Crossley, D.A., Jr.; Clark, James S. 2000. Biological indices of soil quality; an
ecosystem case study of their use. Forest Ecology and Management. 138: 357-368.
Soil quality indices can help ensure that site productivity and soil function are maintained. Biological indices yield evidence of how a
soil functions and interacts with the plants, animals, and climate that comprise an ecosystem. Soil scientists can identify and quantify
both chemical and biological soil-quality indicators for ecosystems with a single main function, such as agricultural lands and forest
44
plantations. However, quantifying these indices in complex ecosystems- that have multiple uses or goals such as maintaining
biodiversity, aesthetics, recreation, timber production, and water quality- is much more difficult. In an ecosystem context, all
components – plants, animals, and humans – interact with the soil differently, making soil quality indices variable. These interactions
result in a combination of biological processes that make each ecosystem unique. We examined the soil and site quality of five forest
stands (xeric oak-pine; two mixed hardwood, cove hardwood, northern hardwood), within the 2185-ha Coweeta Hydrologic Laboratory.
An initial rank of soil quality based on soil chemical and physical properties was assigned. The ranking was then compared with four
common groups of soil biological indicators: (1) nitrogen availability; (2) litter decomposition (3) soil microarthropod populations; and
(4) carbon availability. We also examined estimates of overstory productivity, overstory biodiversity and total aboveground productivity
for each site as indices of site quality. We found that soil and site quality rankings varied with the indicator, showing that the soil or site
of greatest quality may change depending on the use or goal of the ecosystem under examination.
185. Knoepp, Jennifer D.; Swank, Wayne T. 1997. Forest management effects on surface soil carbon and nitrogen. Soil Science
Society of America Journal. 61(3): 928-935.
Changes in surface soil C and N can result from forest management practices and may provide an index of impacts on long-term site
productivity. Soil C and N were measured over time for five watersheds in the southern Appalachians: two aggrading hardwood forests,
on south- and one north-facing, undisturbed since the 1920s; a white pine (Pinus strobus L.) plantation planted in 1956; and two
regenerating hardwood forests, a whole-tree harvest in 1980, and a commercial sawlog harvest in 1977. Soils on harvested watersheds
were sampled before and for »15 yr after harvest. Surface soil C concentration on the undisturbed watersheds varied significantly among
sample years. Concentrations fluctuated on the south facing and decreased on the north-facing watershed. The pattern for total N was
similar. Total N decreased significantly on the north facing but was stable on the south-facing watershed. In the white pine plantation, C
increased while N concentrations decreased during the 20-yr period. Soil C and N concentrations generally declined the first year
following whole-tree harvest. Fourteen years after cutting, C remained stable, while N was greater compared with reference watershed
soils. The commercial sawlog harvest resulted in large increases in surface soul C and N concentrations immediately after cutting.
Carbon levels remained elevated 17 yr following cutting. Our data suggest that the forest management practices examined do not result
in long-term decreases in soil C and N. However, the high interannual variation on all watersheds suggests that care must be taken in
selecting control sites to determine long-term treatment impacts.
186. Knoepp, Jennifer D.; Swank, Wayne T. 1997. Long-term effects of commercial sawlog harvest on soil cation concentrations.
Forest Ecology and Management. 93: 1-7.
There is increasing concern about the effects of nutrient removal associated with various forest harvesting practices on long-term site
productivity. We measured exchangeable soil cation concentration responses to a commercial clearcut sawlog harvest in mixed
hardwoods on a 59-ha watershed in the southern Appalachians. Soils were sampled 17 months prior to, and periodically for 17 years
after, harvest. Concentrations of Ca, Mg, and K, increased significantly in the 0-10 cm soil layer for 3 years following harvest compared
to pre-treatment levels. Concentrations of Mg and K were still significantly above pre-treatment levels 17-20 years following harvest.
Calcium concentrations did not change significantly at the 10-30 cm depth, but both Mg and K showed significantly higher
concentrations in some post-treatment years. Soils in the adjacent reference watershed showed no significant changes in soil cation
concentrations over the same 17-year period. Results indicate that sawlog harvest using cable-yarding techniques on these sites does not
adversely impact soil cation concentrations.
187. Knoepp, Jennifer D.; Swank, Wayne T. 1998. Rates of nitrogen mineralization across an elevation and vegetation gradient in
the southern Appalachians. Plant and Soil. 204: 235-241.
We measured nitrogen (N) transformation rates for six years to examine temporal variation across the vegetation and elevation gradient
that exists within the Coweeta Hydrologic Laboratory. Net N mineralization and nitrification rates were measured using 28-day in situ
closed core incubations. Incubations were conducted at various intervals, ranging from monthly during the growing season, to seasonally
based on vegetation phenology. Vegetation types included oak-pine, cove hardwoods, low elevation mixed oak, high elevation mixed
oak, and northern hardwoods. Elevations ranged from 782 to 1347 m. Nitrogen transformation rates varied with vegetation type.
Mineralization rates were lowest in the oak-pine and mixed oak sites averaging <1.2 mg N kg soil -1 28 day-1. Rates in the cove hardwood
site were greater than all other low elevation sites with an annual average of 3.8 mg N kg soil -1 28 day-1. Nitrogen mineralization was
greatest in the northern hardwood site averaging 13 mg N kg soil -1 28 day-1. Nitrification rates were typically low on four sites with rates
<0.5 mg N kg soil-1 28 day-1. However, the annual average nitrification rate of the northern hardwood site was 6 mg N kg soil -1 28 days 1.
Strong seasonal trends in N mineralization were observed. Highest rates occurred in spring and summer with negligible activity in
winter. Seasonal trends in nitrification were statistically significant only in the northern hardwood site. Nitrogen mineralization was
significantly different among sites on the vegetation and elevation gradient. While N mineralization rates were greatest at the high
elevation site, vegetation type appears to be the controlling factor.
188. Knoepp, Jennifer D.; Swank, Wayne T. 2002. Using soil temperature and moisture to predict forest soil nitrogen
mineralization. Biology & Fertility of Soils. 36: 177-182.
45
Due to the importance of N in forest productivity ecosystem and nutrient cycling research often includes measurement of soil N
transformation rates as indices of potential availability and ecosystem losses of N. We examined the feasibility of using soil temperature
and moisture content to predict soil N mineralization rates (Nmin) at the Coweeta Hydrologic Laboratory in the southern Appalachians.
We conducted seasonal laboratory incubations of A and AB horizon soils from three sites with mixed-oak vegetation using temperature
and moisture levels characteristic of the season in which the soils were collected. The incubations showed that temperature and
temperature-moisture interactions significantly affected net soil Nmin. We used the laboratory data to generate equations relating net
Nmin to soil temperature and moisture data. Using field-collected temperature and moisture data, we then calculated Nmin on similar
forest sites and compared predicted rates with in situ, closed-core Nmin measurements. The comparison showed that the in situ Nmin
was greater than rates predicted from laboratory-generated equations (slope =3.22; r2=0.89). Our study suggests that while climatic
factors have a significant effect on soil Nmin, other factors also influence rates measured in the laboratory and in situ.
189. Knoepp, Jennifer D.; Tieszen, Larry L.; Fredlund, Glen G. 1998. Assessing the vegetation history of three southern
Appalachian balds through soil organic matter analysis. Research Paper SRS-13. Asheville, NC: U.S. Department of Agriculture, Forest
Service, Southern Research Station. 12 p.
The history of Southern Appalachian grassy balds has long been a topic of speculation. Two types have been identified: those completely
covered by grass and those occupied by a mixed-hardwood overstory with a grassy herbaceous layer. Three areas historically known as
balds were identified in the Wine Spring Ecosystem Project Area. Each is currently under a different management regime. The objective
of this assessment was to determine the vegetative history of these balds through soil organic matter (SOM) analysis. Soil was collected
from each horizon through the profile on the bald sites using a nearby forest for reference. The d13C values were determined for the
green vegetation, litter, and soils of the bald sites and reference forests. Samples were selected for determination of phytolith and
charcoal content and for 14C dating. The d13C value of plant tissues varies with photosynthetic pathway and plant type, providing a
distinctive signature in SOM. Significant shifts in SOM d 13C values with depth in the profile would suggest changes in site vegetation.
Organic matter analysis indicated that two of the bald sites were never completely covered by grass without a woody component. The
third bald may have undergone a vegetative shift in more recent times. Data also suggest that a vegetative shift may have occurred on
two of the reference forest sites.
190. Knoepp, Jennifer D.; Vose, James M. 2002. Quantitative comparison of In Situ soil CO2 flux measurement methods. U.S.
Department Agriculture, Forest Service, Southern Research Station. Research Paper SRS-28.
Development of reliable regional or global carbon budgets requires accurate measurement of soil CO2 flux. We conducted laboratory and
field studies to determine the accuracy and comparability of methods commonly used to measure in situ soil CO2 fluxes. Methods
compared include two static techniques, sodium hydroxide (NaOH) and soda lime as CO2 traps; a multichamber open dynamic system
(OC) with an infrared gas analyzer; and a headspace analysis system, with gas chromatograph with circulating fan (GCF) and gas
chromatograph without circulating fan (GC), measuring changes in headspace CO2 concentration using a gas chromatograph. In the
laboratory, we compared NaOH, OC, GCF, and GC using sand-filled cylinders to simulate a soil system. Three concentrations of
standard CO2 gas (representing low, medium, and high soil-CO2 flux rates) entered the cylinders through individually monitored flow
meters. Flux rates measured using OC method equaled the actual CO2 flux at all three CO2 concentrations. Flux rates determined with
GC and GCF were <55 percent of the actual flux rate. The percent of actual CO2 flux measured increased with increasing CO2
concentrations. At all concentrations, NaOH collect between 40 and 47 percent of CO 2 entering the system. A field study was conducted
to verify laboratory results and allow comparison with the soda lime trap (SODA) method. In laboratory and filed studies, all methods
detected significant differences in flux rates among the standard CO2 concentrations and field sites. Regression analyses showed good
relationships between NaOH, SODA, and GC methods with flux rates measured using the CO methods (r2 ≥ 0.78). Slope values for these
regression equations ranged from 0.34 for NaOH to 0.54 for GC and SODA. These results suggest that data collected using the other
methods could be standardized to OC flux rates. However, because methodological differences significantly affect CO2 flux
measurements, care should be used in applying these relationships.
191. Knoepp, Jennifer Donaldson; Swank, Wayne T. 1995. Comparison of available soil nitrogen assays in control and burned
forested sites. Soil Science Society of America Journal. 59: 1750-1754.
The existence of several different methods for measuring net N mineralization and nitrification rates and indexing N availability has
raised questions about the comparability of these methods. We compared in situ covered cores, in situ buried bags, aerobic laboratory
incubations, and tension lysimetry on control and treated plots of a prescribed burn experiment in the southern Appalachians.
Environmental influences were examined with soil moisture and temperature measurements. All methods detected significant differences
in net N mineralization rates between treated and control plots; P = 0.04, 0.007, 0.001, and 0.07 for covered cores, buried bags, lab
incubations, and lysimeters, respectively. Mean rates of N mineralization during the growing season were similar for the three soil
incubation methods. The laboratory incubation of soil from treated plots produced significantly greater potential nitrification rates than
the in situ methods. The four methods were not well correlated; this indicates the need for caution when comparing N transformation
data derived from different methods. We conclude that the in situ covered core method is superior because it best incorporates sitespecific soil temperature and moisture changes into N transformation measurements.
46
192. Kokkonen, Teemu S.; Jakeman, Anthony J. 2001. A comparison of metric and conceptual approaches to rainfall-runoff
modeling and its implications. Water Resources Research. 37(9): 2345-2352.
The aim of the present paper is to compare metric and conceptual approaches to rainfall-runoff modeling in terms of calibration and
simulation performances and parameter invariance. This is investigated by applying two models of equal complexity (i.e. possessing the
same number of parameters), but with different levels of “conceptualization,” to two catchments with different climatology. Level of
conceptualization is understood as the degree to which the model structure and its parameters can be related to catchment-scale
hydrological processes. The results suggest that the model with less conceptualization provides, in general, a more accurate reproduction
of streamflow, even on independent data sets, but this difference only becomes clear when models are applied to the drier catchment.
The paper corroborates that the more process complexity one wants to include in the model structure, the more types of data and higher
information content are required to estimate the process parameters and to test the model performance. When only rainfall-runoff data
are available, it is difficult to justify substantial conceptualization of complex processes.
193. Kokkonen, Teemu S.; Jakeman, Anthony J.; Young, Peter C.; Koivusalo, Harri J. 2003. Predicting daily flows in ungauged
catchments: model regionalization from catchment descriptors at the Coweeta Hydrologic Laboratory, North Carolina. Hydrological
Processes: 17: 2219-2238.
Regionalization approaches to daily streamflow prediction are investigated for 13 catchments in the Coweeta Hydrologic Laboratory
using a conceptual rainfall-runoff model of low complexity (six parameters). Model parameters are considered to represent the dynamic
response characteristics (DRCs) of a catchment. It is demonstrated that all catchments within the region cannot be assumed to have a
similar hydrological behaviour, and thence a regionalization approach considering differences in physical catchment descriptors (PCDs)
is required. Such a regionalization approach can be regarded as a top-down method, in the sense that factors controlling parameter
variability are identified first within the entire region under study, and then such information is exploited to predict runoff in a smaller
sub-region. Regionalization results reveal that consideration of interrelations between dependent variables, which here are the parameters
of the rainfall-runoff model, can improve performance of regression as a regionalization method. Breaking the parameters correlation
structure inherent in the model, and exploiting merely relationships between model parameters and PCDs (no matter how weakly related
they are), can result in a significant decrease in regionalization performance. Also, high significance of regression between values of
PCDs and DRCs does not guarantee a set of parameters with a good predictive power. When there is a reason to believe that, in the sense
of hydrological behaviour, a gauged catchment resembles the ungauged catchment, then it may be worthwhile to adopt the entire set of
calibrated parameters from the gauged catchment instead of deriving quantitative relationships between catchment descriptors and model
parameters.
194. Koppes, Steven N. 1998. Down in the dirt. University of Georgia Research Reporter. Athens, GA. University of Georgia: 28(1):
7-14.
In recent decade’s drought, insect outbreaks, plant disease, and even a hurricane have afflicted the Coweeta watershed just three miles
north of the Georgia border. But UGA and other researchers have discovered that these relatively rare, seemingly damaging events
actually replenish the ecosystem with important nutrients.
195. Laerm, Joshua; Brown, Eric; Lepardo, Lisa; Menzel, Michael A.; Ford, William M. 1996. Distributional occurrence and
status of the least shrew (Crytotis parva) in the southern Appalachians. Georgia Journal of Science. 53: 189-194.
The first records of least shrew, Cryptotis parva are reported from the Blue Ridge and Ridge and Valley Provinces of Georgia. Review
of distributional records of the least shrew throughout the Appalachian Highlands of Alabama, Georgia, North Carolina, South Carolina,
and Tennessee indicate it to be widely distributed, but uncommon to rare regionally.
196. Laerm, Joshua; Ford, W. Mark; Chapman, Brian R. 1996. New records of Zapus hudsonius and Napaeozapus insignis
(Rodentia: Zapodidae) from Georgia with comments on their conservation status. Georgia Journal of Science. 53: 99-108.
New records of Zapus hudsonius and Napaeozapus insignis are reported from Georgia, including the southernmost record of the latter
from Lumpkin County. The conservation status of Zapus and Napaeozapus are reviewed in a regional context. Zapus is uncommon to
rare throughout Georgia and adjacent regions of the Southeast. Napaeozapus is common in appropriate habitat in Georgia and adjacent
regions of the Southeast.
197. Laerm, Joshua; Ford, William M.; Weinand, Daniel C. 1994. Additional records of the pygmy shrew, Sorex hoyi winnemana
Preble (insectivora: Soricidae), in western North Carolina. Brimleyana. 21: 91-96.
Additional records of the pygmy shrew, Sorex hoyi winnemana Preble, are reported from 14 localities in 7 counties of western North
Carolina. Results of recent surveys in adjacent regions of Tennessee and Georgia indicate that the species is widely distributed in the
extreme southern Appalachian Mountains, including North Carolina, but is nowhere abundant.
47
198. Laerm, Joshua; Menzel, Michael A.; Wolf, Dorothy J.; Welch, James R. 1997. The effect of riparian zones in structuring
small mammal communities in the southern Appalachians. In: First Biennial North American Forest Ecology Workshop: 1997 June 2426: Raleigh, NC: 132-145.
Riparian zones have been shown to be important in structuring vertebrate communities and in maintaining biodiversity. We examined
the role of riparian zones in structuring small mammal communities in a Southern Appalachian watershed at Coweeta Hydrological
Laboratory, Macon County, North Carolina. We established pitfall and live-trap grids in three replicates each of seeps, first-order,
second-order, and third-order stream riparian zones. We established upland non-riparian controls for each replicate at a distance greater
that 100 m from the respective riparian zones. These sites were distributed over northern hardwood, cove hardwood, moderate oak, and
xeric-oak-pine cover types along an elevational gradient from 678 to 1,592 m. We found no significant differences in the composition of
small mammal communities between riparian and non-riparian zones at these sites. Patterns of species richness, diversity, and evenness
for both pitfall surveys and live trapping estimators were similar for riparian and non-riparian areas. Within-stream order comparisons
yielded similar results; no differences were found between riparian and non-riparian sites for seeps, second-order, or third-order streams.
The only exception was in first-order stream comparisons where Blarina brevicauda was found to be more abundant in non-riparian
sites. The lack of significant differences between riparian and non-riparian site in small mammal parameters examined would appear to
be associated with the general lack of structural and vegetative distinction between riparian and nonriparian zones in the southern
Appalachians.
199. Lakly Michelle, B.; Crossley, D.A., Jr. 2000. Tullgren extraction of soil mites (Acarina): Effect of refrigeration time on
extraction efficiency. Experimental and Applied Acarology. 24: 135-140.
Soil microarthropod constitutes one of the most species rich communities in forest ecosystems (Crossley & Glair, 1991). The effects of
soil fauna in these systems on decomposition rates, nutrient regeneration, and soil structure have been well documented; however,
dependable estimates of population size and community structure largely depend upon adequate sampling (Anderson, 1988; Seastedt &
Crossley, 1988). Problems inherent in sampling microarthropod include their patchy distribution, large abundance, and minute size. In
practice, microarthropod sampling involves collection of leaf litter or soil, which is returned to the laboratory for extraction by one of
two methods: flotation or Tullgren extraction.
200. Lamberti, Gary A.; Steinman, Alan D. 1997. A comparison of primary production in stream ecosystems. In: Webster, J.R.;
Meyer, J.L., eds. Stream organic matter budgets. Journal of the North American Benthological Society. 16: 95-104.
This chapter is part of a multi-site analysis of organic matter dynamics in streams. Watershed area was the best predictor of gross
primary productivity (GPP), which increased with increasing watershed area. Watershed area, discharge, and SRP concentration
explained 71% of the variation in GPP.
201. Lamoncha, K.L.; Crossley, D.A., Jr. 1998. Oribatid mite diversity along an elevation gradient in a southeastern Appalachian
forest. Pedobiologia. 42: 43-55.
The abundance and diversity of oribatid mites in soil and litter was investigated at five sites along an elevation gradient of forest types at
Coweeta Hydrologic Laboratory, Macon County, North Carolina, USA. A total of 135 species was collected from the five sites.
Diversity indices suggested an increase in oribatid species diversity with increasing elevation. A single, very rich oribatid mite
community was found over the entire elevation gradient, although the distribution of less abundant species differed between the sites.
The two sites with lower abundances had higher species diversity indices. Lower abundance of soil oribatid mites may be characteristic
of southeastern Appalachian sites, which are mature or approaching maturity. The largest number of species was found for mixed oak
communities, the predominant vegetation type at Coweeta.
202. Lei, Thomas T.; Semones, Shawn W.; Walker, John F.; Clinton, Barton D.; Nilsen, Erik T. 2002. Effects of Rhododendron
Maximum thickets on tree seed dispersal, seedling morphology, and survivorship. International Journal of Plant Sciences. 163(6): 9911000.
In the southern Appalachia forests, the regeneration of canopy trees is severely inhibited by Rhododendron maximum L., an evergreen
understory shrub producing dense thickets. While light availability is a major cause, other factors may also contribute to the absence of
tree seedlings under R. maximum. We examined the effects of R. maximum on several life history stages of tree species, including seed
dispersal, seed bank germination, seedling growth, and survivorship. We found no significant effect of R. maximum on seed reaching the
forest floor for Acer rubrum, Liriodendron tulipifera, Quercus rubra, Quercus prinus, Carya spp., and Nyssa sylvatica. This indicates
that either seed output of maternal trees rooted within the thicket were unaffected by R. maximum or seed dispersal from surrounding
areas into thickets compensated for a lower seed production of canopy trees rooted in the thickets. Germination of tree seeds (A. rubrum,
L. tulipifera, Q. rubra, and Betula lenta) from the seed bank also was not reduced by leaves and substrates within the thickets. Seedling
mortality of all species (Q. rubra, Prunus serotina, and Tsuga canadensis) planted in our experimental plots was up to fivefold higher in
thickets of R. maximum compared with those outside the thickets. The order of mortality under the R. maximum thickets,
Prunus>Quercus>Tsuga, was consistent with the shade tolerance ranking of these species. Loss of Tsuga seedlings was attributed to
burial by litter rather than shade. Surviving seedlings of Quercus and Prunus in R. maximum thickets, but the seedlings in R. maximum
48
thickets produced significantly fewer leaves, smaller total leaf area, leaf mass, and stem mass. Leaf N (%) was significantly higher in
Quercus seedlings in R. maximum thickets compared with seedlings outside the thickets. Moreover, no difference was found in leaf N
(%) between forest types for Prunus and Tsuga, indicating that seedlings in R. maximum thickets were not N limited. Rather, light
limitation, herbivory, and litter fall contributed to the lack of tree regeneration under R. maximum thickets.
203. McCay, Timothy S.; Durden, Lance A. 1996. Ticks and fleas of shrews in Appalachian. Georgia and North Carolina. Journal of
Parasitology. 82(4): 666-667.
Ticks (Acari: Ixodidae) and fleas (Insecta: Siphonaptera) were recovered from 8 smoky shrews, Sorex fumeus Miller, and 9 northern
short-tailed shrews, Blarina brevicauda (Say), trapped at elevations of 720-1,310 m in Macon and Jackson counties in western North
Carolina and Union County in northern Georgia from April 1994 to August 1995. The ticks Ixodes angustus Neumann and Ixodes woodi
Bishopp, and the flea Corrodopsylla curvata (Rothschild), were recovered from smoky shrews. The same 2 tick species, in addition to
the fleas, Ctenophthalmus pseudagyretes Baker and Doratopsylla blarinae Fox, were recovered from northern short-tailed shrews. New
state records for I. angustus from Georgia and I. woodi from North Carolina are established.
204. McMinn, James W.; Crossley, D.A., Jr., eds. 1996. Biodiversity and coarse woody debris in southern forests, proceedings of
the workshop on coarse woody debris in southern forests: Effects on biodiversity; 1993 October 18-20; Athens, GA. Gen. Tech. Rep.
SE-94. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 146 p.
Seventeen papers address the current state of knowledge about the influences of coarse woody debris (CWD) on the biodiversity of
various groups of biota. The generation of CWD, its accumulation on forest floors, and its distribution are functions of stand age and
management in the South. The effects of CWD on biodiversity depend upon harvesting variables, distribution, and dynamics. Research
priorities are identified for future studies that should provide a basis for the conservation of biodiversity when interacting with
appropriate management techniques.
205. McMinn, James W.; Hardt, Richard A. 1996. Accumulations of coarse woody debris in southern forests. In: McMinn, James
W.; Crossley, D.A., Jr., eds. Biodiversity and coarse woody debris in southern forests: Proceedings of the workshop on coarse woody
debris in southern forests: Effects on biodiversity; 1993 October 18-20; Athens, GA. General Technical Report SE-94. Asheville, NC:
U.S. Department of Agriculture, Forest Service, Southern Research Station: 1-9.
Accumulations of coarse woody debris (CWD) were estimated from Forest Inventory and Analysis information for Georgia and South
Carolina and from the literature covering detailed studies. Mean accumulations by broad ownership class and forest type for Georgia and
South Carolina ranged from 2.2 to 10.7 mega grams per hectare (Mg/ha). Accumulations in individual studies ranged from 0.4 Mg/ha in
mature pitch pine on poor sites to 91.2 Mg/ha in young cove hardwoods regenerated by clearcutting. The information presented in this
review suggests that attempts to quantify CWD accumulations should account for physiography, ownership, forest type, stand age, stand
origin (artificial vs. natural), and disturbance.
206. McNab, W. Henry; Browning, Sara A.; Simon, Steven A.; Fouts, Penelope E. 1999. An unconventional approach to
ecosystem unit classification in western North Carolina, USA. Forest Ecology and Management. 114: 405-420.
We used an unconventional combination of data transformation and multivariate analyses to reduce subjectivity in identification of
ecosystem units in a mountainous region of western North Carolina, USA. Vegetative cover and environmental variables were measured
on 79 stratified, randomly located, 0.1 ha sample plots in a 4000 ha watershed. Binary transformation of percent cover followed by direct
and indirect ordination indicated the 185 inventoried species were associated primarily with soil A-horizon thickness, soil base
saturation, and aspect. Redundant cluster analyses, consisting of divisive and agglomerative methods for multivariate classification of
core plots, followed by selective discriminant analysis of remaining non-core plots, indicated that the continuum of vegetation and
environment could be grouped into five ecosystem units. Approximately 20 herbaceous, shrubs, and tree species and several soil and
topographic variables were highly significant discriminators of ecosystem units. We also demonstrated that redundant cluster analysis
may be used to subdivide ecosystem units into subunits of uniform understory composition and associated environment. Validation and
refinement of classification units, linkage with faunal biological components, and arrangement into landscape areas suitable for resource
management is needed before field application.
207. McNulty, S.G.; Swank, W.T. 1995. Wood 13C as a measure of annual basal area growth and soil water stress in a pinus strobus
forest. Ecology. 76(5): 1581-1586.
The relationship between annual wood tissue 13C, growing season soil water potential, and basal area growth were studied in a mature,
white pine stand at Coweeta Lab. In 1992, four bolewood cores that spanned the years from 1980 to 1989 were extracted from each of
ten equal-size, co-dominant white pine trees within the stand. The 1980s were a time of extreme climate with some of the hottest, driest,
and wettest years recorded at Coweeta. Annual basal area growth ranged from 14.5 to 25.0 cm2tree-1yr-1, and modeled values of average
growing season soil water potential ranged from -0.21 to -5.58 MPa, when measured to a depth of 60 cm. After correcting annual wood
tissue 13C for atmospheric changes in 13C, carbon isotopic discrimination ranged from 18.52 to 19.62%. The discrimination of annual
wood tissue was positively correlated with average growing season soil water potential and average annual basal area growth. Basal area
49
growth and growing season soil water potential were also correlated. These results suggest that annual wood tissue 13C could potentially
be useful in estimating historic changes in soil water potential and basal area growth in mature forest ecosystems.
208. McNulty, S.G.; Swank, W.T. 1996. Forest ecosystem analysis using a GIS. In: Proceedings of eco-informa `96: global networks
for environmental information; 1996 November 4-7; Lake Buena Vista, FL; Vol. 10; Ann Arbor, MI: Environmental Research Institute
of Michigan: 167-172.
Forest ecosystem studies have expanded spatially in recent years to address large-scale environmental issues. We are using a geographic
information system (GIS) to understand and integrate forest processes at landscape to regional spatial scales. This paper presents three
diverse research studies using a GIS. First, we used a GIS to develop a landscape scale model to predict forest soil erosion rates given
alternative forest management practices and weather conditions. Second, a GIS was used to evaluate the cumulative impacts of land use
practices on water quality for a 4350 ha basin. Third, we used a GIS to store and manipulate complex databases for modeling the
influence of climate change on forest hydrology and productivity across the southern U.S. We anticipate the demand for GIS techniques
will greatly increase because of the need to address increasingly complex ecosystem questions.
209. McNulty, S.G.; Swift, L.W., Jr.; Hays, J.; Clingenpeel, A. 1995. The use of a GIS for assessing management alternatives to
reduce over-land sediment production and transport. [Microfiche] Presented at 1995 ASAE annual international meeting; 1995 June 1923; Chicago, IL. Paper No. 95-2701. St. Joseph, MI: American Society Agricultural Engineers: 11 p.
Soil erosion models can be coupled with a geographic information system (GIS) to provide increased spatial resolution of soil erosion
prediction, while reducing the time needed for model parameterization. We used a GIS, a simple soil sediment prediction model (i.e.
USLE), and a simple sediment transport model, to predict soil erosion on 900 m2 grids across a 1500 ha watershed, for two alternative
logging road management practices. Although simple sediment production models have few input parameters, and do not provide
extremely accurate estimates of absolute soil loss, these models have utility for comparing alternative management practice effects on
relative changes in soil loss. Additionally, the combination of the USLE with a GIS, to predict areas with a high potential for soil loss,
could be used to alert land managers to areas where additional soil erosion mitigation is necessary. The managers can then use more
detailed and accurate, although data intensive, models such as WEPP in these potential problem areas to predict soil erosion rates more
accurately. We concluded that a GIS can be coupled with a simple soil sediment model to assess relative differences in soil erosion given
two management scenarios, and to help locate areas within watersheds where more detailed assessment of soil loss is needed.
210. McNulty, S.G.; Vose, J.M.; Swank, W.T. 1996. Loblolly pine hydrology and productivity across the southern United States.
Forestry Ecology and Management. 86: 241-251.
Concern over future changes in water yield and timber production in southern pine forests has increased the need for a well-tested and
validated forest ecosystem model, which can be used to predict potential climate change effects on forest processes. However, before a
model is used to project potential climate change impacts on forests, it should first be validated across a wide range of climates and site
conditions. We used PnET-IIS, a physiologically based, monthly time-step model that uses soil, vegetation, and climate parameter inputs
to predict evapotranspiration, drainage, soil water stress, and net primary productivity for loblolly pine stands across the southern United
States. Sensitivity analyses and model validation of predicted net primary productivity (NPP) were conducted. Predicted hydrology and
productivity were most sensitive to temperature driven parameters. Values of PnET-IIS predicted NPP were compared with measured
annual site basal area growth from 12 stands located from eastern Texas to eastern Virginia, from the year of site canopy closure to 1990.
Annual basal area growth ranged from 4.2 to 26.8 cm2 per tree year-1. Annual basal area growth was significantly correlated with
predicted NPP, and the correlation improved when annual basal area growth was averaged by site. Total annual precipitation was the
single climate variable which best correlated with annual basal area growth. These results indicate that PnET-IIS could be useful in
predicting the effect of changing patterns of precipitation and air temperature on southern pine hydrology and productivity.
211. McNulty, S.G.; Vose, J.M.; Swank, W.T.; Aber, J.D.; Federer, C.A. 1994. Regional-scale forest ecosystem modeling:
database development, model predictions, and validation using a geographic information system. Climate Research. 4: 223-231.
Arc-Info GIS and the PnET-IIS forest ecosystem model were used to predict and validate annual drainage and net primary productivity
(NPP) on a 0.5o x 0.5o grid (approximately 50 x 75 km) for southern pine forests in the state of Georgia, USA. PnET-IIS is a lump-sum
physiological model, which used historic climate data from 1951 to 1984, along with soil water-holding capacity and species-specific
vegetation characteristics. Annual predictions of drainage were well correlated with measured United States Geological Survey (USGS)
drainage (r = 0.87, p < 0.0001), and predicted NPP was related with Forest Inventory Assessment (FIA) growth data collected across the
state (r = 0.84, p < 0.0001). This study demonstrated the utility of a GIS in broad-scale ecosystem modeling and suggests that the need
for model/GIS interfacing in future research will continue to increase.
212. McNulty, Steven; Swift, Lloyd, Jr.; Hays, John; Clingenpeel, Alan. 1995. Predicting watershed erosion production and overland sediment transport using a GIS. In: Carrying the torch for erosion control: An Olympic task. Proceedings, XXVI International
erosion control association conference. 1995 February 28-March 3; Atlanta, GA. Steamboat Springs, CO: International Erosion Control
Association: 397-406.
50
Soil erosion from forested lands can seriously degrade stream water quality. Sediment production and over-land sediment transport
models have been developed which predict ecosystem management impacts on soil erosion and movement across watersheds. The
predictions of soil erosion are for whole watersheds, not for points within the watershed. Soil erosion and transport models are usually
run independently. From a spatial perspective, the models are difficult to define and the output is difficult to interpret. Our research
utilizes a user friendly, modular based, Geographic Information System (GIS) for predicting soil erosion and over-land sediment
transport under a variety of management practices including road building, timber harvesting, burning, and creation of wildlife food
plots, given a range of storm intensities broken into four seasons (i.e., spring, summer, fall, winter). Through the use of a GIS, model
predictions of sediment can be spatially distributed across the watershed and displayed as map outputs of eroded soil deposition. The
major objective of this paper is to demonstrate how a GIS and a modular modeling approach can be used by land managers to develop
alternative management scenarios for cumulative effects assessment in forested watersheds. As improved soil erosion and transport
models are developed, new models can be easily exchanged with current models using a GIS as an integrating database tool.
213. McNulty, Steven G.; Aber, John D.; Newman, Steven D. 1996. Nitrogen saturation in a high elevation New England spruce-fir
stand. Forest Ecology and Management. 84: 109-121.
High rates of nitrogen deposition were first postulated as a cause of N saturation and spruce mortality during the 1980s. To test this
hypothesis, N addition plots were established in 1988, in a high elevation spruce-fir forest in southeastern Vermont, an area of relatively
low N deposition (5.4 kg N ha-1 year-1). Four replicated treatment plots received NH4Cl-N or NaNO3-N at rates ranging from 15.7 to 31.4
kg N ha-1 year-1. The N was applied in three equal doses each year between June and August from 1988 to 1994. Two control plots were
established. Spruce, fir, and birch trees on the N addition plots receiving <20 kg N ha -1 year-1 had the highest rate of basal area growth
between 1988 and 1990 and then had the highest rate of decline between 1991 and 1994. Spruce, fir, and birch trees on the N addition
plot receiving > 25 kg N ha-1 year-1 showed moderate rated of decline from 1988 to 1994. Numerous birch and maple sprouts were noted
on the sites with the highest rates of decline, but no spruce or fir seedlings were observed. In July 1994, net N mineralization potential
was highest on control plots. A strong positive correlation existed between forest floor %N and net nitrification potential. Results suggest
that N saturation has caused foliar nutrient imbalances and that the stands may be changing in species composition and structure. No
long-term effects of N-form additions on N saturation and forest health were observed. Continued N additions may change the stands
from a slow growing and slow N-cycling coniferous forest, to a fast N-cycling and fast growing deciduous forest.
214. McNulty, Steven G.; Lorio, Peter L., Jr.; Ayres, Matthew P.; Reeve, John D. 1998. Predictions of southern pine beetle
populations using a forest ecosystem model. In: Mickler, Robert A.; Fox, Susan, eds. The productivity and sustainability of southern
forest ecosystems in a changing environment. Ecological Studies, vol. 128. New York, NY: Springer-Verlag: 617-634.
The Southern Pine Beetle (SPB) is the most important commercial pest in the southern United States. Between 1960 and 1990, the SPB
caused 900 million dollars in lost revenues across the region. The potential impact of SPB under conditions of climate change is not well
understood. Loblolly pine (Pinus taeda) is a chief host of the SPB and tree mortality is dependent on the trees ability to produce
oleoresin that deters beetle colonization. Oleoresin production is a complex function of competition within the plant for the use of carbon
in primary growth (e.g., root and stem growth) or secondary compounds (e.g. oleoresin production). Two important factors regulating the
proportion of these two carbon products are soil water stress and net primary productivity (NPP). In this paper, we explore the use of the
forest process model PnET-IIS to predicted oleoresin production as a function of NPP and soil water stress, and test the model with SPB
population data from Walker County Texas. The PnET-IIS model accurately predicts 12 years of annual SPB population change at this
site. Next, the model is applied to two climate change scenarios. One scenario predicts moderate (+3.1°C) warming while the other
predicts extreme (7.5°C) warming. The model predicts that with moderate warming loblolly pine could better resist SPB attack because
of shift in increased secondary growth compounds, and that SPB damage would be reduced. However, under extreme warming, the trees
would not produce sufficient oleoresin and SPB damage would significantly increase.
215. McNulty, Steven G.; Sun, Ge. 1998. The development and use of best practices in forest watersheds using GIS and simulation
models. In: Proceedings of the international symposium on comprehensive watershed management. 1998 September 7-10. Beijing,
China. International Research and Training Center on Erosion and Sedimentation. 391-398.
Forest watersheds provide timber and water, wildlife and fisheries habitat, and recreational opportunities. However, not an entire
watershed is equally suited for each activity. Steeper slopes may be better left forested and used for wildlife habitat while more gentle
slopes of the watershed could be used for timber production. Logging steep slopes can lead to soil erosion that can seriously degrade
stream water quality and reduce long-term site productivity. Best Management Practices (BMP's) are forest practices designed to
minimize negative environmental impacts caused by human forest use. The difficulty in developing BMP’s arises when multiple
objectives are applied to a single watershed. The objective of this research was to maintain long-term steam water quality, fisheries and
timber productivity, while minimizing soil erosion and negative water quality impacts associated with forest management. Computer
simulation models and a geographic information system (GIS) were used to create management scenarios that test how a watershed
could best be managed to maximize its multiple potential use. Our research used a 1143-ha forest watershed in western North Carolina,
USA. Basin elevations range from 920 m to 1655 m. We combined a GIS; three desired future conditions, the Universal Soil Loss
Equation (USLE) and a terrestrial transport model to predict BMP's for the watershed. Through the use of a GIS, model predictions of
sediment production and transport can be spatially distributed across the watershed and displayed as map outputs of soil movement. This
paper demonstrates how land managers could identify BMP's using a GIS-based modeling system. Once identified, alternative
51
management scenarios can be developed to assess the cumulative effects of management practices on forested watershed health and
sustainability.
216. McNulty, Steven G.; Swank, Wayne T. 1996. The use of modeling and GIS in forest ecosystem management: two case studies.
In: Arthaud, Greg J.; Hubbard, William C., eds. So For GIS '96: Proceedings of the southern forestry geographic information systems
conference; 1996 December 11-13; Athens, GA. The University of Georgia Press: 381-390.
Geographic information systems (GIS's) and ecosystem models are powerful tools for predicting the influence of environmental change
on forests. When combined, these tools assist the land manager in examining how forest practices or perturbations modify ecosystem
processes. This paper presents two examples of how land managers can use GIS/modeling outputs for forestland management planning
purposes. First, we examined the use of a soil erosion model supported within a GIS to enable the land manager to evaluate the amount
and spatial distribution of soil erosion for proposed management activities such as road construction and logging. This system could be
used for risk assessment of the effects of alternative management scenarios on stream water quality. Second, we examined the use of a
GIS and a forest process model (PnET-IIS) in assessing the influence of short and long-term climate change on forest productivity at the
regional scale. This analysis could be used by forest managers to estimate the impact of short-term climate on timber production. The
system could also be used to generate alternative, long-term silvicultural prescriptions and planning associated with species response to
climate change scenarios.
217. McNulty, Steven G.; Vose, James M.; Swank, Wayne T. 1996. Potential climate change effects on loblolly pine forest
productivity and drainage across the southern United States. Ambio. 25(7): 449-453.
PnET-IIS, a well-validated, physiologically based, forest ecosystem model combined soil and vegetation data with six climate change
scenarios. The model predicted annual net primary productivity and drainage on loblolly pine sites in the southern US states of Texas,
Mississippi, Florida, and Virginia. Climate scenario air temperature changes were +2 oC to 7oC> historic (1951 to 1984) values and
climate scenario precipitation changes were -10% to +20% > historic values. Across the sites, increasing air temperature would have
much greater impact on pine forest hydrology and productivity than would changes in precipitation. These changes could seriously
impact the structure and function of southern United States forests by decreasing net primary productivity and total leaf area. Water use
per unit area would increase, but total plant water demand would decrease because of reduced total leaf area, thus increasing regional
pine forest drainage. An average annual air temperature increase of 7oC caused a considerable reduction in the loblolly pine range.
218. McNulty, Steven G.; Vose, James M.; Swank, Wayne T. 1997. Regional hydrologic response of loblolly pine to air
temperature and precipitation changes. Journal of the American Water Resources Association. 33(5): 1011-1022.
Large deviations in average annual air temperatures and total annual precipitation were observed across the southern United States
during the last 50 years, and these fluctuations could become even larger during the next century. We used PnET-IIS, a monthly timestep forest process model that uses soil, vegetation, and climate inputs to assess the influence of changing climate on southern U.S. pine
forest water use. After model predictions of historic drainage were validated, the potential influences of climate change on loblolly pine
forest water use were assessed across the region using historic monthly precipitation and air temperature, which were modified by two
general circulation models (GCMs). The GCMs predicted a 3.2oC to 7.2oC increase in average monthly air temperature, a -24 percent to
+31 percent change in monthly precipitation and a -1 percent to +3 percent change in annual precipitation. As a comparison to the
GCMs, a minimum climate change scenario using a constant 2oC increase in monthly air temperature and a 20 percent increase in
monthly precipitation was run in conjunction with historic climate data. Predicted changes in forest water drainage were highly
dependent on the GCM used. PnET-IIS predicted that along the northern range of loblolly pine, water yield would decrease with
increasing leaf area, total evapotranspiration, and soil water stress. However, across most of the southern U.S., PnET-IIS predicted
decreased leaf area, total evapotranspiration, and soil water stress. However, across most of the southern U.S., PnET-IIS predicted
decreased leaf area, total evapotranspiration, and soil water stress with an associated increase in water yield. Depending on the GCM and
geographic location, predicted leaf area decreased to a point, which would no longer sustain loblolly pine forest, and thus indicated a
decrease in the southern most range of the species within the region. These results should be evaluated in relation to other changing
environmental factors (i.e., CO2 and O3), which are not present in the current model.
219. McNulty, Steven G.; Vose, James M.; Swank, Wayne T. 1997. Scaling predicted pine forest hydrology and productivity across
the southern United States. In: Quattrochi, Dale A.; Goodchild, Michael F., eds. Scale in remote sensing and GIS. Boca Raton. CRC
Press, Inc.: 187-209. Chapter 9.
The amount of predictive error associated with data aggregation is dependent on the scale for which models are developed and applied.
We compared the predictive capability of the ecosystem-level model PnET-IIS with measured forest growth and hydrology from three
spatial scales. PnET-IIS predictions of drainage and ET were poorly correlated with stand-level measured data and predictions of
hydrology using the stand-level hydrologic model PROSPER. The lack of a deep soil water storage term and daily to monthly
aggregation of the climate data reduced the accuracy of stand-level predictions of hydrology. PnET-IIS was a better predictor of forest
growth at the ecosystem-level. Regional predictions of drainage were well correlated with measured regional-scale stream flow, and FIA
measured loblolly pine growth was correlated with predicted NPP. The model was insensitive to SWHC and climate spatial aggregation.
Predictions of NPP and forest hydrology were not always well correlated with measured processes for each site, but the model predicted
52
generally well across all sites. The aggregation of both the input data and validation data may have biased the model predictive accuracy
and our ability to assess the models' performance. Temporal and spatial aggregation can substantially influence model predictions and
should be considered when applying or validating a model across multiple scales.
220. McNulty, Steven G.; Vose, James M.; Swank, Wayne T. 1998. Predictions and projections of pine productivity and hydrology
in response to climate change across the southern United States. In: Mickler, Robert A.; Fox, Susan, eds. The productivity and
sustainability of southern forest ecosystems in a changing environment. Ecological Studies, vol. 128. New York, NY: Springer-Verlag:
391-405. Chapter 22.
Across the Southern United States, forest timber and pulpwood rank as either the first or second most important agricultural crop for
most states. Additionally, timber from this region supplies the country with a third of the total needed timber supply, and this percentage
is expected to increase during the next century. Pressure on water supplies is also expected to increase during the next century as the
population continues to migrate to the southeastern US. Improved understanding of environmental stress impacts on regional forest
productivity and hydrology are needed to assure sound management and availability of these resources in the 21 st century. Global
warming represents a potential threat to the regional and national timber supply and water availability. This paper explored the potential
impact of four static general circulation models on loblolly pine (Pinus taeda) productivity and hydrology across the southeastern US
using the forest process model PnET-IIS. PnET-IIS is lumped parameter model that requires climate, soils, and vegetation data to predict
monthly changes in net primary productivity, soil water stress, evapotranspiration, and runoff across the southern US on a 40 x 50 km
grid cell resolution. The GCM predicted temperature increases ranged from 3.1 to 7.5°C. The wide variation in GCM inputs resulted in a
wide range of potential climate change impacts. Generally, the greater the increase in temperature, the greater the predicted loss of NPP
within the region. Average annual NPP decreased by 46%, ET decreased by 80% and drainage increased by 82% across the southern
United States.
221. McTammany, M.E.; Webster, J.R.; Benfield, E.F.; Neatrour, M.A. 2003. Longitudinal patterns of metabolism in a southern
Appalachian river. Journal of the North American Benthological Society. 22(3): 359-370.
We investigated longitudinal patterns of ecosystem metabolism (primary production and respiration) at 4 sites along a 37-km segment of
the Little Tennessee River (LTR), North Carolina. These sites corresponded to 4th- to 6th-order reaches in the LTR in an attempt to
identify the transition from heterotrophic to autotrophic conditions in this river ecosystem. In addition, we compared autochthonous C
production to supply of coarse organic material from direct litter fall and entrainment from the floodplain during floods to determine the
contributions of each to river energetics on an annual basis. Metabolism was measured at several times of year at each site using the
single-station diel oxygen change method and reaeration estimated by the energy dissipation method. Gross primary production (GPP)
ranged from 0.07 to 1.92 g C m-2 d-1 and increased ~3-fold from upstream to downstream. Respiration (R) ranged from 0.27 to 2.32 g C
m-2 d-1 but did not change along the river continuum. Net ecosystem production (NEP) and P/R consistently showed that metabolism was
heterotrophic in upstream sites and became autotrophic in the site furthest downstream. Calculated transitional P/R (i.e., where
heterotrophic respiration is supported equally by autochthonous and allochthonous C sources) suggested that this heterotrophyautotrophy shift occurred further upstream than where P/R = 1. Annual rates of GPP were 3 times higher than litter fall and floodplain
inputs of C, but R was higher than total C input suggesting that unmeasured C sources must be important for C dynamics in the LTR.
The difference between measured C inputs and R decreased along the river continuum because of a 3-fold increase in GPP with little
change in allochthonous input and R. Our results suggest that the LTR changes from heterotrophic to autotrophic along this stretch of
river and that autochthonous C sources become more important for respiration and secondary production at downstream sites.
222. Maass, Jose' Manuel; Vose, James M.; Swank, Wayne T.; Martinez-Yrizar, Angelina. 1995. Seasonal changes of leaf area
index (LAI) in a tropical deciduous forest in west Mexico. Forest Ecology and Management. 74: 171-180.
Light canopy transmittance and the Beer-Lambert equation were utilized to assess monthly leaf area index (LAI) of a tropical deciduous
forest ecosystem on the west coast of Mexico. The light transmittance coefficient (k) was obtained by analyzing vertical leaf and light
distribution in the forest canopy. An independent LAI estimate was obtained using litterfall data. The calculated k value was
0.610±0.035 (standard error). Average maximum LAI obtained with litterfall data was 4.2±0.4m2m-2. There was a significant correlation
between litter-LAI estimations and those obtained with the Beer-Lambert equation. The regression explained 95% of the variation;
however, light-LAI overestimated litter-LAI by a constant of 0.87±0.12 m2m-2. The discrepancy is partially attributed to leaf retention of
the few evergreen species, and perhaps leaf retention of a few deciduous species beyond the end of the litterfall collection. Maximum
annual LAI was similar in both study years. Minimum LAI showed considerable variation between years with similar values in the dry
seasons of 1990 and 1991, but much higher values in 1992. The difference is probably attributed to an atypical rainfall event in January
1992 (644 mm), which retarded leaf abscission.
223. Martin, Jonathan G.; Kloeppel, Brian D; Schaefer, Tara L.; Kimbler, Darrin L.; McNulty, Steven G. 1998. Aboveground
biomass and nitrogen allocation of ten deciduous southern Appalachian tree species. Canadian Journal of Forest Research. 28: 16481659.
Allometric equations were developed for mature trees of 10 deciduous species at the Coweeta Hydrologic Laboratory in western North
Carolina, U.S.A. These equations included the following dependent variables: stem wood mass, stem bark mass, branch mass, total wood
53
mass, foliage mass, total biomass, foliage area, stem surface area, sapwood volume, and total tree volume. High correlation coefficients
(R2) were observed for all variables versus stem diameter, with the highest being for total tree biomass, which ranged from 0.981 for
Oxdendrum arboreum to 0.999 for Quercus coccinea. Foliage area had the lowest R2 values, ranging from 0.555 for Quercus alba to
0.962 for Betula lenta. When all species were combined, correlation coefficients ranged from 0.822 for foliage area to 0.986 for total
wood mass, total tree biomass, and total tree volume. Species with ring versus diffuse/semiring porous wood anatomy exhibited higher
leaf area with a given cross-sectional sapwood area as well as lower total sapwood volume. Liriodendron tulipifera contained one of the
highest foliar nitrogen concentrations and had consistently low branch, bark, sapwood, and heartwood nitrogen contents. For a tree
diameter of 50 cm, Carya spp. exhibited the highest total nitrogen content whereas Liriodendron tulipifera exhibited the lowest.
224. Maritn, Lara A.; Mulholland, Patrick J.; Webster, Jackson R.; Valett, H. Maurice. 2001. Denitrification potential in
sediments of headwater streams in the southern Appalachian mountains, USA. Journal of the North American Benthological Society.
20(4): 505-519.
We investigated variations in resource availability (NO3-N and labile organic C [LOC]) as determinants of potential denitrification in
stream sediments in the southern Appalachian Mountains, USA. Stream water and sediments were sampled seasonally in 2 streams of
contrasting NO3-N availability, Noland Creek (high NO3-N) and Walker Branch (low NO3-N). Eight additional streams with varying
NO3-N levels were sampled once during summer. Stream sediments were incubated at ambient stream temperatures, and nitrous oxide
accumulation was quantified following acetylene inhibition of nitrous oxide reduction. Denitrification potential was greater in Noland
Creek than Walker Branch. In autumn and spring, NO3-N and LOC amendments indicated that denitrification potential in Walker Branch
sediments was NO3-N limited, whereas temperature had no effect on rates. Denitrification potential in Noland Creek sediments was not
limited by NO3-N or LOC, but was significantly affected by season and temperature. However, no differences in denitrification potential
were detected when Noland Creek seasonal data were adjusted to a common temperature. NO3-N in the 10 surveyed streams ranged
from 10 to 549 µ/L, with the highest NO3-N levels and denitrification rates generally occurring in the higher-elevation streams of Great
Smoky Mountains National Park. Our results suggest that NO3-N availability is the primary factor limiting potential denitrification in
Southern Appalachian streams. Despite the ideal conditions of slurry studies, extrapolation of potential rates to estimate denitrification
loss in the catchment channels indicates that the process is an insignificant N sink (1.7% of stream N export in Walker Branch and 1.5%
of N export in the Noland Divide Watershed).
225. Maxwell, Robert A.; Coleman, David C. 1995. Seasonal dynamics of nematode and microbial biomass in soils of riparian-zone
forests of the southern Appalachians. Soil Biology & Biochemistry. 27(1): 79-84.
In a study of the dynamics of labile forest-floor C and N in riparian zones of the Coweeta hardwood forest floor, we measured microbial
biomass and nematodes (principally microbivores) in the top 10 cm seven times in a 10-month period. Total microbial biomass C ranged
from 680 to 1270 mg g soil-1, and was significantly higher in the fall, under Rhododendron than in the general forest area (tulip poplar
and chestnut oak, co-dominants). Total microbial biomass N ranged from 80 to 220 mg g soil -1, reaching a peak in later summer.
Nematodes averaged 11.3 X 106 m-2, among the highest known for nematodes in terrestrial ecosystems. With nematode microbivores
averaging 5% of microbial biomass C, their effects upon the turnover of this labile microbial pool are considerable.
226. Meginnis, H.G. 1956. Principles of watershed management based on current research. In Watershed Management, Interstate
Commission on the Potomac River Basin: 15-19.
Watershed management is the integrated management of all renewable resources of a drainage basin for maximum water production or
control consistent with other economic uses of the land. Principles of watershed management have been acquired within the 20-year
period since the mid 1930's. Accomplishments of research have shown (1) the function of watershed lands in flood prevention, (2) the
deterioration of watersheds with some land management practices after forests are cut, and (3) the ability to manipulate water yields by
forest cutting.
227. Messier, Michael. 2003. Biodiversity-productivity relationships of tree species on the Highlands Plateau. In: Land use change
and implications for biodiversity on the Highlands Plateau; 2003 December 12; Highlands, NC; Highlands, NC: Highlands Biological
Station: 5-29.
The southern Appalachians and the Highlands Plateau in particular are unique in that they provide an environment in which biota from
both the north and the south converge, resulting in communities that are exceptionally rich in species (Zahner 1992). Understanding the
relationships between species diversity (an index of community diversity that takes into account both the number of different species and
the relative abundance of species) and ecosystem attributes, such as productivity and stability, can lend insight to ecosystem function
and, in turn, help to protect the natural environment more effectively (Begon et al. 1990). The purpose of this study is to determine the
nature of the relationships between productivity and species diversity in forest ecosystems of the southern Appalachian Mountains and
their implications for the Highlands Plateau. The role of productivity in ecosystems and its relationship with species diversity is under
rigorous study because productivity is one of several factors that contribute to species composition and function in plant communities
(Begon et al. 1990).
54
228. Meyer, J.L. 1994. The microbial loop in flowing waters. Microbial Ecology. 28: 195-199.
The microbial loop in flowing waters is dependent on allochthonous sources of carbon, which vary in quality. The proportion of
dissolved organic carbon (DOC) that can be degraded ranges from <1 to over 50%, and the bioavailability of DOC (micrograms bacterial
biomass produced per milligram DOC present) ranges over two orders of magnitude. Bioavailability of DOC is predictable from the ratio
of H/C and O/C of the DOC, but further work is needed to develop simple predictors of bioavailability of DOC in a range of
environments. Consumers of bacteria in streams range in size from protists to insect larvae, with highest rates of bacterial consumption
found among the meiofauna and certain filter feeders and grazers. Because there appear to be fewer trophic transfers in lotic microbial
loop, it functions more as a link in flowing waters than it appears to do in the marine plankton.
229. Meyer, Judy L. 1997. Stream health: incorporating the human dimension to advance stream ecology. Journal of the North
American Benthological Society. 16(2): 439-447.
A healthy stream is an ecosystem that is sustainable and resilient, maintaining its ecological structure and function over time while
continuing to meet societal needs and expectations. The concept described in this paper explicitly incorporates both ecological integrity
(maintaining structure and function) and human values (what society values in the ecosystem). Stream ecologists who want their
research to contribute to improving conditions in flowing waters require concepts like stream health, which will stimulate research in
directions that will be more effective in restoring and preserving the unique organisms and ecosystems they study. Determining what is a
healthy stream requires integration of stream ecology with disciplines such as economics and political science; because a concept of
stream health must take into account the human attitudes and social institutions that are a part of the stream's societal watershed. New
and fruitful directions for stream research lie in developing operational measures of stream health, which include the human dimension
and move beyond identifying symptoms of ecological stress, and in elucidating the ecological processes and human actions that maintain
stream health.
230. Meyer, Judy L. 1999. Conserving ecosystem function. In: Pickett, S.T.A.; Ostfeld, R.S.; Shachak, M.; Likens, G.E., eds. The
Ecological basis of conservation heterogeneity, ecosystems, and biodiversity. Millbrook, New York. NY: 136-145. Chapter 10.
This paper presents seven principles from ecosystem science that serve as a foundation for ecosystem conservation. A focus is placed on
ecosystem function and how principles have been or could be used to design and guide conservation efforts.
231. Meyer, Judy L.; Swank, Wayne T. 1996. Ecosystem management challenges ecologists. Ecological Applications. 6(3): 738740.
This essay identifies and discusses challenges presented to ecologists engaged in ecosystem management of natural resources. The Wine
Spring Creek Ecosystem Management project in western North Carolina provides an example that illustrates the research opportunities
and role of ecologists in working with managers and other partners in the development, application, and interpretation of ecological
principals in a management context.
232. Meyer, J.L.; Wallace, J.B. 2001. Lost linkages and lotic ecology: rediscovering small streams. In: Press, Malcolm C.; Huntly,
Nancy J.; Levin, Simon, eds. The 41 st. symposium of the British ecological society jointly sponsored by the Ecological Society of
America. 2000 10-13, April; Orlando, FL. Blackwell Science. 295-317.
The goal of these proceedings is to discuss the achievements of the past and the challenges facing us tomorrow. To explore this topic we
will briefly examine the concepts that have shaped ecological research in flowing waters over the past quarter century and the
opportunities for future advances in the field. We consider this time period because a seminal paper in stream ecology was published by
Noel Nynes in 1975. The paper’s title, ‘The stream and its valley’, conveys its message that organisms and processes in a stream
ecosystem are shaped by the surrounding landscape. The linkage between a stream and its catchment was one of the earliest concepts in
stream ecology (e.g. Ross 1963) and continues to engage stream ecologists today (e.g. Roth et al. 1996). Advances in stream ecology
over the past quarter century have occurred as ecologists explored the linkages that shape lotic ecosystems. Our conceptual models of
flowing water ecosystems incorporate longitudinal (e.g. Vannote et al. 1980; Minshall et al. 1985), lateral (e.g. Junk et al. 1989) and
subsurface (e.g. Boulton et al. 1998; Jones & Mulholland 2000) connections. The tragedy is that while ecologists have been carefully
documenting the importance of these linkages, human society has been severing them by building dams and levees, cutting riparian
forests, removing woody debris, mining groundwater, altering channel morphology and stream hydrology, and filling or piping entire
channels. When these destructive practices are combined with anthropogenic alterations in water quality and spread of exotic species, it
is not surprising that freshwater taxa are far more threatened than terrestrial taxa in North America (Ricciardi & Rasmussen 1999).
Inadequate recognition of flowing waters are human-dominated ecosystems was a gap in much of 20th century stream research. Hence, a
challenge for ecology in the future lies in developing a predictive understanding of the connections between ecological conditions in
flowing waters and the human attitudes, institutions and policies that dominate these ecosystems (Naiman et al. 1995). Linking
ecological, ethical, economic, and legal analyses will be essential to sustain the integrity of lotic ecosystems (Meyer 1997). We explore
these ideas here by focusing on small streams. The literature is much richer than can be presented in a short paper, so the citations are
intended as introductions to an extensive body of research.
55
233. Meyer, Judy L.; Wallace, J. Bruce; Eggert, Sue L. 1998. Leaf litter as a source of dissolved organic carbon in streams.
Ecosystems. 1: 240-249.
Dissolved organic carbon (DOC) is an abundant form of organic matter in stream ecosystems. Most research has focused on the
watershed as the source of DOC in streams, but DOC also comes from leaching of organic matter stored in the stream channel. We used
a whole-ecosystem experimental approach to assess the significance of leaching of organic matter in the channel as a source of DOC in a
headwater stream. Inputs of leaf litter were excluded from a forested Appalachian headwater stream for 3 years. Stream-water
concentration, export, and instream generation of DOC were reduced in the litter-excluded stream as compared with a nearby untreated
reference stream. The proportion of high molecular weight (HMW) DOC (more than 10,000 daltons) in stream water was not altered by
litter exclusion. Mean DOC concentration in stream water was directly related to benthic leaf-litter standing stock. Instream generation
of DOC from leaf litter stored in the stream channel contributes approximately 30% of daily DOC exports in this forested headwater
stream. This source of DOC is greatest during autumn and winter and least during spring and summer. It is higher during increasing
discharge than during base flow. We conclude that elimination of litter inputs from a forested headwater stream has altered the
biogeochemistry of DOC in this ecosystem.
234. Mitchell, Chris E.; Turner, Monica G.; Pearson, Scott M. 2002. Effects of historical land use and forest patch size on
myrmecochores and ant communities. Ecological Applications. 12(5): 1364-1377.
We studied the effects of patch size and historical land use on woodland ants and myrmecochores (plant species that have their diaspores
dispersed by ants) in mesic forests of the southern Appalachian Highlands. Our purpose was to examine a potential mechanism, the
presence and diversity of seed-dispersing ants, that might explain the reduced abundance and diversity of myrmecochores in small forest
patches with high intensities of past land use. Small patches (<25 ha) of forest harbored a greater abundance and diversity of
myrmecochorous ants, but a lower abundance and species richness of myrmecochores than large patches (>200 ha) with minimal past
land use. Overall, sites with greater myrmecochore species richness and abundance had less diverse ant communities and a lower
abundance of ants. However, ant species composition varied with patch size. Large patches with low historical land-use intensity were
dominated by one ant species, Aphaenogaster fulva, whereas small patches supported higher numbers of Aphaenogaster rudis and two
Camponotus species. The abundances of immature myrmecochores were more strongly related to land-use history, forest patch size, and
the abundance of mature conspecifics than to ant variables. An absence of seed-dispersing ants cannot explain the reduced numbers of
myrmecochores in small patches with high past land use because seed dispersal by ants still appears to be available in those patches.
Land-use legacies or fragmentation effects may be overriding any advantages offered by the increased diversity and abundance of ants at
those sites.
235. Mitchell, Katherine, A.; Bolstad, Paul V.; Vose, James M. 1999. Interspecific and environmentally induced variation in foliar
dark respiration among eighteen southeastern deciduous tree species. Tree Physiology. 19: 861-870.
We measured variations in leaf dark respiration rate (Rd) and leaf nitrogen (N) across species, canopy light environment, and elevation
for 18 co-occurring deciduous hardwood species in the southern Appalachian mountains of western North Carolina. Our overall
objective was to estimate leaf respiration rates under typical conditions and to determine how they varied within and among species.
Mean dark respiration rate at 20 °C (Rd, mass, µmol CO2 (kg leaf dry mass)-1s-1) for all 18 species was 7.31µmol kg 1s-1. Mean Rd, mass of
individual species varied from 5.17-µmol -1s-1 for Quercus coccinea Muenchh. To 8.25-µmol kg 1s-1 for Liriodendron tulipifera L. Dark,
respiration rate varied by leaf canopy position and was higher in leaves collected from highlight environments. When expressed on an
area basis, dark respiration rate (Rd, area, µmol CO2 (kg leaf dry area)-1s-1) showed a strong linear relationship with the predictor variables
leaf nitrogen (N area, g N (m leaf area)-2) and leaf structure (LMA, g leaf dry mass (m leaf area) –2) (r2= 0.62). This covariance was
largely a result of changes in leaf structure with canopy position; smaller thicker leaves occur at upper canopy positions in highlight
environments. Mass-based expression of leaf nitrogen and dark respiration rate showed that nitrogen concentration (N mass, mg N (g leaf
dry mass) –1) was only moderately predictive of variation in Rd, mass for all leaves pooled (r2 = 0.11), within species, or among species.
We found distinct elevational trends, with both Rd, mass and N mass higher in trees originating from high-elevation, cooler growth
environments. Consideration of interspecies differences, vertical gradients in canopy light environment, and elevation, may improve our
ability to scale leaf respiration to the canopy in forest process models.
236. Mulholland, P.J.; Fellows, C.S.; Tank, J.L.; Grimm, N.B.; Webster, J.R.; Hamilton, S.K.; Marti, E.; Ashkenas, L.;
Bowden, W.B.; Dodds, W.K.; McDowell, W.H.; Paul, M.J.; Peterson, B.J. 2001. Inter-biome comparison of factors controlling
stream metabolism. Freshwater Biology. 46: 1503-1517.
We studied whole-ecosystem metabolism in eight streams from several biomes in North America to identify controls on the rate of
stream metabolism over a large geographic range. The streams studied had climates ranging from tropical to cool-temperate and from
humid to arid and were all relatively uninfluenced by human disturbances. Rates of gross primary production (GPP), ecosystem
respiration (R) and net ecosystem production (NEP) were determined using the open-system, two-station diurnal oxygen change method.
Three general patterns in metabolism were evident among streams: (1) relatively high GPP with positive NEP (i.e. net oxygen
production) in early afternoon, (2) moderate primary production with a distinct peak in GPP during daylight but negative NEP at all
times and (3) little or no evidence of GPP during daylight and a relatively constant and negative NEP over the entire day. Gross primary
production was most strongly correlated with photosynthetically active radiation (PAR). A multiple regression model that included log
56
PAR and stream water soluble reactive phosphorus (SRP) concentration explained 90% of the variation in log GPP. Ecosystem
respiration was significantly correlated with SRP concentration and size of the transient storage zone and, together, these factors
explained 73% of the variation in R. The rate of R was poorly correlated with the rate of GPP. Net ecosystem production was
significantly correlated only with PAR, with 53% of the variation in log NEP explained by log PAR. Only Sycamore Creek, a desert
stream in Arizona had positive NEP (GPP: R>1), supporting the idea that streams are generally net sinks rather than net sources of
organic matter. Our results suggest that light, phosphorus concentration, and channel hydraulics are important controls on the rate of
ecosystem metabolism in streams over very extensive geographic areas.
237. Mulholland, P.J.; Tank, J.L.; Webster, J.R.; Bowden, W.B.; Dodds, W.K.; Gregory, S.V.; Grimm, N.B.; Hamilton, S.K.;
Johnson, S.L.; Marti, E.; McDowell, W.H.; Merriam, J.L.; Meyer, J.L.; Peterson, B.J.; Valett, H.M.; Wollheim, W.M. 2002. Can
uptake length in streams be determined by nutrient addition experiments? Results from an interbiome comparison study. Journal of the
North American Benthological Society. 21(4): 544-560.
Nutrient uptake length is an important parameter for quantifying nutrient cycling in streams. Although nutrient tracer additions are the
preferred method for measuring uptake length under ambient nutrient concentrations, short-term nutrient addition experiments have more
frequently been used to estimate uptake length in streams. Theoretical analysis of the relationship between uptake length determined by
nutrient addition experiments (Sw') and uptake length determined by tracer additions (Sw) predicted that Sw' should be consistently longer
than Sw, and that the overestimate of uptake length by Sw' should be related to the level of nutrient addition above ambient concentrations
and the degree of nutrient limitation. To test these predictions, we used data from an interbiome study of NH4+ uptake length in which
15NH + tracer and short-term NH + addition experiments were performed in 10 streams using a uniform experimental approach. The
4
4
experimental results largely confirmed the theoretical predictions: S- w´ was consistently longer than Sw and Sw´:Sw ratios were directly
related to the level of NH4+ addition and to indicators of N limitation. The experimentally derived S w':Sw ratios were used with the
theoretical results to infer the N limitation status of each stream. Together, the theoretical and experimental results showed that tracer
experiments should be used whenever possible to determine nutrient uptake length in streams. Nutrient addition experiments may be
useful for comparing uptake lengths between different streams or different times in the same stream, however, provided that nutrient
additions are kept as low as possible and of similar magnitude.
238. Mulholland, Patrick J. 1997. Dissolved organic concentration and flux in streams. In: Webster J.R.; Meyer, J.L., eds. Stream
organic matter budgets. Journal of the North American Benthological Society. 16: 122-131.
This chapter is part of a multi-site analysis of organic matter dynamics in streams. Channel slope was the best predictor of DOM
concentration and export, probably because of its relationship with riparian wetlands and hydrologic flowpaths.
239. Mulholland, Patrick J.; Marzolf, Erich R.; Webster, Jackson R.; Hart, Deborah, R.; Hendricks, Susan P. 1997. Evidence
that hyporheic zones increase heterotrophic metabolism and phosphorus uptake in forest streams. Limnology and Oceanography. 42(3)
443-451.
We used nondisruptive, whole-stream methods to measure hydraulic characteristics, ecosystem metabolism, and phosphorus cycling in
the west fork of Walker Branch (WB), Tennessee and in Hugh White Creek (HWC), North Carolina. Although similar in many of their
hydrological and chemical characteristics, transient storage zone volume in HWC was relatively large, whereas transient storage zone
volume in WB was small. Both streams were highly heterotrophic, although respiration rate was ~2.4 times greater in HWC than in WB.
Phosphorus uptake rate was ~2.6 times greater in HWC than in WB, and P uptake length was 5 times longer in WB than HWC. Analysis
of 33P:3H ratio profiles from 33PO4 and 3H20 injection experiments indicated that P uptake within the transient storage zone accounted for
~43% of the total P uptake in HWC but was negligible in WB, explaining, in part, the difference in total P uptake rate between these
streams. The higher rate of P uptake in the surface zone, shorter P uptake length, and larger ratio of P uptake: respiration in HWC
compared with WB suggest that the microbial community in HWC exerts a greater demand for and has a greater affinity for streamwater
P, presumably as a result of a greater supply of labile organic matter and/or lower nutrient levels in HWC.
240. Mulholland, Patrick J.; Tank, Jennifer L.; Sanzone, Diane M.; Wollheim, Wilfred M.; Peterson, Bruce J.; Webster,
Jackson R.; Meyer, Judy L. 2000. Nitrogen cycling in a forest stream determined by a 15N tracer addition. Ecological Monographs.
70(3): 471-493.
Nitrogen uptake and cycling was examined using a six-week tracer addition of 15N-labeled ammonium in early spring in Walker Branch,
a first-order deciduous forest stream in eastern Tennessee. Prior to the 15N addition, standing stocks of N were determined for the major
biomass compartments. During and after the addition 15N was measured in water and in dominant biomass compartments upstream and
at several locations downstream. Residence times of ammonium in stream water (5-6 min) and ammonium uptake lengths (23-27 m)
were short and relatively constant during the addition. Uptake rates of NH 4 were more variable, ranging from 22 to 37 μg N·-2· min.–1
and varying directly with changes in streamwater ammonium concentration (2.7-6.7 μg /L). The highest rates of ammonium uptake per
unit area were by the liverwort Porella pinnata, decomposing leaves, and fine benthic organic matter (FBOM), although epilithon had
the highest N uptake per unit biomass, N. Nitrification rates and nitrate uptake lengths and rates were determined by fitting a
nitrification/nitrate uptake model to the longitudinal profiles of 15N-NO3 flux. Nitrification was an important sink for ammonium in
stream water, accounting for 19% of the total ammonium uptake rate. Nitrate production via coupled regeneration/nitrification of organic
57
N was about on half as large as nitrification of streamwater ammonium. Nitrate uptake lengths were longer and more variable that those
for ammonium, ranging from 101 m to infinity. Nitrate uptake rate varied from 0 to 29 μgm -2.min-1 and was ~1.6 times greater than
assimilatory ammonium uptake rate early in the tracer addition. A six-fold decline in stream gross primary production rate resulting from
a sharp decline in light level with leaf emergence had little effect on ammonium uptake rate but reduced nitrate uptake rate by nearly
70%. At the end of the addition, 64-79% of added 15N was accounted for either in biomass within the 125-m stream reach (33-48%) or as
export of 15N-NH4 (4%), 15N-NO3 (23%), and fine particulate organic matter (4%) from the reach. Much of the 15N not accounted fro
was probably lost downstream as transport of particulate organic N during a storm midway through the experiment or as dissolved
organic N produced with the reach. Turnover rates of a large portion of the 15N taken up by biomass compartments are high (0.04-0.08
per day), although a substantial portion of the 15N in Porella (34%), FBOM (21%), and decomposing wood (17%) at the end of the
addition was retained 75 d later, indicating relatively long-term retention of some N taken up from water. In total, our results showed that
ammonium retention and nitrification rates were high in Walker Branch, and that the downstream loss of N was primarily as nitrate and
was controlled largely by nitrification, assimilatory demand for N, and availability of ammonium to meet that demand. Our results are
consistent with recent 15N tracer experiments in N-deficient forest soils that showed high rates of nitrification and the importance of
nitrate uptake in regulating losses of N. Together, these studies demonstrate the importance of 15N tracer experiments for improving our
understanding of the complex processes controlling N cycling and loss in ecosystem.
241. Mulholland, Patrick J.; Tank, Jennifer L.; Sanzone, Diane M.; Wollheim, Wilfred M.; Peterson, Bruce J.; Webster,
Jackson R.; Meyer, Judy L. 2000. Food resources of stream macroinvertebrates determined by natural-abundance stable C and N
isotopes and a 15N tracer addition. Journal North America Benthological Society. 19(1): 145-157.
Trophic relationships were examined using natural-abundance 13C and 15N analyses and a 15N-tracer addition experiment in Walker
Branch, a 1st-order forested stream in eastern Tennessee. In the 15N-tracer addition experiment, we added 15N: 14N ratios in different taxa
and biomass compartments over distance and time. Samples collected from a station upstream from the 15N addition provided data on
natural-abundance 13C: 14N ratios. The natural-abundance 15N analysis proved to be of limited value in identifying food resources of
macroinvertebrates because 15N values were not greatly different among food resources, In general, the natural-abundance stable isotope
approach was most useful for determining whether epilithon or detritus were important food resources for organisms that may use both
(e.g., the snail Elimia clavaeformis), and to provide corroborative evidence of food resources of taxa for which the 15 N tracer results
were not definitive. The 15N tracer results showed that the mayflies Stenonema supp. and Baetis spp. assimilated primarily epilithon,
although Baetis spp. assimilated primarily epilithon, although Baetis appeared to assimilate a portion of the epilithon (e.g., algal cells)
with more rapid N turnover than the bulk pool sampled. Although Elimia did not reach isotopic equilibrium during the tracer experiment,
application of a N-turnover model to the field data suggested that it assimilated a combination of epilithon and detritus. The amphipod
Gammarus minus appeared to depend mostly on fine benthic organic matter (FBOM), and the coleopteran Anchytarsus bicolor on
epixylon. The caddisfly Diplectroma modesta appeared to assimilate primarily a fast N-turnover portion of the FBOM pool, and
Simuliidae a fast N-turnover component of the suspended particulate organic matter pool rather than the bulk pool sampled. Together,
the natural-abundance stable C and N isotope analyses and the experimental 15N tracer approach proved to be very useful tools for
identifying food resources in this stream ecosystem.
242. Naiman Robert J.; Turner, Monica G. 2000. A future perspective on North America’s freshwater ecosystems. Ecological
Applications. 10(4): 958-970.
Fresh waters are central to society and to the environment. Nevertheless, ongoing and projected changes in the distribution, abundance,
and quality of water resources and freshwater ecosystems represent a serious threat to the integrity of the environment as well as the
vitality of human cultures. Nearly every country in the world experiences regular water shortages, agriculture uses most of the world’s
available fresh water, and most illnesses in developing countries result from waterborne parasites and pathogens. Unfortunately, often
hidden in these and other depressing statistics are the needs of the environment for adequate water to maintain vibrant ecosystems.
Understanding the abilities and limits of freshwater ecosystems to respond to human-generated pressures is becoming a central issue for
cultures and a challenge for science. This article explores trends in alterations for freshwater ecosystems, discusses the ecological
consequences of biophysical alterations expected to occur in the next 20-30 years, and identifies some of the major scientific challenges
and opportunities to effectively address the changes. Topics include altered hydrological regimes, biogeochemical cycles, altered land
use, riparian management, life history strategies, and relations between climate change and water resource management.
243. Naiman Robert J.; Bisson, Peter A.; Lee, Robert G.; Turner, Monica G. 1997. Approaches to management at the watershed
scale. In: Kohm, Kathryn A.; Franklin, Jerry F., eds. Creating forestry for the 21st century. The Science of Ecosystem Management.
Island Press: Springer-Verlag: 239-253.
Freshwater and freshwater ecosystems lie at the heart of the challenge of ecosystem management (Naiman 1992, Lee 1993, Naiman et al.
1995a, 1995b). Because they integrate natural resource and socioeconomic systems, freshwater issues embody the complexity that will
characterize natural resource management as we move into the 21 st. century. Changes in human demography, resource consumption
cultural values, institutional processes, technological applications, ad information all contribute to that complexity. If we are to achieve
long-term social stability as well as ecological vitality, we must understand the abilities and limits of freshwater ecosystems to respond
to human-generated pressures. Yet, even though human actions and cultural values drive environmental issues, few holistic approaches
for the watershed management offer effective resolution.
58
In the current debate over the scope of ecosystem to respond to human-generated pressures. (Grumbin 1994, Montgomery et. al. 1995), it
is widely recognized that there are significant technical and cultural constraints to effective implementation. These constraints are related
to such issues as identifying appropriate spatial and temporal scales, monitoring and assessment, developing an adaptive management
process, and developing cultural values and philosophies that allow ecosystem management to be successful (Levin 1993, Grumbine
1994). Nonetheless, the ability of rapidly increasing human population to dramatically impact local, regional, and global ecosystems
makes it essential to incorporate an ecological perspective into watershed management if we are to leave a healthy resource base for
future generations.
The first part of this chapter suggests several features that are fundamental to contemporary watershed management. The second part
then presents several practical approaches for implementing effective watershed management programs.
244. Naiman, Robert J.; Bisson, Peter A.; Lee, Robert G.; Turner, Monica G. 1998. Watershed management. In: Naiman, Robert
J.; Bilby, Robert E., eds. River ecology and management. Lessons from the Pacific Coastal Ecoregion. New York, NY: Springer-Verlag:
642-661.
Management at the watershed scale is a major challenge facing present and future generations. Watershed management requires
integrating scientific knowledge of ecological relationships within a complex framework of cultural values and traditions to provide
socioenvironmental integrity can operate for the long term and over large spatial scales-especially within hydrologically identifiable
boundaries.
Development of a watershed management perspective incorporates variability in time and space, takes a holistic approach toward the
persistence of ecological features, treats human cultures and institutions as inherent features, and addresses system connectivity and
uncertainty.
Several approaches are presented for implementing watershed management that relate to public stewardship (monitoring and education),
accepting and dealing with risk, addressing uncertainty, formulating a shared vision, quantitatively analyzing socioenvironmental
conditions, and structuring institutional organization.
Although there is, no set methodology for achieving effective watershed management fundamental principles related to cooperative
balance, fairness, integration, trust, responsibility, communication, and adaptability are essential for guiding the process.
245. Neatrour, Matthew A.; Webster, Jackson R.; Benfield, Ernest F. 2004. The role of floods in particulate organic matter
dynamics of a southern Appalachian river-floodplain ecosystem. Journal of the North American Benthological Soicety. 23(2): 198-213.
We investigated the effect of a flood on particulate organic matter (POM) dynamics in the floodplain and active channel of the Little
Tennessee River in western North Carolina. We measured litterfall, leaf breakdown, and floodplain litter (before and after the flood) at
12 sites. Annual litterfall (256–562 g m22 y21) was typical of a temperate deciduous forest but lower than lowland floodplain forests in
the eastern US. Leaf breakdown rates of 4 tree species (Acer rubrum, Carpinus caroliniana, Juglans nigra, and Platanus occidentalis)
ranged from 0.001 to 0.010/d. We separated the 12 sites into 2 groups (inundated and non-inundated) based on the degree of flooding
after a flood on 8 January 1998 and determined POM exchange between the active channel and floodplain. Significant transport of
leaves from the floodplain to the river occurred at inundated sites, but transport of herbaceous or woody material did not occur. The
flood increased leaf breakdown rates of all 4 tree species. Our measurements of litterfall, leaf breakdown, and floodplain litter standing
crop suggest that leaves entrained from the floodplain of Little Tennessee River during floods are a source of POM to the active channel.
However, flood input of leaves to the river were a small source of POM compared to direct leaffall.
246. Nihlgard, Bengt J.; Swank, Wayne T.; Mitchell, Myron J. 1994. Biological processes and catchment studies. In: Moldan, B.;
Cerny, J., eds. Biogeochemistry of small catchments: a tool for environmental research. Scientific Committee on Problems of the
Environment (SCOPE) 51. Chichester, U.K.: John Wiley & Sons Ltd.: 133-161.
Catchments are influenced by physical, chemical, and biological processes in many different ways. This evaluation of biological
processes, which are studied in small catchments, is restricted to biological variables that might influence the groundwater and surface
water of the catchment with implicating effects on the whole ecosystem. Biological reactions taking part within populations or organisms
in a shorter time perspective might be processes difficult to evaluate on an ecosystem basis. Very few catchment studies have focused on
such biological processes.
247. Nilsen, E.T.; Clinton, B.D., Lei, T.T.; Miller, O.K.; Semones, S.W.; Walker, J.F. 2001. Does rhododendron maximum L.
(Ericaceae) reduce the availability of resources above and belowground for canopy tree seedlings? American Midland Naturalist. 145:
325-343.
Subcanopy shrubs and perennial herbs inhibit recruitment of canopy trees in forests around the world. Although this phenomenon is
widespread, and can have significant effects on community dynamics, the mechanisms of inhibition are not well understood. In the
southern Appalachian region. Rhododendron maximum inhibits the recruitment of canopy tree in forests of northern red oak (Quercus
rubra). We have shown, in previous research, that processes occurring before canopy tree seed germination are not responsible for this
inhibition. Therefore, post-germination processes, such as competition for resources are most important. In this study we show that the
presence of a thicket of R. maximum in the understory reduced the availability of light by 80%, the frequency and duration of sunflecks
by 96%, the availability of water by 20% and the availability of several soil nutrients (particularly cations) by variable amounts.
59
Moreover, the survival of Q. rubra seedlings in the understory over 3 y was significantly reduced (by about 40%) in the presence of a R.
maximum thicket compared with forest without a thicket. Seedling survival was positively associated with light availability, but the
slope and intercept of that relationship was different in forest with or without R. maximum. Therefore, belowground processes are
involved in reduced seedling survival under the R. maximum thicket. The resources most associated with survival of Q. rubra seedlings
were water and light. Although many soil nutrients were significantly lower in forest with R. maximum than in forest with R. maximum,
no individual nutrient was a significant covariate with Q. rubra survivorship. Our data indicate that competition for resources both
above-and belowground is an important mechanism for inhibition of canopy tree recruitment by R. maximum. Light is important to
seedling survival, but is not the only important factor. Water availability and the ability to accumulate soil nutrients are equally or more
important than light to survival of canopy tree seedlings in the presence of a subcanopy thicket of R. maximum.
248. Nilsen, Erik T.; Walker, John F.; Miller, Orson, K.; Semones, Shawn W.; Lei, Thomas T.; Clinton, Barton, D. 1999.
Inhibition of seedling survival under Rhododendron maximum (Ericaceae): could Allelopathy be a cause? American Journal of Botany.
86(11): 1597-1605.
In the southern Appalachian mountains, a subcanopy species, Rhododendron maximum, inhibits the establishment and survival of
canopy tree seedlings. One of the mechanisms by which seedlings could be inhibited is an allelopathic effect of decomposing litter or
leachate from the canopy of R. maximum (R.M.) on seed germination, root elongation, or mycorrhizal colonization. The potential for
allelopathy by R.m. was tested with two bioassay species (lettuce and cress), with seeds from four native tree species, and with three
ectomycorrhizal fungi. Inhibitory influences of throughfall, fresh litter, and decomposed litter (organic layer) from forest with R.m.
(+R.m. sites) were compared to similar extractions made from forest without R.m. (-R.m. sites). Throughfall and leachates of the organic
layer from both +R.m. and -R.m. sites stimulated germination of bioassay species above that of the distilled water control, to a similar
extent. There was an inhibitory effect of leachates of litter from +R.m. sites on seed germination and root elongation rate of both
bioassay species compared with that of litter from -R.m. sites. Native tree seed stratified in forest floor material from both forest types
had a slightly higher seed germination rate compared with the control. A 2-yr study of seed germination and seedling mortality of two
tree species. Quercus rubra and Prunus serotina, in field plots showed no significant influence of litter or organic layer from either
forest type. Incorporating R.m. leaf material into the growth medium in vitro depressed growth of one ectomycorrhizal species but did
not affect two other species. Leaf material from R.m. In conclusion, R.m. litter can have an allelopathic effect on seed germination and
root elongation of bioassay species, as will as some ectomycorrhizal species. However, this allelopathic affect is not manifest in field
sites and is not likely to be an important cause for the inhibition of seedling survival within thickets of R.m.
249. Olson, Matthew S. 1997. Bayesian procedures for discriminating among hypotheses with discrete distributions: Inheritance in
the Tetraploid Astilbe biternata. Genetics Society of America. 147: 1933-1942.
Discrimination between disomic and tetrasomic inheritance aids in determining whether tetraploids originated by allotetraploidy or
autotetraploidy, respectively. Past assessments of inheritance in tetraploids have used analyses whereby each inheritance hypothesis is
tested independently. I present a Bayesian analysis that is appropriate for discriminating among several inheritance hypotheses and can
be used in any case where hypotheses are defined by discrete distributions. The Bayesian approach incorporates prior knowledge of the
probability of occurrence of disomic and tetrasomic hypotheses so that the results of the analysis are not biased by the fact that there is a
single tetrasomic hypotheses and multiple disomic hypotheses. This analysis is used to interpret data from crosses in the tetraploid
Astilbe biternata, a herbaceous plant native to the southern Appalachians. The progeny ratios from all crosses favored the hypothesis of
disomic inheritance at both the PGM and slow-PGI loci. These results support earlier cytogenetic evidence for the allotetraploid origin of
Astilbe biternata.
250. Pearson, Scott M. 2002. Interpreting landscape patterns from organism-based perspectives. In: Gergel, Sarah E.; Turner, Monica
G., eds. Learning landscape ecology a practical guide to concepts and techniques. New York, NY. Springer Verlag: 187-198.
For effective conservation management, maps are needed that reflect the resource needs of ecosystems and non-human species. This
laboratory exercise is designed to introduce students to important concepts related to producing and interpreting such maps. The exercise
has three major components: (a) the potential limitations on habitat mapping due to the resolution of spatial data, (b) constructing habitat
maps for five species, and (c) combining land cover and topographic position to create habitat maps for two additional species. Students
also employ simple metrics of spatial pattern to compare the abundance and fragmentation of different species. Electronic copies of the
habitat maps are available on a CD-ROM included with the book.
251. Pearson, Scott M. 2002. Landscape context. In: Gergel, Sarah E.; Turner, Monica G. eds. Learning landscape ecology a practical
guide to concepts and techniques. New York, NY, Springer Verlag: 199-207.
Ecological processes at a given site are the result of both local dynamics and processes acting at the broader scale of the surrounding
landscape. This laboratory exercise is meant to illustrate the importance of landscape context on the community dynamics of habitat
patches, an important issue for basic ecological research and for conservation. The objectives of the exercise are to: (a) learn to
quantitatively describe the ecological neighborhood around a specific study site, (b) conduct statistical tests to determine if
characteristics of the landscape neighborhood are correlated with local community composition, and (c) consider why the effects of
landscape context may vary among species. The exercise uses data describing community composition of herbaceous species found in
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Southern Appalachian temperate forests. Data files in spreadsheet form and maps of the study landscape are available on a CD-ROM
included with the book.
252. Pearson, Scott M.; Gardner, Robert H. 1997. Neutral models: useful tools for understanding landscape patterns. In: Bissonette,
John A., ed. Wildlife and landscape ecology: Effects of pattern and scale. New York, NY: Springer: 215-230.
A neutral model is a minimum set of rules required to generate pattern in the absence of a particular process. Neutral models are useful
in landscape ecology. The purpose of this chapter is to demonstrate their utility in this field of study by discussing how neutral models
(1) assist the investigator in understanding patterns in spatial data and (2) are useful for generating maps for quantifying the effort of
landscape pattern on ecological processes. Percolation theory is used to illustrate critical thresholds in habitat
fragmentation/connectivity. Methods for generating hierarchical and fractal maps of "neutral landscapes" are explained. Studies of lake
sediment contamination and population dynamics of forest plants are summarized to illustrate the role of maps generated by neutral
models in landscape ecology research.
253. Pearson, Scott M.; Smith, Alan B.; Turner, Monica G. 1998. Forest patch size, land use, and mesic forest herbs in the French
Broad River Basin, North Carolina. Castanea. 63(3): 382-395.
The effect of forest fragmentation on cove-forest herbs was studied in the Southern Blue Ridge Province. Patches of mesic forests were
sampled with 4 ha study plots. The coverage and density of herb species were greater in large patches (>200 ha) than in small patches
(<10 ha). Several ant-dispersed species, such as Disporum maculatum and Uvularia grandiflora, were more likely to be absent from
small patches than from large patches. Wind-dispersed species, such as ferns and composites, were not affected by patch size and
isolation. Small patches had reduced amounts of organic matter in the soil, suggesting that small patches have experienced more
disturbance than large patches. Otherwise, there were no other differences in soil characteristics between patch sizes. Mechanisms
hypothesized to have affected these populations include (a) disruption of population dynamics due to habitat fragmentation, (b) habitat
degradation, and (c) anthropogenic disturbance via land use. Disturbances may have affected herb populations directly by increasing
mortality rates and by degrading habitat. These habitat changes were confounded by the small size and isolation of small forest patches.
254. Pearson, Scott, M.; Turner, Monica G.; Drake, Jason B. 1999. Landscape change and habitat availability in the southern
Appalachian Highlands and Olympic Peninsula. Ecological Applications. 9(4): 1288-1304.
Methods for predicting the ecological impacts of land use change on biodiversity and ecosystem function are needed to guide land
planning and resource management decisions. This study explores the consequences of alternative scenarios of land cover change on the
abundance and arrangement of potential habitat for a suite of species in the Little Tennessee River Basin (LTRB) in the Southern
Appalachian Highlands and the Hoh River Basin (HORB) on the Olympic Peninsula. We addressed two questions: (1) How does land
ownership affect the availability of suitable habitat for a variety of species in changing landscapes (and how do restrictions on forest
harvest hen change habitat availability)? (2) Are species differentially affected by land cover changes that vary among landowners?
Scenarios of land cover change were projected by using a spatially explicit model in which the probability of land being converted from
one cover type to another was conditional upon social, economic, and ecological factors. Potential habitat was defined for each species
based on resource needs related to land cover and topography and was mapped at each time step. Spatial pattern of potential suitable
habitat for each species was analyzed by computing area, number of patches, mean patch size, and area of the largest patch of suitable
habitat. Simulations extended for 100 yr with a 5-yr time step. The different scenarios, based on historical periods and management
options regulating forest loss produced qualitatively different landscapes. Restrictions on forest harvest produced more, better-connected
habitat for forest species. However, habitat changes for species were only partially predicted by changes in land cover types. Fore
example, a 5-10% decrease in the amount of grassy or brushy cover in the HORB resulted in a 10-20% reduction in habitat for
honeysuckle. When responses of all species were considered collectively, there were effects of both private and public ownerships in the
LTRB but no interaction between the two ownership types. In the HORB, variation in the rates of land cover change for public lands had
the greatest effect on species habitats. Our results suggest that both landscape-level approaches, which provide a means to quantify and
monitor broad-scale changes related to biodiversity and ecosystem processes, and species-level approaches, which provide an
appropriate context for interpreting the significance of landscape-level changes, are useful for effective conservation.
255. Pearson, Scott M.; Turner, Monica G.; Urban, Dean L. 1999. Effective exercises in teaching landscape ecology. In: Klopatek,
Jeffrey M.; Gardner, Robert H., eds. Landscape ecological analysis: Issues and applications. New York, NY. Springer Verlag. 335-368.
Chapter 15.
The development of landscape ecology and its many applications to land management created a need for courses that address both the
conceptual and practical sides of the discipline. Graduate seminars and full-fledged courses in landscape ecology are now featured at
many colleges and universities; undergraduate ecology courses may include an introduction to principles of landscape ecology. Because
landscape ecology involves the study of spatially explicit ecological patterns and processes along with much larger regions than
ecologists have typically studied, landscape ecologists often employ a variety of new quantitative analysis techniques in their work. In
particular, metrics are used to quantify spatial patterns, and the importance of spatial heterogeneity for ecological processes is evaluated.
Modeling also plays an important role in landscape ecology because it is logistically impossible to conduct truly replicated experiments
across entire landscapes. Students of landscape ecology, even at the undergraduate level, need some familiarity with the tools of the
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discipline to gain confidence in the practice of landscape ecology and to develop a critical understanding of the strengths and weaknesses
of these techniques.
256. Peterson, Bruce J.; Wollheim, Wilfred M.; Mulholland, Patrick J.; Webster, Jackson R.; Meyer, Judy L.; Tank, Jennifer
L.; Marti, Eugenia; Bowden, William B.; Valett, H. Maurice; Hershey, Anne E.; McDowell, William H.; Dobbs, Walter K.;
Hamilton, Stephen K.; Gregory, Stanley; Morrall, Donna D. 2001. Control of nitrogen export from watersheds by headwater streams.
Science. 292: 86-90.
A comparative 15N-tracer study of nitrogen dynamics in headwater streams from biomes throughout North America demonstrates that
streams exert control over nutrient exports to rivers, lakes, and estuaries. The most rapid uptake and transformation of inorganic nitrogen
occurred in the smallest streams. Ammonium entering these streams was removed from the water within a few tens to hundreds of
meters. Nitrate was also removed from stream water but traveled a distance 5 to 10 times as long, on average, as ammonium. Despite
low ammonium concentration in stream water, nitrification rates were high, indicating that small streams are potentially important
sources of atmospheric nitrous oxide. During seasons of high biological activity, the reaches of headwater streams typically export
downstream less than half of the input of dissolved inorganic nitrogen from their watersheds.
257. Petty, J. Todd; Grossman, Gary D. 1996. Patch selection by mottled sculpin (Pisces: cottidae) in a southern Appalachian
stream. Freshwater Biology. 35: 261-276.
We examined the effects of prey abundance on patch selection by a benthic fish, the mottled sculpin, in a fourth order, southern
Appalachian stream. This habitat is a mosaic of small (i.e. <0.5m2), relatively discrete patches. Patches were characterized by physical
habitat variables, detritus, and macroinvertebrate abundance. Patches selected by sculpin contained significantly higher
macroinvertebrate abundances than locally available patches in five out of six seasonal samples. Sculpin also occupied patches with
significantly higher amounts of CPOM in three out of five seasonal samples. Patches utilized by sculpin, however, could not be
consistently differentiated from locally available patches on the basis of physical variables. Results suggest that sculpin are able to assess
patch quality and select patches that potentially maximize energy gain. This behavior may produce an increase in individual fitness.
258. Petty, J.T.; Grossman, G. D. 2000. The effects of an underwater fish observation technique on stream macroinvertebrates at two
spatial scales. Ecology of Freshwater Fish. 9: 145-152.
We examined the effects of snorkeling, a commonly used fish observation technique, on the distribution and abundance of benthic
macroinvertebrates at both the reach (i.e. 10 m) and patch scale (i.e., < 1 m) within a southern Appalachian stream (North Carolina,
USA). At the reach scale, we quantified increases in macroinvertebrate drift rates associated with snorkeling and used these values to
calculate the percentage of the macrobenthos that drifted out of snorkeled reaches. We also used a simple decay model of
macroinvertebrate drift to quantify patch scale effects of snorkeling. The model incorporated size specific macroinvertebrate settling
rates to estimate the total number of benthic macroinvertebrates that enter the drift in response to snorkeling disturbance. We found that
snorkeling consistently produced significant increases in the number of drifting macroinvertebrates. Nevertheless, these increases
comprised a very small percentage (<1%) of the total number of organisms in the benthos, suggesting that snorkeling probably did not
strongly affect macroinvertebrate assemblages at either the reach or patch scale. However, our analyses also indicated that snorkeling
had a disproportionate response to snorkeling) relative to other macroinvertebrate taxa. Consequently, the micro distribution of early
instar mayflies may have been altered within snorkeled reaches. We conclude that snorkeling related disturbance to the benthos should
have minimal effect on the behavior and distribution of most stream fishes at either the reach or patch scale. However, because
snorkeling may influence the behavior of fishes that depend on early instar mayflies as a primary food source.
259. Petty, J. Todd; Grossman, Gary D. 2004. Restricted movement by mottled sculpin (pisces: cottidae) in a southern Appalachian
stream. Freshwater Biology. 49: 631-645.
1. We used direct observation and mark-recapture techniques to quantify movements by mottled sculpins (Cottus bairdi) in a 1 km
segment of Shope Fork in western North Carolina. Our objectives were to: (i) quantify the overall rate of sculpin movement, (ii) assess
variation in movement among years, individuals, and sculpin size classes, (iii) relate movement to variation in stream flow and
population size structure, and (iv) quantify relationships between movement and individual growth rates.
2. Movements were very restricted: median and mean movement distances for all sculpin size classes over a 45 day period were 1.3 and
4.4 m respectively. Nevertheless, there was a high degree of intrapopulation and temporal variation in sculpin movement. Movement of
juveniles increased with discharge and with the density of large adults. Movement by small and large adults was not influenced by
stream flow, but large adults where more mobile when their own density was high. Finally, there were differences in the growth
rates of mobile and sedentary sculpins. Mobile juveniles grew faster than sedentary individuals under conditions of low flow and high
density of large adults, whereas adults exhibited the opposite pattern.
3. Our results support the hypothesis that juvenile movement and growth is influenced by both intraspecific interactions with adults and
stream flow. In contrast, adult movement appears to be influenced by competitive interactions among residents for suitable space. The
relationship between movement and growth may provide a negative feedback mechanism regulating mottled sculpin populations in this
system.
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260. Phillips, Michael J.; Swift, Lloyd W., Jr.; Blinn, Charles R. 2000. Best management practices for riparian areas. In: Riparian
management in forests of the continental eastern United States. Lewis Publishers, Boca Raton, FL.: 273-285.
This chapter of a book that summarizes the current state of science and management of riparian zones compares riparian zone
management restrictions and discusses the concepts of Best Management Practices of the Continental Eastern United States as they apply
to a variety of forest activities.
261. Post, D.A.; Grant, G.E.; Jones, J.A. 1998. New developments in ecological hydrology expand research opportunities. EOS,
Transactions, American Geophysical Union. 79(43). 517, 526.
Ecological hydrology is defined as the study of hydrological processes such as flow rates, timing, and pathways of water at various time
scales as they influence ecological processes. Data sets from Long Term Ecological Research sites were used to compare hydrologic
processes in several very different ecosystems. Strong seasonal cycles of precipitation at some sites and its asynchronous timing relative
to evapotranspiration rates results in seasonal streamflow patterns very different form those at Coweeta where precipitation is uniformly
distributed and seasonal streamflow is controlled by summer evapotranspiration. Article reports a study and workshop comparing the
hydrologic records at 8 LTER sites and 6 other locations.
262. Pregitzer, Kurt S.; DeForest, Jared L.; Burton, Andrew J.; Allen, Michael F.; Ruess, Roger W.; Hendrick, Ronald L.
2002. Fine root architecture of nine north American trees. Ecological Monographs. 72(2): 293-309.
The fine roots of trees are concentrated on lateral branches that arise from perennial roots. They are important in the acquisition of water
and essential nutrients, and at the ecosystem level, they make a significant contribution to biogeochemical cycling. Fine roots have often
been studied according to arbitrary size classes, e.g., all roots less than 1 or 2 mm in diameter. Because of the size class approach. the
position of an individual root on the complex lateral branching system has often been ignored, and relationships between the form of the
branching root system and its function are poorly understood.
The fine roots of both gymnosperms and angiosperms, which formed ectomycorrhizae (EM) and arbuscular mycorrhizae (AM) fungal
associations, were sampled in 1998 and 1999. Study sites were chosen to encompass a wide variety of environments in four regions of
North America. Intact lateral branches were collected from each species and 18 561 individual roots were dissected by order, with distal
roots numbered as first-order roots. This scheme is similar to the one commonly used to number the order of streams. Fine root diameter.
length, specific root length (SRL; m/g), and nitrogen (N) concentration of nine North American tree species (Acer saccharum, Juniperus
monosperma, Liriodendron tulipifera, Picea glauca, Pinus edulis, Pinus elliottii, Pinus resinosa, Populus balsamifera, and Quercus alba)
were then compared and contrasted.
Lateral roots <0.5 mm in diameter accounted for >75% of the total number and length of individual roots sampled in all species except
Liriodendron tulipifera. Both SRL and N concentration decreased with increasing root order in all nine species, and this pattern appears
to be universal in all temperate and boreal trees. Nitrogen concentrations ranged from 8.5 to 30.9 g/kg and were highest in the first-order
"root tips." On a mass basis, first-order roots are expensive to maintain per unit time (high tissue N concentration). Tissue N appears to
be a key factor in understanding the C cost of maintaining first- and second-order roots, which dominate the display of absorbing root
length. There were many Significant differences among species in diameter, length, SRL, and N concentration. For example, two
different species can have similar SRL but very different tissue N concentrations. Our findings run contrary to the common idea that all
roots of a given size class function the same way and that a common size class for fine roots works well for all species. Interestingly, fine
root lateral branches are apparently deciduous, with a distinct lateral branch scar. The position of an individual root on the branching root
system appears to be important in understanding the function of fine roots.
263. Qualls, R.G.; Haines, B.L.; Swank, W.T.; Tyler, S.W. 2000. Soluble organic and inorganic nutrient fluxes in clearcut and
mature deciduous forests. Soil Science Society American Journal. 64: 1068-1077.
The mechanisms by which forest ecosystems retain or lose soluble inorganic nutrients after disturbance are well known, but substantial
amounts of soluble organic nutrients may also be released from cut vegetation. Our objective was to compare the leaching of dissolved
organic and inorganic nutrients in cut and mature forest stands and to develop hypotheses about factors controlling the retention of
soluble organic nutrients after disturbance. Solution chemistry was measured for 2 yr after clearcutting a small area in the surrounding
undisturbed deciduous forest on a reference watershed at the Coweeta Hydrologic Laboratory in the Appalachian Mountains.
Concentrations of dissolved organic C (DOC) and N (DON) in slash leachate were 2.6 to 3.2 times the concentrations in throughfall
from undisturbed forest. Concentrations in forest floor, A horizon, and B-horizon solutions from cut plots were 1.2 to 3.8 times those
from undisturbed forest. Dissolved organic P (DOP) concentrations in cut plots were 3.1 and 3.6 times those of uncut plots in solutions
from slash and forest floor, respectively, but did not differ in mineral soil. Fluxes of DOC, DON, and DOP in all strata were greater in
cut plots than uncut plots. Fluxes of DON were greater than those of ammonium plus nitrate N in all strata of both cut and uncut plots.
We hypothesize that the well-recognized retention mechanisms for inorganic nutrients combine with equilibrium adsorption of dissolved
organic matter to efficiently buffer against leaching of both soluble inorganic and organic nutrients after clearcutting.
264. Qualls, R.G.; Haines, B.L.; Swank, W.T.; Tyler, S.W. 2002. Retention of soluble organic nutrients by a forested ecosystem.
Biogeochemistry. 61: 135-171.
63
We document an example of a forested watershed at the Coweeta Hydrologic Laboratory with an extraordinary tendency to retain
dissolve organic matter (DOM) generated in large quantities within the ecosystem. Our objectives were to determine fluxes of dissolved
organic C, N, and P (DOC, DON, DOP, respectively), in water draining through each stratum of the ecosystem and synthesize
information on the physicochemical, biological and hydrologic factors leading to retention of dissolved organic nutrients in this
ecosystem. The ecosystem retained 99.3, 97.3, and 99.0% of water-soluble organic C, N, and P, respectively, produced in litterfall,
throughfall, and root exudates. Exports in streamwater were 4.1 kg ha –1yr-1of DOC, 0.191 kg ha –1yr-1of DOP. Fluxes of DON were
greater than those of inorganic N in all strata. Most DOC, DON, and DOP was removed from solution in the A and B horizons, with
DOC being rapidly adsorbed to Fe and Al oxyhydroxides, most likely by ligand exchange. DON and DOC were released gradually from
the forest floor over the year. Water soluble organic C produced in litterfall and throughfall had a disjoint distribution of half-decay times
with very labile and very refractory fractions so that most labile DOC was decomposed before being leached into the mineral soil and
refractory fractions dominated the DOC transported through the ecosystem. We hypothesize that this watershed retained soluble organic
nutrients to an extraordinary degree because the soils have very high contents of Fe and Al ox hydroxides with high adsorption capacities
and because the predominant hydrologic pathway is downwards as unsaturated flow through a strongly adsorbing A and B-horizon. The
well-recognized retention mechanisms for inorganic nutrients combine with adsorption of DOM and hydrologic pathway to efficiently
prevent leaching of both soluble inorganic and organic nutrients in this watershed.
265. Radtke, Philip J.; Bolstad, Paul V. 2001. Laser point-quadrat sampling for estimating foliage-height profiles in broad-leaved
forests. Canadian Journal of Forest Research. 31(3): 410-418.
A technique for estimating the vertical distribution of foliage area in broad-leaved forests was developed. The technique is similar to
optical point-quadrat sampling, where estimates are based on heights to the lowest leaves above numerous sample locations beneath a
canopy. In optical point-quadrat sampling, heights to lowest leaves are measured with a telephoto lens. Here, heights were measured
using a commercially available laser range-finding instrument. The laser point-quadrat technique was tested in field studies conducted
under broad-leaved forest canopies in western North Carolina and east-central Minnesota, U.S.A. Foliage-height profiles obtained by
laser point-quadrat sampling were consistent with two of four published foliage-height profiles observed in 1995 at the North Carolina
field locations. Total leaf area estimates obtained by laser point quadrats were not significantly correlated with values of leaf area index
estimated by recent litter fall analyses at the North Carolina and Minnesota field locations. Although further evaluation and refinement of
the technique is needed, laser point-quadrat sampling shows promise as a means of obtaining foliage-height profiles at a significantly
reduced effort and with greater accuracy than methods commonly in use today.
266. Radtke, Philip J.; Burk, Thomas E.; Bolstad, Paul V. 2002. Bayesian melding of a forest ecosystem model with correlated
inputs. Forest Science. 48(4): 701-711.
Bayesian melding, a method for assessing uncertainties in deterministic simulation models was augmented to make use of prior
knowledge about correlations between model inputs. The augmentation involved the use of a nonparametric correlation induction
algorithm. The modified Bayesian melding technique was applied to the process-based forest ecosystem computer model PnET-II. The
Bayesian posterior distribution for this analysis did not reflect prior knowledge of input correlations for five input pairs tested unless the
correlations were explicitly accounted for in the Bayesian prior distribution. For other input pairs not known to be correlated prior to the
analysis, numerous significant posterior correlations were identified. For one such pair of model inputs, a moderate posterior correlation
was substantiated by empirical evidence that had not previously been taken into consideration. We conclude that, when possible, efforts
should be made to account for prior knowledge of correlated inputs; however, Bayesian melding may elucidate input correlations in its
posterior sample, even when no prior knowledge of such correlations exists.
267. Rauscher, H. Michael. 1999. Ecosystem management decision support for federal forests in the United States: A review. Forest
Ecology and Management. 114: 173-197.
Ecosystem management has been adopted as the philosophical paradigm guiding management on many federal forests in the United
States. The strategic goal of ecosystem management is to find a sensible middle ground between ensuring long-term protection of the
environment while allowing an increasing population to use its natural resources for maintaining and improving human life. Ecosystem
management has all the characteristics of wicked problems that are tricky, complex, and thorny. Ambiguities, conflicts, internal
inconsistencies, unknown but large costs, lack of organized approaches, institutional shock and confusion, lack of scientific
understanding of management consequences, and turbulent, rapidly changing power centers all contribute to the wickedness of the
ecosystem management paradigm. Given that ecosystem management, like human survival and welfare, is a wicked problem, how can
we proceed to tame it? Managers need to use the same tools that people have always used for handling such problems - knowledge,
organization, judicious simplification, and inspired leadership. The generic theory of decision support system development and
application is well developed. Numerous specific ecosystem management decision support systems (EM-DSS) have been developed and
are evolving in their capabilities. There is no doubt that given a set of ecosystem management processes to support and adequate time
and resources, effective EM-DSS can be developed. On the other hand, there is considerable doubt that sufficiently detailed, explicitly
described and widely accepted processes for implementing ecosystem management can be crafted given the current institutional,
educational, social, and political climate. A socio-political climate in which everyone wants to reap the benefits and no one wants to pay
the costs incapacitates the federal forest management decision-making process. Developing a workable ecosystem management process
and the decision-making tools to support it is probably one of the most complex and urgent challenges facing us today. This paper offers
64
a concise review of the state of the art of decision support systems related to implementing ecosystem management. A conceptual model
of the context in which ecosystem management is expected to function is presented. Next, a candidate for an operational ecosystem
management process is described and others are referenced. Finally, a generic ecosystem management decision support system is
presented and many existing systems briefly described.
268. Reed, Derik J.; Guynn, David G., Jr. 1990. Response of wild turkey hens to bear hunting in western North Carolina. In:
Eversole, Arnold G., ed. Proceedings of the forty-fourth annual conference: Southeastern Association of Fish and Wildlife
Agencies.1990 October 21-24; Richmond, VA. Baton Rouge, LA: Louisiana Department of Wildlife and Fisheries: 304-309.
Movements of eastern wild turkey hens (Meleagris gallapavo silvestris) were monitored using radio telemetry on the Coweeta
Hydrologic Laboratory in Western North Carolina during 1985-87. Turkeys (N = 15) responded to the use of dogs for bear hunting by
temporarily abandoning portions of their established home ranges and relocating to unhunted areas during the 2-month season. Hens
returned to abandoned areas soon after hunting ceased and when dogs were not used for hunting. No mortality of turkeys was detected
during bear season. The rapid return of hens to former ranges suggests that unhunted habitats were crowded or that preferred habitats on
Coweeta were not available to turkeys during bear hunts.
269. Reeves, R. Marcel. 1995. New Carabodes from eastern United States (Acari: Oribatida: Carabodidae). Acarologia. 36(1): 83-92.
Adults of two new species of Carabodes, C. spiniformis and C. coweetaensis, are described. Both were most abundant in coniferous or
hardwood leaf litter, with the former also common in rotten wood.
270. Reich, Peter B.; Ellsworth, David S.; Walters, Michael B.; Vose, James M.; Gresham, Charles; Volin, John C.; Bowman,
William D. 1999. Generality of leaf trait relationships: a test across six biomes. Ecology. 80(6): 1955-1969.
Convergence in interspecific leaf trait relationships across diverse taxonomic groups and biomes would have important evolutionary and
ecological implications. Such convergence has been hypothesized to result from trade-offs that limit the combination of plant traits for
any species. Here we address this issue by testing for biome differences in the slope and intercept of interspecific relationships among
leaf traits: longevity, net photosynthetic capacity (Amax), leaf diffusive conductance (Gs), specific leaf area (SLA), and nitrogen (N)
status, for more than 100 species in six distinct biomes of the Americas. The six biomes were: alpine tundra-subalpine forest ecotone,
cold temperate forest-prairie ecotone, montane cool temperate forest, desert shrub land, subtropical forest, and tropical rain forest.
Despite large differences in climate and evolutionary history, in all biomes mass-based leaf N (Nmass), SLA, Gs, and Amax were positively
related to one another and decreased with increasing leaf life span. The relationships between pairs of leaf traits exhibited similar slopes
among biomes, suggesting a predictable set of scaling relationships among key leaf morphological, chemical, and metabolic traits that
are replicated globally among terrestrial ecosystems regardless of biome or vegetation type. However, the intercept (i.e., the overall
elevation of regression lines) of relationships between pairs of leaf traits usually differed among biomes. With increasing aridity across
sites, species had greater Amax for a given level of Gs and lower SLA for any given leaf life span. Using principal components analysis,
most variation among species was explained by an axis related to mass-based leaf traits (Amax, N, and SLA) while a second axis reflected
climate, Gs, and other area-based leaf traits.
271. Reich, Peter B.; Walters, Michael B.; Ellsworth, David S.; Vose, James M.; Volin, John C.; Gresham, Charles; Bowman,
William D. 1998. Relationships of leaf dark respiration to leaf nitrogen, specific leaf area and leaf life span: a test across biomes and
functional groups. Oecologia. 114: 471-482.
Based on prior evidence of coordinated multiple leaf trait scaling, we hypothesized that variation among species in leaf dark respiration
rate (Rd) should scale with variation in traits such as leaf nitrogen (N), leaf life-span, specific leaf area (SLA), and net photosynthetic
capacity (Amax). However, it is not known whether such scaling, if it exists, is similar among disparate biomes and plant functional types.
We tested this idea by examining the interspecific relationships between Rd measured at a standard temperature and leaf life-span, N,
SLA, and Amax for 69 species from four functional groups in six biomes traversing the Americas. Area-based Rd was positively related to
area-based leaf N within functional groups and for all species pooled, but not when comparing among species within any site. At all
sites, mass-based Rd (Rd-mass) decreased sharply with increasing leaf life-span and was positively related to SLA and mass-based Amax
and leaf N (leaf Nmass). These intra-biome relationships were similar in shape and slope among sites, where in each case we compared
species belonging to different plant functional groups. Significant Rd-mass-Nmass relationships were observed in all functional groups, but
the relationships differed, with higher Rd at any given leaf N in functional groups with higher SLA and shorter leaf life-span. Regardless
of biome or functional group, Rd-mass was well predicted by all combinations of leaf life-span, Nmass and/or SLA. At any given SLA, Rdmass rises with increasing Nmass and/or decreasing leaf life-span; and at any level of Nmass, Rd-mass rises with increasing SLA and/or
decreasing leaf life-span. The relationships between Rd and leaf traits observed in this study support the idea of a global set of predictable
interrelationships between key leaf morphological, chemical, and metabolic traits.
272. Reynolds, B.C.; Hunter, M.D. 2001. Responses of soil respiration, soil nutrients, and litter decomposition to inputs from canopy
herbivores. Soil Biology & Biochemistry. 33: 1641-6152.
65
We tested whether inputs from canopy herbivores would affect soil processes such as respiration, nutrient cycling, and decomposition
along an elevation gradient. The five treatments we used were frass additions, throughfall additions, removal of all litter that fell during
the study, removal of greenfall that fell during the study, and controls. Soil respiration was significantly reduced on low and mid
elevation sites in litter exclusion greenfall exclusion and throughfall addition treatments (from 0.846 g CO2/m2/h for controls to 0.618,
0.667, and 0.708 g CO2/m2/h. respectively, for the three treatments). Throughfall additions containing PO 4 and NH4 contributed to
significant increases in PO4 (as much as 0.737 mg/l in 100 ml KCI extract greater then controls), but decreases in NO3, (0.306 mg/1 in
100 ml KCI extract less than controls), in soil solution samples compared to controls. We observed no significant treatment effects on
litter decomposition. Precipitation and temperature influenced soil respiration, but both factors showed a significant interaction with
elevation. Phosphate concentrations in soil solutions differed significantly with elevation (low elevation mean 0.097 mg/1, mid elevation
mean 0.192 mg/1). Elevation had no significant effect on decomposition.
273. Reynolds, Barbara C.; Crossley, D.A., Jr. 1995. Use of a canopy walkway for collecting arthropods and assessing leaf area
removed. Selbyana. 16(1): 21-23.
Canopy walkways are wooden platforms and connecting bridges that provide access to the upper canopy of mature trees. Canopy
walkways were constructed at the Coweeta Hydrologic Laboratory in the Southern Appalachian mountains to study canopy arthropods
and leave area removed in deciduous forest stands. A pole pruner/plastic bag method was used to sample branches bearing leaves and
their attendant arthropods. The arthropods were picked from the samples and the leaves were photocopied. Photocopies were measured
for percentage of leaf area removed. An advantage of the canopy walkway method is that the foliage and leaf-dwelling arthropods from
the upper canopy can be sampled simultaneously, thus providing information on arthropod density per weight of leaves. Vertical
stratification of arthropods can be studied by sampling from smaller platforms built higher in the crowns and by using pole pruners to
sample the lower canopy.
274. Reynolds, Barbara C.; Crossley, D.A., Jr. 1997. Spatial variation in herbivory by forest canopy arthropods along an elevation
gradient. Environmental Entomology. 26(6): 1232-1239.
Spatial variation has recently been recognized as an important component in ecological processes. Elevation differences are an obvious
example of spatial variation, but little is known about the influence of elevation on canopy insect herbivory. We examined elevation
effects on canopy insect herbivory in an eastern deciduous forest. Percentage leaf area removed and canopy arthropod guild structures
were measured at 3 sites along an elevation gradient in the southern Appalachians. Acer rubrum L. was sampled at all sites; Quercus
rubra L. at the lowest and highest sites. Upper and lower canopies of A. rubrum were sampled at the highest site. Canopy walkways
were used in most sampling. Our 1st hypothesis was that percentage leaf area removed would decrease as elevation increased because of
decreases in temperature. Percentage leaf area removed decreased significantly for both tree species as elevation increased. We also
hypothesized that percentage leaf area removed would be greater in the lower canopy, because shade leaves are reportedly more
palatable to herbivores. Percentage leaf area removed was significantly greater in the lower canopy compared with the upper canopy of
A. rubrum. Our 3rd hypothesis was that arthropod guild structure would vary along the elevation gradient because of environmental
differences reflecting elevation differences. Arthropod guild structure was significantly different for A. rubrum at all sites but similar for
Q. rubra. Spatial variation, in terms of elevation differences, was shown to have a significant effect on forest insect herbivory and
arthropod guild structure.
275. Reynolds, Barbara, C.; Crossley, D.A., Jr.; Hunter, Mark D. 2003. Response of soil invertebrates to forest canopy inputs
along a productivity gradient. Pedobiologia. 47:127-139.
Previous studies have suggested that herbivory in forest canopies can influence forest floor processes such as nutrient cycling and
decomposition. We studied the response of litter decomposition to a moisture/productivity gradient with manipulations of the effects of
canopy herbivory at the Coweeta Hydrologic Laboratory, North Carolina. Litterbags containing Quercus rubra L. and Acer rubrum L.
litter were placed at three elevations along the gradient and sampled monthly for two years. Microarthropods, nematodes, and litter mass
loss responses to the productivity gradient were measured. The relative abundance of Collembola and three suborders of mites
(Oribatida, Mesostigmata and Prostigmata) was compared across the gradient. Mass loss was greater at the middle and high elevation
sites in both years and was correlated with increased numbers of oribatid mites per gram of litter. The abundance of all the above
microarthropods (of which oribatics were the most common) was also greater on the middle and high elevation sites and greater on twoyear -old litter than on one- year- old litter. Nematode densities were also greater on the older litter. The herbivore inputs study,
simulating the effects of canopy herbivory, included frass additions, throughfall additions, greenfall exclusion, total litter exclusion, and
controls, Experimental additions of frass to plots on the low and middle elevation sites led to an increase in Collembola abundance in
litterbags from those plots. Plots with frass and artificial throughfall additions also showed increased numbers of fungal feeding and
bacterial feeding nematodes in some months. Numbers of oribatid and prostimatid mites were reduced in litter exclusion plots. Results
from these studies suggest not only significant influences of elevation on litter decomposition and soil fauna abundance but direct links
between canopy herbivory and responses in population densities of forest floor biota.
276. Reynolds, Barbara C.; Hunter, Mark D.; Crossley, D.A., Jr. 2000. Effects of canopy herbivory on nutrient cycling in a
northern hardwood forest in western North Carolina. Selbyana. 21(1.2): 74-78.
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In May 1998 an outbreak of sawflies, Periclista sp. (Hymenoptera: Symphyta), occurred in a high-elevation hardwood forest in western
North Carolina. Estimated defoliation of northern red oak (Quercus rubra) and white oak (Q. alba) removed 40% of leaf area. Weights
of frass (insect feces) collected at the site were greater than at a nearby site of lower elevation that was not defoliated. Within a month of
the outbreak, elevated levels of nitrate-nitrogen. (NO3-N) were measured in through fall and resin bag samples from the site and in
stream water draining the affected watershed. The lower elevation control watershed did not show increased levels of nitrate-nitrogen in
through fall, resin bags, or stream chemistry. This study demonstrates that insect defoliators can influence ecosystem-level processes
such as nutrient cycling.
277. Riedel, M.S.; Vose, J.M.; Leigh, D.S. 2003. The road to TMDL is paved with good intentions-Total maximum daily loads for a
wild and scenic river in the southern Appalachians. In: Proceedings of the Total maximum daily load environmental regulations II; 2003
November 8-12; Albuquerque, New Mexico; St. Joseph, Michigan: American Society of Agricultural Engineers: 356-366.
We monitored water quality in the Chattooga River Watershed (NE Georgia, NW South Carolina, and SW North Carolina) to compare
sediment TMDLs with observed water quality. A judicial consent decree required the EPA to establish TMDLs in one year. The EPA
was unable to fully characterize the sediment budgets of these streams and consequently issued phased sediment TMDLs which can be
revised “… because information on the actual contributions of sediment to the Chattooga River Watershed from both point and nonpoint
sources will be much better characterized in the future.” The EPA listed streams as sediment impaired based upon aquatic indicator
species data and relied upon total suspended solids (TSS) data and modeling to established the sediment TMDLs. We found that TSS
concentrations do not reflect mineral sediment concentrations because the organic and mineral components of TSS were highly variable
between streams. TSS in forested streams could get quite high and were largely organic whereas TSS in streams more heavily impacted
by land use change and roads were mostly mineral sediment. TSS and mineral sediment in a stream listed as being sediment impaired
were significantly lower than streams listed as being only threatened. We also monitored bed material transport and sampled sediment
mineralogy on one of our study streams. The sand and fine gravel in this stream were very dynamic. In-stream scour and deposition
occurred frequently. No in-stream deposition occurred during small events; when road runoff was negligible. During larger events, road
runoff and in-stream sediment deposition occurred. This suggests that the existing sediment TMDLs may not address the causes of
sediment impairment of the aquatic ecosystems. The EPA’s issuance of phased sediment TMDLs was insightful because it
acknowledged our lack of understanding of the impacts of land usage and sediment dynamics on streams in the Chattooga River
watershed.
278. Riedel, Mark S.; Verry, Elon S.; Brooks, Kenneth N. 2002. Land use impacts on fluvial processes in the Nemadji River
Watershed. Hydrological Science and Technology. 18(1-4): 197-205.
The Nemadji River drains 1100 km2 of eastern Minnesota and northeastern Wisconsin. Channel incision and mass wasting are natural
responses to glacial rebound in this area and account for more than 95% of the annual sediment load. However, the clay and sand
delivered by the Nemadji to Lake Superior has increased over the past 150 years. We researched land use history across the upper 520
km2 of the Nemadji River Watershed, surveyed channel characteristics, identified relic channels, and employed dendrochronology to
date floodplains and terraces. Results indicate that two episodes of channel incision began propagating through the Nemadji River and its
tributaries. One associated with timber harvesting in the mid 1800’s and another associated a large fire in 1894. Streams impacted by
incision had increased slope, reduced sinuosity, increased entrenchment, and reduced width depth ratios. Subsequent erosion from steep
banks, mass wasting, and upstream incision provides sediment and space needed for the reconstruction of stable channels. The new
channels are similar to the relic channels and unimpacted streams. Historical increases in water yield, particularly bankfull discharge,
initiated the channel incision. This occurred with the onset of basin scale land use conversion in the 1850’s. Forest fires in 1894 and
1918 and agricultural land use conversion during the early 1900’s initiated additional episodes of channel incision.
279. Riedel, Mark S.; Vose, James M. 2002. The dynamic nature of sediment and organic constituents in TSS. In: Proceedings
national water quality monitoring council national monitoring conference 2002, Building a framework for the future; 2002 May 20-23;
Madison, WI: National Water Quality Monitoring Council: 1-14.
The Chattooga River Watershed, located in NE Georgia, NW South Carolina, and SW North Carolina, contains some of the most scenic
and valuable water resources in the region. The Chattooga River is designated as a wild and scenic river and serves as the headwaters for
water supplied to numerous cities. The mix of public and private lands presents considerable challenges to addressing sources of stream
degradation. The EPA has listed several streams in the Chattooga Watershed as being impaired by suspended sediment and has
established Total Maximum Daily Loads (TMDLs). These TMDLs are based upon determining acceptable levels of suspended sediment;
however, TSS was used as a surrogate for suspended sediment. We are using continuous monitoring of flow and sampling TSS,
suspended sediment, and particulate organic matter on four tributaries of the Chattooga River to determine the nature of TSS loading in
these streams. We have found that TSS concentrations do not necessarily reflect suspended sediment concentrations. The organic and
mineral components of TSS vary between streams. While the benchmark, forested stream in our study did have lower levels of TSS, it
did have relatively high TSS levels during storm events, similar to those impacted streams. However, organic matter was a
proportionately larger component of TSS in the forested streams whereas mineral sediment comprised the greatest fraction of TSS in
streams more heavily impacted by land use change and roads. The streams listed as threatened or impaired had significantly higher levels
of TSS than the benchmark stream. However, TSS and mineral sediment in one of the impaired streams were significantly lower than a
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stream listed as only being threatened. The relevance of a sediment TMDL based on suspended load is questionable because the
sediment impacts to the streams biota and aquatic habitat are caused by bedload.
280. Riedel, Mark S.; Vose, James M. 2002. Forest road erosion, sediment transport and model validation in the southern
Appalachian. In: Second federal interagency hydrologic modeling conference; 2002 July 28- August 1; Las Vegas, NV. Subcommittee
on Hydrology, United States Advisory Committee on Water Information: 10A-1-10A-12.
The Conasauga River Watershed, located in northern Georgia and southern Tennessee, has on of the most diverse aquatic ecosystems in
this region and is currently being considered for designation as a wild and scenic river. The Conasauga River also serves as a major
source of drinking water for numerous large cities. Due to the close proximity with the cities of Knoxville, Atlanta, and Chattanooga,
intensive public usage, and high quality of this aquatic resource, the United States Department of Agriculture (USDA) Forest Service has
designated the Conasauga River as one of the twelve large-scale watershed restoration projects in the nation. This is warranted as the
Conasauga River is experiencing excessive sedimentation from the erosion of private agriculture lands, stream banks, and forest roads.
We are working with an erosion model, the Sediment Tool, to facilitate decision-making in the restoration of forest roads. The sediment
tools, and its parent model the Watershed Characterization System (WCS), were developed by the US Environmental Protection Agency
(EPA). The Sediment Tool is a spatially explicit, GIS based, finite element, lumped parameter model which generates estimates of soil
erosion, sediment routing and sediment yield. We applied WCS along segments of thirteen mountain roads in the Conasauga Watershed.
The segments provide replication of road types under a variety of usage levels, road base materials, and slopes. We sampled overland
flow from each segment for total suspended solids (TSS) and surveyed all pertinent road characteristics. While we were able to
qualitatively calibrate the model, predicted sediment yields were typically much greater than observed data. Model results improved with
digital elevation model (DEM) and computational grid resolution. Error analysis indicated that model sensitivity is limited by the
governing equations within the model and the resolution of the input data. The model currently employs the universal soil loss equation
(USLE) to estimate soil erosion and empirical sediment yield equations to transport sediment. These empirical equations were not
developed for application on aggregate road surfaces. DEM resolution will also present problems in routing the sediment to streams.
Streams in the study areas are only one two three meters wide. Floodplains adjacent to these streams are typically four or five meters
wide and frequently, trap sediment-laden runoff before it reaches the streams. Current efforts to improve upon the model include an
adaptation of the process based Water Erosion Prediction Project (WEPP) model and attainment of finer resolution DEM data that will
more accurately represent the roads surfaces.
281. Riedel, Mark S.; Vose, James M. 2003. Collaborative research and watershed management for optimization of forest road best
management practices. In: International conference on ecology and transportation; 2003 August 24-29; Lake Placid, NY. Federal
Highway Administration. 148-158. Chapter 5.
The Coweeta Hydrological Laboratory, USFS Southern Research Station, worked with state and local agencies and various organizations
to provide guidance and tools to reduce sedimentation and to facilitate restoration of the 1900km2 Conasauga River watershed in
northern Georgia and southern Tennessee. The Conasauga River has the most diverse aquatic ecosystem of any river in the region and is
currently being considered for designation as a Federal wild and scenic river. The watershed is encircled and dissected by highways and
roads, and receives intense recreational, industrial, and agricultural use from the surrounding human population.
Unpaved roads have been found to account for more than 80 percent of stream sedimentation in the forested lands of this region.
Collaborative efforts of research and management focused on developing sediment yield models, prioritizing road restoration, and
reducing sediment yields from roads to streams. Model development facilitated identification of highly erosive roads and prediction of
sediment yield reductions following reconstruction of forest roads.
We monitored sediment yield and transport from a wide variety of existing forest roads during autumn 2001. We used these data for
model validation. We then used the model to characterized roads by erosion susceptibility and to prioritize roads for reconstruction.
During the summer of 2002, we completed reconstruction and installation of best management practices along more than 20 miles of
forest roads. We monitored sediment yield from these roads through autumn 2002. Simulated estimates of sediment yield from the
reconstructed roads were severely limited by the resolution and quality of available data and the sediment transport algorithms employed
in the model. Despite a 46 percent increase in rainfall, from the pre to post-treatment period, road reconstruction reduced sediment yield
by 70 percent.
282. Riedel, Mark S.; Vose, James M.; Bolstad. 2004. Characterizing hysteretic water quality in southern Appalachian streams. In:
Proceeding 2004 national water quality monitoring conference, United States Advisory Committee on water information. National Water
Quality Monitoring Council. Chattanooga, TN:
Water quality in mountain streams of the southern Appalachians varies seasonally and with storms. In an effort to validate Total
Maximum Daily Loads (TMDLs) for sediment in the Chattooga River Watershed (NE Georgia, NW South Carolina, and SW North
Carolina), we studied four tributary streams over an eighteen-month period. Two of the streams had completely forested watersheds; one
stream was a benchmark with exceptional water quality for the purposes of TMDL establishment while the other was impaired by
excessive sedimentation. The third stream, with a completely forested watershed, was adjacent to a gravel road. This stream was
threatened by excessive sedimentation. The fourth, while mostly forested, had residential development and gravel roads in its
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riparian corridor. This stream was also threatened by excessive sedimentation. We measured stream flow continuously and sampled
Total Suspended Solids (TSS) to characterize the hydrology and water quality of these streams during baseflow and storm flow
conditions. TSS data on the benchmark stream and a forested stream exhibited strong hysteresis and were elevated on the rising limbs of
hydrographs and declined rapidly on the recession limbs. While there was weak hysteresis apparent in the constituent concentrations and
loadings of the impaired streams, it was not statistically significant. Thus, we could not simply characterize loadings with typical
constituent vs. discharge rating curves. We filtered TSS and discharge data into rising and recession limb data based upon hydrograph
slope and analyzed the data separately. We constructed a series of rating curves based upon hydrograph thresholds that allow us to
predict loadings as a function of hydrograph dynamics. This modified approach facilitates the establishment of TMDLs because the
hydrograph threshold-rating curves can be used to directly link loading rates to discharge frequency and duration relationships
283. Rincón, P.A.; Grossman, G.D. 2001. Intraspecific aggression in rosyside dace, a drift feeding stream cyprinid. Journal of Fish
Biology. 59: 968-986.
Individual rosyside dace Clinostomus funduloides in a semi-natural, artificial stream displayed substantial differences in their
aggressiveness and could be classified as (1) non-aggressive (NA, 18 of 30 rosyside dace), (2) moderately aggressive (MA, 9 of 30) and
(3) highly aggressive (HA, 3 of 30). Rosyside dace groups, however, did not exhibit linear dominance hierarchies and fish size was only
weakly correlated with the number of aggressive acts performed per individual. Small rosyside dace (<56 mm LF) were always nonaggressive, but larger fish were present in all three-aggression classes. The difference in size between the contestants was significantly,
although not very strongly, correlated with the probability of winning an agonistic interaction (r 2= 0.39). Aggressive rosyside dace may
have ultimately gained higher fitness than less aggressive ones. HA individuals occupied the upstream-most position within foraging
groups significantly more often than other rosyside dace. This location should be the most profitable one because its occupant will be the
first to encounter prey. HA rosyside dace also occupied significantly higher focal velocities that were closer to energetic optima than MA
and NA ones. They also had greater foraging rates and were less solitary than less aggressive fish, but these differences only were
significant at the P=0·066 and P=0·081 level, respectively. Finally, HA fish performed significantly more aggressive acts and feedings
backwards than other individuals. Despite these differences, the effects of intraspecific aggression in rosyside dace appeared less
substantial than those that have been observed in stream salmonids.
284. Rincón, P.A.; Hughes, N.F.; Grossman, G.D. 2000. Landscape approaches to stream fish ecology, mechanistic aspects of
habitat selection and behavioral ecology. Ecology of Freshwater Fish. 9: 1-3.
Introduction and commentary.
285. Rincón, Pedro, A.; Grossman, Gary D.; 1998. The effects of rainbow trout (Oncorhynchus mykiss) on the use of spatial
resources and behavior of rosyside dace (Clinostonus funduloides). Archive Hydrobiology. 141(3): 333-352.
Rainbow trout (Oncorhynchus mykiss) and rosyside dace (Clinostomus funduloides) exhibit substantial overlap in microhabitat use in
Coweeta Creek, North Carolina, USA. We conducted a replicated experiment in an artificial stream to assess the effects of both the
presence of rainbow trout and dace density on: 1) microhabitat use, 2) agonistic behavior, 3) social behavior and 4) feeding rates of dace.
Our results demonstrated that microhabitat use of dace was highly variable both among competition treatments within a replicate and for
the same competition treatment among replicates. Moreover, the pattern of the differences between competition treatments was not
consistent among replicates. As a result, we detected a significant effect of experimental replicate on dace microhabitat use but no
significant competition effect. Trout had little effect on the behavior of dace and intraspecific aggression was much more common than
interspecific aggression. There were strong inter-individual differences in the agonistic behavior of dace, and 94 of the 127 aggressive
individuals per replicate. We detected few significant acclimation or time of day effects. The significant differences in microhabitat use
and behavior observed with replicates appeared to be a consequence of differential initial settlement patterns of dace or the presence of
one or two highly aggressive dace in treatments. Hence, we do not believe that interspecific competition with rainbow trout has a strong
effect on microhabitat use by dace in Coweeta Creek.
286. Risley, Lance S. 1990. A relationship among potassium, calcium, and trace elements in tree leaves and associated canopy
arthropods. Journal of Entomological Science. 25(3): 439-449.
There is a paucity of information that describes the relationship between the suite of nutrient elements in tree foliage and associated
arthropod assemblages. Foliage from chestnut oak (Quercus prinus), hickories (Carya spp.) yellow poplar (Liriodendron tulipifera), red
maple (Acer rubrum), and flowering dogwood (Cornus florida) and associated canopy arthropods were collected in an undisturbed and a
15 yr-old successional forested watershed and analyzed for K, Ca, Mn, Fe, Cu, Zn, Rb, and Sr. Foliar Mn and Sr were found in higher
concentrations in the undisturbed watershed. Foliage from hickories was generally higher in concentrations of metals (Mn, Fe, Cu, Zn)
compared with other tree species. Dogwood foliage had significantly higher concentrations of Ca and significantly lower concentrations
of Mn than other tree species (P<0.05). Concentrations of foliar elements in herbivore-damaged and undamaged leaves did not differ
significantly (P>0.05). Concentrations of elements in and among arthropod feeding categories varied substantially such that no trends
were apparent among tree species and between watersheds. The most apparent trend among arthropod feeding categories was the
relatively large accumulation of K in chewing herbivores (primarily caterpillars). In general, there appeared to be increases in K, Fe, Cu,
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and Zn concentrations from primary producers to consumers. This study contributes to arthropod nutritional ecology and to defining the
role of canopy arthropods in forest ecosystem nutrient cycles.
287. Rivenbark, B. Lane; Jackson, C. Rhett. 2004. Average discharge, perennial flow initiation, and channel initiation-small
southern Appalachian basins. Journal of the American Water Resources Association. 40(3): 630-646.
Regional average evapotranspiration estimates developed by water balance techniques are frequently used to estimate average discharge
in ungaged streams. However, the lower stream size range for the validity of these techniques has not been explored. Flow records were
collected and evaluated for 16 small streams in the Southern Appalachians to test whether the relationship between average discharge
and drainage area in streams draining less than 200 acres was consistent with that of larger basins in the size range (> 10 square miles)
typically gaged by the U.S. Geological Survey (USGS). This study was designed to evaluate predictors of average discharge in small
ungaged streams for regulatory purposes, since many stream regulations, as well as recommendations for best management practices, are
based on measures of stream size, including average discharge. The average discharge/drainage area relationship determined from gages
on large streams held true down to the perennial flow initiation point. For the southern Appalachians, basin size corresponding to
perennial flow is approximately 19 acres, ranging from 11 to 32 acres. There was a strong linear relationship (R-2 = 0.85) between
average discharge and drainage area for all streams draining between 16 and 200 acres, and the average discharge for these streams was
consistent with that predicted by the USGS Unit Area Runoff Map for Georgia. Drainage area was deemed an accurate predictor of
average discharge, even in very small streams. Channel morphological features, such as active channel width, cross-sectional area, and
bankfull flow predicted from Manning's equation, were not accurate predictors of average discharge. Monthly baseflow statistics also
were poor predictors of average discharge.
288. Rivers, Christopher T.; Van Lear, David H.; Clinton, Barton D.; Waldrop, Thomas A. 1999. Community composition in
canopy gaps as influenced by presence or absence of Rhododendron Maximum. In: Haywood, James D., ed. In: Proceedings of the tenth
biennial southern silvicultural research conference; 1999, February 16-18; Shreveport, LA. Gen. Tech. Rep. SRS-30. U.S. Department of
Agriculture, Forest Service, Southern Research Station. 57 p.
The process of gap formation and recolonization plays an important role in the structure and composition in southern Appalachian
forests. The understory composition existing before a disturbance will shape successional patterns of the future stand. Rhododendron
maximum is native to the southern Appalachians and exists as a major understory component in cove forests. Its frequency of occurrence
has been increasing over the past century due to the demise of the American chestnut, heavy logging at the turn of the century, and
suppression of fire. Increasing densities of R. maximum reduced species richness and coverage in the regeneration layer and reduced
recruitment into understory and midstory strata. Woody and herbaceous species regenerated poorly, it at all, under R. maximum’s dense
canopy. Only shade-tolerant woody species like Tsuga Canadensis, and Acer rubrum regenerate in R. maximum thickets, and their
densities are markedly decreased.
289. Roberts, J.H.; Grossman, G.D. 2001. Reproduction characteristics of female longnose dace in the Coweeta Creek drainage,
NC. Ecology of Freshwater Fish. 10: 184-190.
We examined the reproductive characteristics of 38 female longnose dace (Rhinichthys cataractae) from one of the southernmost
populations of this species during two sampling periods in 1999 (ES= March 1999, LS=June 1999). Our data indicated that ES fish had
not spawned, whereas LS fish had begun spawning. The smallest mature female captured was 56 mm SL (age 1+). Mean potential
fecundity differed significantly between ES (mean ± 1 SD = 1832 ±572 oocytes) and LS (mean ±1SD=775±415 oocytes) specimens.
Potential fecundity was positively correlated with both standard length and somatic mass for both ES and LS specimens. Oocyte
diameter frequency histograms indicated that ES specimens possessed two modes of oocytes, whereas LS fish contained two or three
modes. Female longnose dace appeared to spawn more than once during a reproductive season. Oocyte number varied substantially both
among individuals within periods and between periods. The number of Mode II oocytes in ES fish was positively correlated with both
length and somatic mass. Female longnose dace appeared potentially capable of spawning 6+ clutches per year. GSI values for longnose
dace ranged from a high of 21.4% (LS specimen) to 2.4% (ES specimen). Regression analysis demonstrated that there was no evidence
of differential reproductive effort between longnose dace of different size in this population.
290. Rosi-Marshall, Emma J.; Wallace, J. Bruce. 2002. Invertebrate food webs along a stream resource gradient. Freshwater
Biology. 47: 129-141.
The flow of energy through food webs with similar species can vary with both space and time. The river continuum concept (RCC)
provides a useful framework for predicting variability in the biota and food availability along streams. We estimated the flow of organic
matter (g m –2 year –1) through food webs, arrayed along a stream that had different resource inputs. Four sites were sampled along the
Little Tennessee River, North Carolina, U.S.A.: two fifth order sites, one sixth and one-seventh order site. The dominant resource is leaf
detritus in the upstream reach (the upstream fifth order site), algae in the mid-reaches (the downstream fifth and sixth order sites), and
suspended material downstream (seventh order site). Eleven genera, contributing from 50 to 66% of the total macroinvertebrate
secondary production of each site, were studied. We estimated organic matter flow from resource to consumer by combining previously
measured rates of invertebrate secondary production with gut content analyses and assimilation efficiencies. Organic matter flow through
food webs increased in a downstream direction, while the structure of the food webs remained constant. The total food consumed by the
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taxa analyzed increased from 34 g m –2 year –1 at the upstream site to 730 g m –2 year –1 at the most downstream site. We estimate that the
organic matter consumed by the entire macroinvertebrate community ranged from 66 to 1164 g m –2 year –1. These results indicate that
there is variation in the magnitude of organic matter flow through the food webs along this river continuum. The dominant food resource
consumed also changed along the gradient. Leaf detritus consumption decreased from 58% of the total consumption upstream to 6%
downstream, whereas consumption of amorphous detritus increased from 18 to 64%. The proportion of animal material consumed also
increased from 3 to 27%. The total consumption of autochthonous resources (diatoms and filamentous algae) increased along the
continuum (from 6.41 to 34.05 g m –2 year –1). We conclude that these results are related to variation in resource availability, dietary
shifts, and invertebrate secondary production. These results link resource availability to energy flow, a relationship originally suggested
by the RCC.
291. Ross, Gary N. 1998. Butterfly social clubs. Holarctic Lepidoptera. 5(1): 22.
Butterflies may be observed gathering in an apparent social behavior at moist sites. These males are actually gathering fluids rich in
nitrogen compounds required for their breeding process.
292. Ross, Gary Noel. 1997. Preliminary inventory of the butterflies of Coweeta Hydrologic Laboratory, Nantahala National Forest,
NC. News of the Lepidopterists' Society. 39(4): 70-71, 88.
A survey of Coweeta's butterfly life had not been undertaken prior to this inventory. The author visited the site twice: September 17 - 18,
1990 and August 13 - September 1, 1996. A total of 50 species of butterflies and skippers were identified and observed for level of
abundance.
293. Ryan, M.G.; Linder, S.; Vose, J.M.; Hubbard, R.M. 1994. Dark respiration of pines. Ecological Bulletins (Copenhagen). 43:
50-63.
Plant respiration is a large, environmentally sensitive component of the carbon balance for pine ecosystems and can consume >60% of
the carbon fixed in photosynthesis. If climate, genetics, or carbon allocation affects the balance between assimilation and respiration,
respiration will affect net production. Respiration rates for tissues within a tree vary with the number of living cells and their metabolic
activity. For pines, foliage and fine roots have similar respiration rates, with rates for seedlings (60 - 420 nmol C (mol C biomass)-1s-1 at
15oC) higher than those for mature trees (20 - 70 nmol C (mol C biomass)-1s-1 at 15oC). Woody tissue respiration is low compared with
other tissues (<10 nmol C (mol C biomass)-1s-1 at 15oC, for dormant large stems; and 4 - 60 nmol C (mol C biomass)-1s-1 at 15oC, for
small stems, branches, twigs and coarse roots). Reported annual total respiration for the living parts of pine trees uses 32 - 64% of the
annual total of net daytime carbon fixation. The ratio of annual respiration to photosynthesis increased linearly with stand biomass for
young pine stands. Simulations of respiration and assimilation for Pinus eliottii and P. contorta forests support the hypothesis that pines
growing in warmer climates have lower leaf area index because temperature shifts the canopy compensation point. Simulations of these
same stands with increased air temperature in situ suggest that pines growing in cool climates might offset increased foliar respiration
and maintain assimilation by reducing leaf area. Future research on the role of respiration in forest productivity should concentrate on
producing annual budgets at the stand level.
294. Salmore, Alissa K.; Hunter, Mark D. 2001. Elevational trends in defense chemistry, vegetation, and reproduction in
Sanguinaria Canadensis. Journal of Chemical Ecology. 27(9): 1713-1727.
Evaluation of biotic interactions along geographic gradients reveals that pressure on plant populations by herbivores and pathogens
increases as latitude decreases, and is accompanied by a parallel increase in the number and toxicity of alkaloid-bearing plants. We
compared rhizome alkaloid content with plant reproductive and vegetative characters in Sanguinaria canadensis (Papaveraceae) along
an elevational gradient over two growing seasons to ascertain 1) if alkaloid production in bloodroot varies among populations and
systematically with elevation, and 2) if there exists a correlation between isoquinoline alkaloid, vegetative and reproductive production.
In general, alkaloid content in bloodroot rhizomes declines with elevation increases with rhizome water content, varies by site, and
fluctuates seasonally with plant growth and reproduction. Alkaloid content was positively correlated with vegetative and reproductive
effort with few exceptions. Analysis of total protopine and benzophenanthridine alkaloid concentrations revealed generally similar
patterns as those of individual alkaloid concentrations, although significant differences did appear between individual alkaloid
concentrations.
295. Salmore, Alissa K.; Hunter, Mark D. 2001. Environmental and genotypic influences on isoquinoline alkaloid content in
Saguinaria Canadensis. Journal of Chemical Ecology. 27(9): 1729-1747.
In a common garden, we investigated genetic and environmental influences on alkaloid production using Sanguinaria Canadensis as a
model. Nutrient and shade regimes were applied to replicated clones over one growing season, and induction of alkaloid production in
bloodroot was tested on a whole plant basis using jasmonic acid as an elicitor. Alkaloid concentrations increased with decreasing light
intensity and fertilizer levels. Induction was not achieved by foliar application of jasmonic acid. Genetic influences represented by clone
effects may be indicated by variation in alkaloid concentration by clone, but this experimental design did not allow us to distinguish
genetic from pre-experiment environmental influences on the rhizomes.
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296. Sampson, D.A.; Vose, J.M.; Allen, H. L. 1998. A conceptual approach to stand management using leaf area index as the
integral of site structure, physiological function, and resource supply. In: Proceedings of the ninth biennial southern silvicultural research
conference; 1997 February 25-27; Clemson, SC. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research
Station. 447-451.
Stand management involves manipulation of factors that are thought to control ecophysiological mechanisms determining forest growth
and function. Stand leaf area index can be used to assess current growth, as well as site growth potential based on the perceived ability of
the stand to respond to silvicultural manipulation (e.g., fertilization). We sampled the leaf are index (LAI) in 30 plots for each of six
forest cover-types across the Southeast to examine natural variability in LAI. The mean index ranged from 3.5 to 5.1 m 2m2 (projected);
spruce-fir had the lowest while maple-beech-birch had the highest. We present a conceptual model that relates LAI to site resources,
occupancy, and shade tolerance to initiate discourse and development of diagnostic tools for evaluating site-specific determinants of
forest growth. Simulations from a process model suggest that biologically achievable LAI may not be optimal LAI for maximum growth.
297. Alexei, Sankovski; Pridnia, Michael. 1995. A comparison of the southern Appalachian (U.S.A.) and southwestern Caucasus
(Russia) forests: influences of historical events and present environment. Journal of Biogeochemistry. 22: 1073-1081.
The Southern Appalachian (North America) and Southwester Caucasus (Eastern Europe) forests have a common origin, the warmtemperate Tertiary forests, but a different history of development. The Southwestern Caucasus forests experienced a dramatic species
loss at the Tertiary, while Tertiary flora of the Appalachian region was preserved without major changes. Certain similarities and
differences between the flora and vegetation of the Southern Appalachians and Southwestern Caucasus can be attributed to the Tertiary
and post-Tertiary history of both regions. The similarities include the species-to-genus and species-to-families ratios and the floristic
composition. The differences include taxonomic diversity and percentage of tree taxa.
298. Santee, William R.; Monk, Carl D. 1981. Stem diameter and dry weight relationships in Tsuga canadensis (L.) Carr. Bulletin of
the Torrey Botanical Club. 108(3): 320-323.
Twenty trees, ranging in diameter from 1.4cm to 26.2cm, were harvested on Coweeta Hydrologic Laboratory. Basal and breast-height
remeasured after felling. Trees were separated into bole, branch, and needle components. Regressions for dry weight of each component
were computed as log-log functions of diameter. Nutrient concentrations of 15 elements were analyzed from needle, branch, bark, wood,
and cone components.
299. Schaberg, Rex H.; Holmes, Thomas P.; Lee, Karen J.; Abt, Robert C. 1999. Ascribing value to ecological processes: an
economic view of environmental change. Forest Ecology and Management. 114: 329-338.
Decisions made by individual landowners and public land managers can have a significant impact on the rates of ecological change.
Interdisciplinary cooperation is desirable if economists and ecologists are to correctly interpret the impacts of individual choices for
landscape management. This paper reports results from two studies of the residents of North Carolina, which contrast individual
preferences for utilitarian forest benefits and financial returns with less tangible benefits of forest amenities and ecosystem stability. One
study reports preliminary findings from a forest-benefit mail survey on the Nantahala and Pisgah National Forests; the second study
presents an analysis of harvest decisions by private landowners. Economic methods pertinent to valuation of environmental goods are
briefly considered. Individual behavior is described which suggests that segments of the public recognize welfare benefits specifically
from forest amenities, and from natural production of environmental goods and services. The two studies suggest how economic tools
may be extended to help quantify complex social and biological values associated with ecological processes.
300. Schofield, Kate A.; Pringle, Catherine M.; Meyer, Judy L.; Sutherland, Andrew B. 2001. The importance of crayfish in the
breakdown of rhododendron leaf litter. Freshwater Biology. 46: 1-14.
Rhododendron (Rhododendron maximum) is a common evergreen shrub in riparian areas of the southern Appalachians, where its leaves
can comprise a large proportion of leaf litter in streams. However, they are relatively refractory and generally considered a low quality
food resource for detritivores. Our objective was to assess whether macroconsumers [primarily crayfish (Cambarus bartonii)] influence
rhododendron leaf breakdown in a forested southern Appalachian stream in both summer (when leaves other than rhododendron are
relatively scarce) and autumn (when other leaves are relatively abundant). We conducted two leaf decay experiments, one in summer,
and one in autumn, using pre-conditioned leaves. Macroconsumers were excluded from the benthos of a fourth-order stream using
electric ‘fences’; we predicted that excluding macroconsumers would reduce the decay rate of rhododendron leaves in both summer and
autumn. In both experiments, breakdown rate was lower in exclusion treatments. Macroconsumers accounted for approximately 33 and
54% of rhododendron decay in summer and autumn, respectively. We attribute this effect to direct shredding of rhododendron by
crayfish. Biomass of insect shredders, insect predators, and fungi did not differ between control and exclusion treatments, indicating that
insectivorous sculpins (Cottus bairdi) had no effect on rhododendron decay and that omnivorous crayfish did not exert an indirect effect
via alteration of insect or fungal biomass. The influence of shredding insects varied between summer and autumn. In summer, when
other, more palatable leaf types were not available, rhododendron leaf packs appeared to provide ‘resource islands’ for insect shredders.
There was a significant inverse relationship between insect shredders and leaf pack mass in the summer exclusion treatment: insects
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were the only organisms eating leaves in this treatment and, as shredder biomass increased, remaining leaf pack mass decreased. In the
control treatment, however, we did not see this relationship; here, the effect of insect shredders was presumably swamped by the impact
of crayfish. In autumn, when other leaves ere abundant, insect shredder biomass in rhododendron leaf packs was less than one-third of
summer values. Even at low density, (approximately 2 m –2) crayfish were able to influence an ecosystem process, such as leaf decay, in
both summer and autumn. Given the threatened status of many crayfish species in the United States, this finding is especially relevant.
Even small alterations in crayfish assemblages, whether via loss of native species and/ or introduction of exotic species, may have
significant repercussions for ecosystem function.
301. Schowalter, T.D. 1995. Canopy invertebrate community response to disturbance and consequences of herbivory in temperate
and tropical forests. Selbyana. 16(1): 41-48.
Arboreal invertebrates represent a diverse and functionally important component of forest ecosystems. Many invertebrates respond
rapidly and dramatically to changes in environmental conditions, making these organisms potentially useful indicators of forest
condition. Canopy arthropods also significantly affect canopy structure and ecosystem processes such as primary productivity, nutrient
cycling, and hydrology. Few canopy studies have been designed to address environmental issues such as how changes in land use affect
biodiversity or how changes in canopy biodiversity affect functional integration of forest ecosystems. Assessment of canopy invertebrate
responses to environmental change and their consequences for ecosystem processes requires manipulative experimental approaches with
random replication of independent treatment plots to meet requirements of statistical analyses. This paper describes experimental
approaches for evaluating effects of environmental change on canopy arthropod diversity and species abundances and effects of
herbivores on ecosystem processes. These studies have indicated similar functional interactions in taxonomically distinct temperate and
tropical forest canopies.
302. Schowalter, T.D.; Zhang, Y.L.; Sabin, T.E. 1998. Decomposition and nutrient dynamics of oak Quercus spp. logs after five
years of decomposition. Ecography. 21: 3-10.
Decomposition of oak Quercus spp. logs was compared among log substrates in Oregon, Minnesota, Kansas, and North Carolina during
the first five years on the ground. Decomposition of whole logs averaged 0.069 yr -1, but followed a 2-exponential model, reflecting
qualitative differences among log substrates. Rapid loss from bark substrates contributed to the initial rapid decay rate. Sapwood decay
rate averaged 0.15 yr-1 and dominated the second log decay rate. Heartwood lost only 6% mass during the first five years, for an overall
decay rate of 0.012 yr-1 that likely will represent a longer-term third exponential decay rate. Carbon loss amounted to ca 5 kg yr -1 per 170
kg log. Nutrient concentrations generally declined during the first five years, but nitrogen, sulfur, and sodium accumulated in sapwood
and heartwood during this period. Sulfur content increased in substrates and doubled in whole logs during this 5-yr period. Complex
patterns of nutrient content suggest patterns of microbial colonization and nutrient utilization. Polynomial models were developed to
describe rates of carbon and nutrient flux in log substrates.
303. Scott, Mark C.; Helfman, Gene S. 2001. Native invasions, homogenization, and the mismeasure of integrity of fish
assemblages. Fisheries. 26(11): 6-15.
Human activities, particularly habitat destruction and species introductions, are resulting in increased homogenization of once unique
biogeographic regions. In the southeastern United States, extensive endemism occurs among highland fish species that have specialized
ecologies, are adapted to cool, clear, nutrient-poor conditions, and are sediment-intolerant. Highland streams flow into lower elevation
systems which are often inhabited by more widespread, generalist fish species adapted to warmer, more turbid, fine-sediment-rich, and
nutrient-rich conditions. Common land use practices, such as deforestation, degrade stream habitats and reduce habitat diversity, which
is often correlated with taxonomic and ecological diversity. Habitat homogenization can thus cause assemblage homogenization via loss
of native species and addition of nonindigenous species. However, midpoints in the homogenization process may be characterized by
constant or even increased species diversity because generalist, sediment-tolerant, “native” species invade from downstream areas.
Perusal of a species list for a river system would not reveal such invasions because lists seldom discriminate between upstream and
downstream assemblages in a drainage. Traditional metrics often used in biological assessment, such as species richness (a diversity) and
evenness, should not include invasive species, whether native or exotic. Greater attention should be paid to the actual species present and
their ecological requirements, and to changes in overlap in species occurrence among regions. Aquatic ecosystem integrity can degrade
despite apparent increases in species diversity.
304. Scott, Mark C.; Helfman, Gene S.; McTammany, Mathew E.; Benfield, E. Fred; Bolstad, Paul V. 2002. Multiscale
influences on physical and chemical stream conditions across Blue Ridge landscapes. Journal of the American Water Resources
Association. 38(5): 1379-1392.
Streams integrate biogeochemical processes operating to broad to local spatial scales and long term to short-term time scales. Humans
have extensively altered those processes in North America, with serious consequences for aquatic ecosystems. We collected data on
Upper Tennessee River tributaries in North Carolina to: (1) compare landuse and landscape geomorphology with respect to their ability
to explain variation in water quality, sedimentation measures, and large woody debris; (2) determine if landscape change over time
contributed significantly to explaining present stream conditions; and (3) assess the importance of spatial scale in examining landuse
influences o streams. Stream variables were related to both landuse and landscape geomorphology. Forest cover accounted for the most
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variation in nearly all models, supporting predictions of nutrient enrichment, thermal pollution, and sedimentation caused by landscape
disturbance. Legacy effects from past catchment disturbance were apparent in sedimentation measures. Nitrogen and phosphorus
concentrations, as well as stream temperature, were lower where riparian buffers had reforested. Models of stream physicochemistry fit
better when predictors were catchment wide rather than more localized (i.e., within 2 km of a site). Cumulative impacts to streams due to
changes in landuse must be managed from a watershed perspective with quantitative models that integrate across scales.
305. Shields, Catherine. 2002. Ozone and atmospheric deposition at Coweeta Hydrologic Lab. In: Proceedings land use and
biodiversity on the Highlands Plateau. A Carolina Environmental Program Report 2002 December 13; Highlands, NC; Highlands
Biological Station: 7-24.
Since passage of the Clean Air Act in 1970, public awareness of air pollution has increased considerably. Monitoring networks have
been established to assess the level of pollution around the United States, and legislation has resulted in a decline of some atmospheric
pollutants, such as sulfate (Lynch et al., 2000; SAMI, 2002). Although it is primarily thought of as an urban problem, air pollutants are
easily spread from urban sources to more rural areas. One of the better-known rural areas with high air pollution is Great Smoky
Mountains National Park (GSMNP), located along the North Carolina Tennessee border. Poor air quality in GSMNP, and throughout
western North Carolina, makes analysis of air pollution levels at sites in the region of particular concern. This paper summarizes ozone
and atmospheric deposition trends at Coweeta Hydrologic Laboratory during the periods 1988-2001 and 1978-2001, respectively.
306. Siler, Edward R.; Wallace, J. Bruce; Eggert, S.L. 2001. Long-term effects of resource limitation on stream invertebrate drift.
Canadian Journal of Fisheries and Aquatic Sciences. 58: 1624-1637.
We examined the effects of resource limitation on stream invertebrate drift by reducing inputs of terrestrial detritus to a headwater
stream in western North Carolina. In the treatment stream, leaf-litter was excluded for 6 years (September 1993 – August 1999), small
woody debris was removed for 2 years (September 1996 – August 1998), and large and small woody debris was removed for 1 year
(September 1998 – August 1999). Invertebrate abundance in the drift was significantly lower in the treatment stream during the study,
but total biomass of invertebrate drift was similar. Although drift densities were higher in the reference stream, a greater proportion of
total benthic invertebrate abundance in the drift was significantly greater in the treatment stream, but scraper proportions were higher in
the reference stream and filterer proportions were similar for the two streams. Combined data from both streams indicated that the
relationship between drift densities and benthic abundance was positive and significant. Our results demonstrate that bottom-up effects
of resource reduction in a detrital-based stream influence invertebrate drift, increasing the proportion of the benthic community
emigrating from the detritus-poor stream.
307. Simons, Theodore R.; Pearson, Scott M.; Moore, Frank R. 2000. Application of spatial models to the stopover ecology of
trans-gulf migrants. Studies in Avian Biology. 20: 4-14.
Studies at migratory stopover sites along the northern coast of the Gulf of Mexico are providing an understanding of how weather,
habitat, and energetic factors combine to shape the stopover ecology of trans-Gulf migrants. We are coupling this understanding with
analyses of landscape level patterns of habitat availability by using spatially explicit models to simulate avian movements through
stopover habitats. The probability that an individual migrant will complete a migration successfully is determined by the bird’s energetic
status and flight morphology, and the quality, quantity, and spatial pattern of habitats encountered during migration. The models evaluate
habitat patches according to their distance from the coast, isolation from other patches of suitable habitat, and habitat quality. Evaluation
procedures have been developed from available data on the arrival condition of migrants, energetic and morphological constraints on
movement, and species-specific habitat preferences. Window analysis and individual-based modeling are used to demonstrate how the
abundance, quality, and spatial pattern of habitats interact with the arrival energetic state of migrants to determine the suitability of
migratory stopover habitats along the northern Gulf coast. Our goal is to understand how landscape-scale patterns of habitat conversion
may be affecting populations of trans-Gulf migrants.
308. Sinsabaugh, Robert L. 1997. Large-scale trends for stream benthic respiration. In: Webster, J.R.; Meyer, J.L., eds. Stream
organic matter budgets. Journal of the North American Benthological Society. 16: 119-122.
This chapter is part of a multi-site analysis of organic matter dynamics in streams. Benthic respiration increased dramatically with
increasing temperature (Q10 = 7.6), suggesting a response related not only to metabolism but also to changes in BOM quality in
response to latitudinal shifts in vegetation.
309. Sponseller, R.A.; Benfield, E.F.2001. Influences of land use on leaf breakdown in southern Appalachian headwater streams: a
multiple-scale analysis. Journal of the North America Benthological Society. 20(1): 44-59.
Stream ecosystems can be strongly influenced by land use within watersheds. The extent of this influence may depend on the spatial
distribution of developed land and the scale at which it is evaluated. Effects of land-cover patterns on leaf breakdown were studied in 8
southern Appalachian headwater streams. Using a GIS, land cover was evaluated at several spatial scales, including the watershed,
riparian corridor, and subcorridors that extended upstream in 200-m increments for 2 km. Breakdown rate for American sycamore
(Plantanus occidentalis) leaf packs varied significantly among sites (k = 0.0051-0.0180/d), but fell within the range reported in the
74
literature for sycamore. Leaf breakdown rate increased at sites with high shredder density and biomass. Further, breakdown rate and
shredder density and biomass were positively related to mean substrate particle size. Several instream variables were related to
watershed-scale features, but leaf breakdown rate was not related to land cover at the watershed scale. Leaf breakdown rate was
inversely related to % nonforested land within riparian subcorridors of ~1 km. Results suggest that the distribution of shredders is critical
to leaf processing in these streams. In some streams, increased sediment inputs resulting from agricultural activity or residential
development in riparian corridors may limit the distribution of shredders and thus influence leaf breakdown rates. Alternatively, nearstream development may alter the quality of allochthonous inputs to streams, and thus indirectly influence the distribution of shredders
and instream processing.
310. Sponseller, R.A.; Benfield, E.F.; Valett, H.M. 2001. Relationships between land use, spatial scale and stream
macroinvertebrate communities. Freshwater Biology. 46(10): 1409-1424.
We examined the influence of land-cover patterns on in-stream physico-chemical features and macroinvertebrate assemblages in nine
southern Appalachian headwater basins characterized by a mixture of land-use practices. Using a geographical information system
(GIS)/remote sensing approach, we quantified land-cover at five spatial scales; the entire catchment, the riparian corridor, and three
riparian 'sub-corridors' extending 200, 1000 and 2000 m upstream of sampling reaches. Stream water chemistry was generally related to
features at the catchment scale. Conversely, stream temperature and substratum characteristics were strongly influenced by land-cover
patterns at the riparian corridor and sub-corridor scales. Macroinvertebrate assemblage structure was quantified using the slope of rankabundance plots, and further described using diversity and evenness indices. Taxon richness ranged from 24 to 54 among sites, and the
analysis of rank-abundance curves defined three distinct groups with high, medium, and low diversity. In general, other
macroinvertebrate indices were in accord with rank-abundance groups, with richness and evenness decreasing among sites with
maximum stream temperature. Results suggest that differences in macroinvertebrate assemblage structure can be explained by landcover patterns when appropriate spatial scales are employed. In addition, the influence of riparian forest patches on in-stream habitat
features (e.g. the thermal regime) may be critical to the distribution of many taxa in headwater streams draining catchments with mixed
land-use practices.
311. Stanko-Golden, K.M.; Swank, W.T.; Fitzgerald, J.W. 1994. Factors affecting sulfate adsorption, organic sulfur formation, and
mobilization in forest and grassland spodosols. Biology and Fertility of Soils. 17: 289-296.
Forest and grassland soils that contained varying amounts of Fe and Al were collected from England and Wales. Fractionation of free Fe
and Al was accomplished to determine which components affected sulfate adsorption. Organic Fe and Al were the dominant fractions in
most soil horizons and high amounts of these organically bound metals and, to some extent, crystalline Fe oxides were associated with
high sulfate adsorption potentials. These adsorption potentials reflected naturally occurring amounts of adsorbed sulfate and ester sulfate.
Overall, the C content exhibited a positive relationship with sulfate adsorption potentials. Soils with a high C content also exhibited high
rates of organic S formation. The rate of organic S mobilization was greater in soils with higher amounts of soluble sulfate. Organic S
was the largest pool and, typically, sulfonate S was the most abundant constituent of the organic pool.
312. Stone, Michael K.; Wallace, J. Bruce. 1998. Long-term recovery of a mountain stream from clear-cut logging: the effects of
forest succession on benthic invertebrate community structure. Freshwater Biology. 39: 151-169.
Changes in benthic invertebrate community structure following 16 years of forest succession after logging were examined by estimating
benthic invertebrate abundance, biomass, and secondary production in streams draining a forested reference and a recovering clear-cut
catchment. Benthic invertebrate abundance was three times higher, and invertebrate biomass and production were two times higher in the
disturbed stream. Comparison of invertebrate community abundance 1, 5 and 16 years after clear-cutting indicated that the proportion of
scrapers had decreased, whereas shredders had increased. Functional group percentage similarity indicated that the invertebrate
community in the disturbed stream 16 years after clear-cutting was more similar to the reference than to that found earlier in the
disturbed stream. The five indices calculated from data collected over the past 16 years, as well as the abundance, biomass and
production data collected during this study, proved to be of differing value in assessing recovery of the disturbed stream from logging.
Percent dominant taxon and EPT (Ephemeroptera, Plecoptera, and Trichoptera) taxon richness failed to show any initial differences
between reference and disturbed streams, indicating that these indices may not be useful for measuring recovery from logging. The
percentage Baetis and shredder-scraper indices showed significant differences only during the 1977 study and suggest recovery by 1982.
The North Carolina Biotic Index showed continued differences during 1982 in the riffle and depositional habitats and recovery by 1993.
Total macroinvertebrate abundance, biomass and production, as well as EPT abundance, indicated continued differences between the
reference and disturbed streams in the 1993 study.
313. Sullivan, N.H.; Bolstad, P.V.; Vose, J.M. 1996. Estimates of net photosynthetic parameters for twelve tree species in mature
forests of the southern Appalachians. Tree Physiology. 16: 397-406.
Leaf gas exchange, temperature, and incident radiation were measured in situ for 20 mature trees of 12 deciduous species spanning a
range of heights from 7.9 to 30.1 m and growing in the southern Appalachian Mountains. Air temperature, water vapor pressure, total
radiation, photosynthetically active radiation, and carbon dioxide concentration were also measured. Estimated mean light-saturated net
assimilation rates (mmol m-2s-1) ranged from 1.7 to 10.3. There were significant differences in both net assimilation rates and quantum
75
yield efficiencies between species, with the understory species C.florida and A. pensylvanicum exhibiting lower net assimilation rates at
saturation and higher estimated quantum yield efficiencies than the other species. We observed curvilinear effects of temperature and
vapor pressure deficit on net assimilation response to light, and these effects varied by species.
314. Sun, Ge; McNulty, Steven G. 1998. Modeling soil erosion and transport on forest landscape. In: Proceedings of conference 29;
1998 February 16-20; Reno, NV: International Erosion Control Association. 187-198.
Century-long studies on the impacts of forest management in North America suggest sediment can cause major reduction on stream
water quality. Soil erosion patterns in forest watersheds are patchy and heterogeneous. Therefore, patterns of soil erosion are difficult to
model and predict. The objective of this study is to develop a user-friendly management tool for land managers to design forest
management activities that may minimize water quality impacts. This system has the capability to predict long-term soil erosion and
sediment transport from hillslopes to stream networks under different climate conditions and forest management scenarios. A
Geographic Information System (GIS) coupled with the Universal Soil Loss Equation (USLE) model was used to facilitate database
development, manipulation, and output display. The 1140 ha watershed was divided into 30 X 30 m grid cells and gross soil erosion was
first predicted by the USLE model for each cell. The Arc/Info GIS utilities are employed to calculate the total mass of sediment moving
from each cell to the nearest stream network. Field measurements were used to develop sediment movement routing functions. This
study concluded that poorly managed roads are the main source of sediment in a forested watershed. The spatial location of forest roads
affected sediment contribution to streams.
315. Sun, G.; McNulty, S.G.; Amatya, D.M.; Skaggs, R.W.; Swift, L.W. Jr.; Shepard, J.P.; Riekerk, H. 2002. A comparison of
the watershed hydrology of coastal-forested wetlands and the mountainous uplands in the Southern US. Journal of Hydrology. 263: 92104.
Hydrology plays a critical role in wetland development and ecosystem structure and functions. Hydrologic responses to forest
management and climate change are diverse in the Southern United States due to topographic and climatic differences. This paper
presents a comparison study on long-term hydrologic characteristics (long-term seasonal runoff patterns, water balances, storm flow
patterns) of three watersheds in the southern US. These three watersheds represent three types of forest ecosystems commonly found in
the lower Atlantic coastal plain and the Appalachian upland mountains. Compared to the warm, flat, and shallow groundwater dominated
pine flatwoods on the coast, the inland upland watershed was found to have significantly higher water yield, Precipitation/Hamon’s
potential evapotranspiration ratio (1.9 for upland vs. 1.4 and 0.9 for wetlands), and runoff/precipitation ratio (0.53 ± 0.092 for upland vs.
0.30 ± 0.0.79 and 0.13 ± 0.094 for wetlands). Streamflow from flatwoods watersheds generally are discontinuous most of the years while
the upland watershed showed continuous flows in most years. Stormflow peaks in a cypress-pine Aatwoods system were smaller than
that in the upland watershed for most cases, but exceptions occurred under extreme wet conditions. Our study concludes that climate is
the most important factor in determining the watershed water balances in the southern US. Topography effects streamflow patterns and
stormflow peaks and volume, and is the key to wetland development in the southern US.
316. Swank, W.T.; Vose, J.M.; Elliott, K.J. 2001. Long-term hydrologic and water quality responses following commercial
clearcutting of mixed hardwoods on a southern Appalachian catchment. Forest Ecology and Management. 143: 163-178.
Long-term changes (~20 years) in water yield, the storm hydrograph, stream inorganic chemistry, and sediment yield were analyzed for a
59 ha mixed hardwood-covered catchment (Watershed 7) in the southern Appalachian mountains (USA) following clearcutting and cable
logging. The first year after cutting, streamflow increased 26 cm or 28% above the flow expected if the forest had not been cut. In
subsequent years, discharge increases declined at a rate of 5-7 cm per year until the fifth year when changes in flow returned to baseline
values. Later in forest succession, between ages 15 and 18 years, both significant increases and decreases in annual water yield were
observed: these discharge dynamics are discussed in relation to vegetation regrowth dynamics. Flow responses predicted from an
empirical regional scale model were within 17% of experimental values during the first 4 years of regrowth. Intra-annual analysis
showed that proportionally larger increases (48%) in flow occurred in the low flow months of August-October. Storm hydrograph
analysis showed that, on an average, initial flow rate and peak flow rates increased 14-15% and stormflow volume increased 10%.
Analyses of stream solute concentrations and catchment nutrient fluxes showed small increases in nutrient losses following clearcutting
and logging. Responses were largest the third year after treatment with annual values of 1.3, 2.4, 2.7, 3.2, 1.4, 0.39. and 2.1 kg ha -1 for
NO3-N, K, Na, Ca, Mg, S, and C1, respectively. Explanations for the retention of nutrients and high ecosystem resistance and resilience
are discussed in relation to internal biogeochemical cycles based on long-term process level studies on the catchment. A second,
sustained pulse of NO3 ¯ to the stream (exceeding post-harvest values) observed later in succession is also discussed in the context of
ecosystem processes. Large increases in sediment yield were measured immediately after road construction due to two major storm
events. Subsequently, during logging, sediment yield from roads was greatly reduced and insignificant when logging activities were
completed. In contrast, cumulative increases in sediment yield were observed downstream over the next 15 years, which illustrate the lag
between pulsed sediment inputs to a stream and the routing of sediments through a stream system. The relevance of sedimentation to
stream sustainability is discussed in the context of long-term responses in the benthic invertebrate community structure and productivity
measured on WS7.
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317. Swank, Wayne. 2000. Forest succession, chap. 11. In: Dissmeyer, George E., ed. Drinking water from forests and grasslands: a
synthesis of the scientific literature. Gen. Tech. Rep. SRS-039, Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern
Research Station: 120-123.
The Safe Drinking Water Act Amendments of 1996 requires States to assess significant potential sources of contamination to drinking
water. Many watersheds supplying water contain complex patterns of mixed land uses. This paper provides information on how various
water quality parameters change with concomitant downstream changes in the mix of land uses from the forested headwater source
through a mixture of farmland practices, increasing road density, and homesites development. The study site is a fifth-order stream
draining to the Little Tennessee River in the Nantahala mountains of western North Carolina.
318. Swank, Wayne T. 1995. Current issues facing foresters in parts of North America. In: Brown, I.R., ed. Forests and water: In:
Proceedings of a discussion meeting; 1994 March 25-27; Edinburgh. Edinburgh: Institute of Chartered Foresters: 129-148.
Present day public expectations, social needs, environmental concerns, and regulations are requiring new approaches to forestry
activities in much of North America. For example, in Canada and the United States there is an emphasis on incorporating ecologically
based concepts, principles, and technology into forest resource planning. Issues or topics related to these changing views of the forest
include biodiversity, ecosystem management, silvicultural regeneration methods, water quality, riparian area management, and forest
sustainability among others. At a global scale, climate change and potential impacts on forest resources are of concern. Research from
the Coweeta Hydrologic Laboratory in the southeast U.S. is used to suggest approaches and provide examples of melding research with
management to address some of these issues.
319. Swank, Wayne T. 1998. Multiple use forest management in a catchment context. In: Cresser, M.; Pugh, K., eds. Multiple land
use and catchment management: In: Proceedings of an international conference; 1996 September 11-13; Aberdeen, Scotland, UK.
Aberdeen, Scotland, UK: Macaulay Land Use Research Institute: 27-37.
This paper presents an analysis of how integrated catchment management can provide a powerful analytical tool for evaluating
alternative mixes of forest uses across multiple scales of space and time. The author 1) reviews the history of multiple use forest
management on public lands in the U.S.; 2) illustrates approaches to multiple use management in a catchment context using past longterm research on Coweeta WS 28, current ecosystem management research on the Wine Spring Creek basin, and regional scale research
in the southern Appalachian region of the U.S. and 3) concludes with suggestions of future needs, opportunities, and approaches
attendant to integrated catchment management.
320. Swank, Wayne T.; Bolstad, Paul V. 1997. Cumulative impacts of land use on water quality in a southern Appalachian
watershed. Journal of the American Water Resources Association. 33(3): 519-533.
Water quality variables were sampled over 109 weeks along Coweeta Creek, a fifth-order stream located in the Appalachian mountains
of western North Carolina. The purpose of this study was to observe any changes in water quality, over a range of flow conditions, with
concomitant downstream changes in the mix of landuses. Variables sampled include pH, HCO32-, conductivity, NO3--N, NH4+-N,
PO43--P, Cl-,Na+, K+, Ca2+, Mg2+, SO42-, SiO2, turbidity, temperature, dissolved oxygen, total and fecal coliform, and fecal
streptococcus. Landcover/landuse was interpreted from 1:20,000 aerial photographs and entered in a GIS, along with information on
total and paved road length, building location and density, catchment boundaries, hydrography, and slope. Linear regressions were
performed to relate basin and near-stream landscape variables to water quality.
Consistent, cumulative, downstream changes in water quality variables were observed along Coweeta Creek, concomitant with
downstream human caused changes in landuse. Furthermore, larger downstream changes in water quality variables were observed during
stormflow when compared to baseflow, suggesting cumulative impacts due to landscape alteration under study conditions were much
greater during storm events. Although most water quality regulations, legislation, and sampling are promulgated for baseflow conditions,
this work indicates they should also consider the cumulative impacts of physical, chemical, and biological water quality during
stormflow.
321. Swank, Wayne T.; Bolstad, Paul V. 2000. Cumulative impacts of land use on water quality in a southern Appalachian
watershed. In: Dissmeyer, George E., ed. Drinking Water from Forests and Grasslands: A synthesis of the scientific Literature. Gen.
Tech. Rep. SRS-39, Asheville, NC: U.S. Department of Agriculture, Forest Service: 120-123.
The safe drinking water act amendments of 1996 requires states to assess significant potential sources of contamination to drinking
water. Many watersheds supplying water contain complex patterns of mixed land uses. This paper provides information on how various
water quality parameters change with concomitant downstream changes in the mix of land uses from the forested headwater source
through a mixture of farmland practices, increasing road density, and homesites development. The study site is a fifth-order stream
draining to the Little Tennessee River in the Nantahala mountains of western North Carolina.
77
322. Swank, Wayne T.; Johnson, Chris E. 1994. Small catchment research in the evaluation and development of forest management
practices. In: Moldan, B.; Cerny, J., eds. Biogeochemistry of small catchments: a tool for environmental research. Scientific Committee
on Problems of the Environment (SCOPE) 51. Chichester, U.K.: John Wiley & Sons Ltd.: 383-408.
The hydrologic literature is replete with examples of the use of small catchment experiments to determine the effects of forest
management practices on water resources. Examination of recent hydrology symposia indicates that approximately 20 percent of the
papers deal with some aspect of land-use activities and hydrologic interactions. This report (1) provides a brief historical background on
the topic; (2) outlines some philosophical and conceptual approaches for using small catchments to evaluate forest management
activities; (3) illustrates the benefits and limitations of these approaches through select examples; and (4) suggests topics that are high
priority for future research.
323. Swank, Wayne T.; McNulty, Steven G.; Swift, Lloyd W., Jr. 1994. Opportunities for forest hydrology applications to
ecosystem management. In: Ohta, Takehiko; Fukushima, Yoshihiro; Suzuki, Masakazu, eds. Proceedings of the International
Symposium on Forest Hydrology; 1994 October 24-28; Tokyo, Japan. Tokyo Japan: International Union of Forestry Research
Organizations, Organizing committee of the International Symposium on Forest Hydrology, 1994: 19-29.
Emerging environmental issues offer new opportunities for linking forest hydrology research to other sciences and applying principles to
meet management needs. We discuss two such topical areas where hydrologic understanding is essential for addressing issues. In the
first one, a lumped parameter model (PnetII-S) is used and validated for forest hydrology and productivity predictions for loblolly pine
(Pinus taeda) at forest stand and regional scales. Utility of the model is then illustrated by applying the model to a potential global
warming scenario predicted by a general circulation model and examination of the consequences for changes in regional
evapotranspiration. Ecosystem management (EM), currently the operating philosophy of the USDA Forest Service, is the second topical
area. We describe our approach to research and management planning and implementation of EM for Wine Spring Creek, a basin in the
Southern Appalachian Mountains. The importance of applying forest hydrologic process information to obtain desired future conditions
for resources is illustrated through a modeling approach for estimating soil erosion and stream sediment loading.
324. Swank, Wayne, T.; Meyer, Judith, L.; Crossley, Jr., Deyree A. (Dac). 2002. Long-term ecological research: Coweeta history
and perspectives. In: Barrett, Gary W.; Barrett, Terry L., eds. Holistic science- The evolution of the Georgia Institute of Ecology (19402000). Taylor & Francis. 143-163. Chapter 8.
The Coweeta Hydrologic Laboratory-Institute of Ecology cooperative research program is one of the longest continuous collaborations
on forest-ecosystem structure and function between a federal agency and academia in the country. Formally established in 1968, the
program continues to mature in scientific scope, interdisciplinary expertise, administrative challenges, and relevance for natural resource
and environmental management. Our objectives in this chapter are to (1) provide a historical context that summarizes the maturation in
research philosophy of the long-term research program at Coweeta, and identifies the people who led the effort; (2) discuss the benefits
and contributions of the collaboration with regard to education and training; (3) and, based on these lessons, suggest some of the
ingredients required to sustain successful long-term ecosystem research into the future. We are frequently asked what is “long-term”
research: we consider the minimum window of investigation for forest ecosystems to include the life span of the forest of interest. This
time frame usually encompasses at least one generation of scientists and frequently two or more generations.
325. Swank, Wayne T.; Tilley, David R. 2000. Watershed management contributions to land stewardship: Case studies in the
southeast. In: Proceedings of the land stewardship in the 21st. century: The contributions of watershed management; 2000 March 13-16;
Tucson, AZ. P-13: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 93-108.
We describe three examples of watershed management studies, at different spatial scales, that provide approaches and information useful
in enhancing natural resource stewardship in the southern Appalachians. A multiple use "pilot" study, initiated 35 years ago at the
Coweeta Hydrologic Laboratory, demonstrates that southern Appalachian forests can be successfully managed for water, timber,
wildlife, and recreation. Added benefits of this small scale (144 ha) watershed study are the education and on-the-ground demonstration
values. A demonstration project of ecosystem management, initiated in the early 1990s on a 1820 ha watershed provides an integrated,
interdisciplinary ecosystem approach to research, planning and management. Organized around themes of ecosystem restoration, forest
sustainability, human and economic values, and ecosystem structure and function, the multifaceted studies are providing new knowledge
and management benefits. More recently, regional scale watershed research was initiated on two river basins within a 70,000 k ² area of
western North Carolina. The goal is to develop a predictive understanding of the social, economic, and environmental factors that drive
land use cover changes and to evaluate the consequences of change for terrestrial and aquatic biodiversity, water quality, and regional
carbon cycles. E'm'ergy, a tool for synthesizing the multiple values of watersheds, is applied to the ecosystem management study.
326. Swank, Wayne T.; Vose, James M. 1994. Long-term hydrologic and stream chemistry responses of southern Appalachian
catchments following conversion from mixed hardwoods to white pine. In: Landolt, Ruth, ed. Hydrologie kleiner Einzugsgebiete:
Gedenkschrift Hans M. Keller. Beitrage zur Hydrologie der Schweiz 35. Bern, Schweizerische: Schweizerische Gesellschaft fur
Hydrologie und Limnologie: 164-172.
78
We summarize nearly 40 years of research on changes in water yield and timing of streamflow and over 20 years of stream chemistry
data following conversion of two mixed deciduous hardwood forests to plantations of eastern white pine. Only 10 years after planting,
annual streamflow from the pine-covered watersheds was less than expected from mixed hardwoods, and, by age 15, water yield
reductions were about 20 cm. Subsequently, annual streamflow reductions frequently exceeded 25-cm. Significant flow reductions
occurred in every month; with the greatest absolute changes in the high flow months and the largest percentage reductions (40%) in the
low flow months. Greater evapotranspiration from pine is due to a much higher leaf area index throughout the year, and, consequently,
greater interception loss in the dormant season and more transpiration loss in early spring and late fall. Flow duration analysis showed
that conversion to pine reduced the frequency of both high and low flows by 33 to 60 percent. Concentrations of most streamwater
solutes were similar between the pine covered watersheds and mature hardwoods. However, nutrient budget comparisons (input-output)
showed net accumulations of 1.2 to 4.4 kg ha-1yr1 for Ca, Mg, K, and Na in pine ecosystems compared to hardwoods. The conservation
of nutrients in pine ecosystems is due to reduced discharge and also greater accretion of nutrients in the vegetation compared to
hardwoods.
327. Swank, Wayne T.; Vose, James M. 1997. Long-term nitrogen dynamics of Coweeta forested watersheds in the southeastern
United States of America. Global Biogeochemical Cycles. 11(4): 657-671.
We analyzed long-term (23 years) data of inorganic N deposition and loss for an extensive network of mature mixed hardwood covered
watersheds in the southern Appalachians of North Carolina to assess trends and dynamics of N in baseline ecosystems. We also assessed
watershed N saturation in the context of altered N cycles and stream inorganic responses associated with management practices and with
natural disturbances on reference watersheds. Reference watersheds were characterized as highly conservative of inorganic N with
deposition <9.0 kg ha-1 yr-1 and stream water exports below 0.25 kg ha-1 yr-1. However, reference watersheds appeared to be in a
transition phase between stage 0 and stage 1 of watershed N saturation as evidenced by significant time trend increases in annual flowweighted concentrations of NO3- in stream water and increases in the seasonal amplitude and duration of NO 3 concentrations during
1972-1994. These stream water chemistry trends were partially attributed to significant increases in NO 3- and NH4+ concentrations in
bulk precipitation over the same period and/or reduced biological demand due to forest maturation. Levels and annual patterns of stream
NO3- concentrations and intra-annual seasonal patterns characteristic of latter phases of stages 1 and 2 of watershed N saturation were
found for low-elevation and high-elevation clear-cut watersheds, respectively, and were related to the dynamics of microbial
transformations of N and vegetation uptake. Evidence for stage 3 of N saturation, where the watershed is a net source of N rather than a
N sink, was found for the most distributed watershed at Coweeta (hardwood converted to grass, fertilized, limed, treated with herbicide,
and subsequently characterized by successional vegetation). Compared to other intensive management practices, prescribed burning had
little effect on stream water NO3- concentrations, and stream NO3- losses associated with natural disturbances are small and short-lived.
328. Swift, Lloyd W., Jr.; Burns, Richard G. 1999. The three R's of roads: redesign, reconstruction, and restoration. Journal of
Forestry. 97(8): 40-44.
All too often, unpaved forest access roads in the southern Appalachian Mountains were located near streams and rivers, thereby
contributing storm flow and sediment to the aquatic ecosystem. Landowners and managers may not have the resources to reconstruct and
relocate all these roads to protect water quality. However, simple techniques for redesign of storm water drainage structures can provide
low-cost alternatives where the forest floor can absorb and filter runoff from roads.
329. Swift, Lloyd W., Jr.; Clinton, Patsy P. 1997. Stream temperature climate in a set of southern Appalachian streams. In: First
Biennial North American Forest Ecology Workshop: 1997 June 24-26: Raleigh, NC: 316-335.
Water temperature patterns are described for five streams on forested watersheds in western North Carolina as part of stream monitoring
in Wine Spring Ecosystem Management Area. Elevation ranged from 918 m at Nantahala Lake to 1660 m at Wine Spring Bald with four
temperature measurements sites located between 1145 m and 1200 m elevation, and one site at 925 m. Summer daily maximums were
relatively constant, 13 to 16o C; whereas, winter minimums ranged from 1 to 8o C. These streams are subjected to a daily temperature
range of 0 to 1o C in the summer, 1 to 2o C in the summer, 1 to 2o C in the fall, 1 to 3o C winter, and 1 to 5o C in the spring. Summer
precipitation events did not always appear to affect stream temperatures but winter storms may have raised daily minimum temperatures.
Water temperature responded to major fluctuations in air temperature and solar radiation more consistently than to precipitation input. In
winter, stream temperatures increased an average of 0.3o C with decreasing elevation from 1200 m to 1145 m. In late summer and fall,
stream temperatures increased by 1.2o C as elevation decreased from 1145 m to 925 m. However, in winter, the larger stream at 925 m
was as cold as the smaller stream at 1200 m. From November through April, water temperatures in one branch of the stream system,
draining a south-facing slope with shallow soils, were 0.6 to 1.5o C warmer than those in an adjacent stream at the same elevation.
330. Swift, Lloyd W., Jr.; Flexner, Morris; Burns, Richard; Melville, Bill. 1996. Impacts of human activities. In: Southern
Appalachian Man and the Biosphere (SAMAB). The Southern Appalachian Assessment Aquatics Technical Report. Report 2 of 5.
Atlanta, GA.: U.S. Department of Agriculture, Forest Service, Southern Region: 89-120. Chapter 5.
The charter of the Southern Appalachian Assessment was to assemble and analyze available information to answer questions about the
status and trends of resources in this ecologically complex region. The Assessment was a multiagency effort, sponsored by the Southern
Appalachian Man and the Biosphere Cooperative. The question for Chapter 5 of the Aquatic Technical Report was: "What are the
79
current and potential effects on Aquatic Resources from various activities?" Data assembled by EPA and Forest Service show that land
use choices have altered the regions hydrology and water quality. Natural disasters and human activities impact aquatic resources
through changes to the hydrology of streams and watersheds and by nonpoint and point source pollution. Maps display locations of
landfills, hazardous waste sites, mining activity, industrial and municipal outfalls and fish consumption advisories. Over 60 percent of
reported water quality impacts are due to nonpoint sources such as agriculture, forestry, and roads. For a majority of counties less than
30 percent of land is in agriculture uses. Maps display estimated soil erosion, pesticides use, and nitrogen loading from agricultural
activities. Land disturbance associated with urbanization, such as road locations in the riparian zone, is predicted to increase with
population growth in the region. A map shows estimated capital investment needs for future water treatment facilities.
331. Swift, Lloyd W., Jr.; Ledford, Elizabeth S. 1994. Where is bankfull in small southern Appalachian stream channels? In:
Riparian ecosystems in the humid U.S.: Functions, values and management; 1993 March 15-18; Atlanta, GA. Washington, DC: National
Association of Conservation Districts: 306-311.
The identification of bankfull width and bankfull depth is an important first step in some stream classification systems (e.g., Rosgen's).
However, past application of traditional criteria to define bankfull for Appalachian streams has yielded questionable results. Ten gaged
streams in the Nantahala Mountains of Western North Carolina were surveyed to identify apparent bankfull depth near each gaging site.
Estimated bankfull discharge was calculated for the measured cross-sections and compared with estimates of bankfull discharge derived
from annual peak flow distributions based on the record at each weir. On these streams, the maintenance of channel morphology by
bankfull flow appears to be a function of both the magnitude of high flow and the duration of that flow. A subset of field criteria for
identifying the bankfull depth on the channel wall was found to produce the most consistent results for Appalachian Mountain streams.
332. Tank, Jennifer L.; Meyer, Judy L.; Sanzone, Diane M.; Mulholland, Patrick J.; Webster, Jackson, R.; Peterson, Bruce J.;
Wollheim, Wilfred M.; Leonard, Norman E. 2000. Analysis of nitrogen cycling in a forest stream during autumn using a 15N-tracer
addition. Limnology Oceanography. 45(5): 1013-1029.
We added 15NH4C1 over 6 weeks to Upper Ball Creek, a second-order deciduous forest stream in the Appalachian Mountains, to follow
the uptake, spiraling, and fate of nitrogen in a stream food web during autumn. A priori predictions of N flow and retention were made
using a simple food web mass balance model. Values of δ15N were determined for stream water ammonium, nitrate, dissolved organic
nitrogen, and various compartments of the food web over time and distance and then compared to model predictions. Ammonium uptake
lengths were shortest at the beginning of the tracer addition (28 m) and increased through time (day 20 = 82 m, day 41 = 94m), and
ammonium residence time in stream water ranged from 4 min on day 0 to 15 min on day 41. Whole-stream ammonium uptake rates,
determined from the decline in 15NH4 in water over the stream reach, decreased from 191 mg N m-2 d –1 on day 0 to 83.2 mg N m-2 d –2 on
day 41. Temporal trends in the NH4 mass transfer coefficient (vf) were similar to uptake rates; vf was highest on day 0 (7.4) X 10-4 m s –1)
and lower on days 20 and 41 (2.7 and 2.8 X 10-4 m s-1, respectively). Rates of nitrification were estimated to be very low throughout the
tracer addition and accounted for < 3% of 15NH4 uptake on day 0. It appears that most of the N in epilithon was actively cycling based on
comparisons of 15N in stream water and biomass at the end of the experiment. In contrast, for allochthonous organic matter, we found
that microbial 15N represented 69% of the label in wood, 20% in leaves, and 31% in fine benthic organic matter (FBOM). Despite higher
δ15N values in primary producers, 15NH4 uptake rates per unit stream bottom area were generally lower in epilithon compared to the
detrital compartments, a result of the lower biomass of epilithon. Turnover times were similar for epilithon (47 d), leaves (38 d), and
FBOM (53 d) based on the decline in 15N tracer over the first 28 d after the addition stopped. Incorporation of 15N varied among biomass
compartments involved in ammonium uptake from water. Primary producers were more highly labeled than allochthonous organic
matter. Epilithon δ 15N values were higher than leaves or FBOM, appeared to reach isotopic equilibrium by day 42, and followed modelpredicted trends. The grazing mayfly Stenonema was more highly labeled than the epilithon. Leaves had very low 15 δN values, and δ 15N
values for the shredding stonefly Tallaperla were close to model predictions and followed labeling in leaves. Total retention of 15N, with
leaves and FBOM representing the largest portions. Export of 15N by suspended particulate and dissolved N accounted for an additional
11% and 30% of added 15N, respectively. Results from the 15N-tracer addition in Upper Ball Creek demonstrate the high ammonium
demand associated with microbes colonizing leaf detritus and the resultant linkage to invertebrate shredders. In Upper Ball Creek in
autumn, spiraling of NH4 is very tight, NH4 residence time in water is short, and uptake rates are very high. Analyses of N spiraling in
unimpacted streams provide an ecological foundation for assessment of spiraling in high-N streams.
333. Tank, Jennifer L.; Musson, John C. 1993. An inexpensive chamber apparatus for multiple measurements of dissolved oxygen
uptake or release. Journal of the North American Benthological Society. 12(4): 406-409.
An inexpensive, multi-channel signal conditioner was designed for the automated measurement of dissolved oxygen concentration in up
to six chambers. The apparatus has been used successfully to measure in situ photosynthesis and respiration rates of microbial
populations on substrate from streams at Coweeta Hydrologic Laboratory.
334. Tank, Jennifer L.; Webster, J.R. 1998. Interaction of substrate and nutrient availability on wood biofilm processes in streams.
Ecology. 79(6): 2168-2179.
We examined the effect of decomposing leaf litter and dissolved inorganic nutrients on the heterotrophic biofilm of submerged wood in
streams with and without leaves. Leaf litter was excluded from one headwater stream in August 1993 at Coweeta Hydrologic Laboratory
80
in the southern Appalachian Mountains. We compared microbial processes on wood in the litter-excluded stream to a reference stream
using microbial respiration, fungal biomass, and extracellular enzyme activity. Exclusion of leaf litter enhanced microbial respiration and
extracellular enzyme activity, and fungal biomass was seven times higher than in the reference stream. Nutrient-releasing substrates
placed beneath wood veneers indicated colimitation by nitrogen and phosphorus on biofilms in the reference stream. Our conclusion is
that, in the absence of nutrient immobilization by leaves, nutrients are more available for other heterotrophic processes. Nutrient
limitation may have been responsible for low microbial respiration, fungal biomass, and extracellular enzyme activity on wood in the
reference stream containing leaves. Our results suggest that competition for nutrients may regulate heterotrophic microbial processes in
these streams.
335. Tank, Jennifer L.; Webster, J.R.; Benfield, E.F.; Sinsabaugh, Robert L. 1998. Effect of leaf litter exclusion on microbial
enzyme activity associated with wood biofilms in streams. Journal of the North American Benthological Society. 17(1): 95-103.
Leaf litter inputs have been excluded from 1 of 2 1 st.-order streams at Coweeta Hydrologic Laboratory, North Carolina since August
1993 to examine the bottom-up effects of resource reduction on stream ecosystems. As part of the larger project, we studied the effect of
litter exclusion on the extracellular enzyme activity and fungal biomass of wood biofilms in the presence and absence of leaf litter.
Replicate strips of wood veneer were incubated in both streams for 28, 58, and 86 d. Ergosterol content (to estimate fungal biomass), the
activity of 5 lignocellulose-degrading enzymes, acid phosphates activity, breakdown rates, and % organic matter were determined when
the veneer strips were collected. Hydrolytic enzyme activity and wood breakdown rates in the litter-excluded stream were significantly
higher than in the reference stream. Enzyme activities of all hydrolytic enzymes were highly correlated with each other. Measurement of
relative activities of selected extra-cellular enzymes comparing carbon and nutrient acquisition suggested nutrient limitation of
heterotrophic biofilms in the reference stream. Microbial activity of wood biofilms was significantly altered by the exclusion of leaf
litter, and hydrolytic enzyme activity, as an indicator of carbon cycling, was higher on wood in streams without leaf litter.
336. Thompson, Andrew R.; Petty, J. Todd; Grossman, Gary D. 2001. Multi-scale effects of resource patchiness on foraging
behavior and habitat use by longnose dace, Rhinichthys cataractae. Freshwater Biology. 46: 145-160.
We examined the response of a predatory benthic fish, the longnose dace (Rhinichthys cataractae), to patchiness in the distribution of
benthic macroinvertebrates on cobbles at three hierarchical spatial scales during summer and autumn 1996, and spring 1997 in a southern
Appalachian stream. At the primary scale (four to five individual cobbles separated by < 1 m), the intensity of foraging was not
correlated with the biomass of benthic macroinvertebrates/cobble, regardless of season. At the secondary scale (i.e. foraging patches < 5
m in diameter), we found that benthic macroinvertebrates were patchily distributed in summer, but not in autumn or spring.
Concomitantly, in summer, longnose dace foraged on cobbles with a significantly higher biomass of benthic macrovertebrates than
nearby randomly selected cobbles with similar physical conditions (i.e. longnose dace tended to avoid low-prey foraging patches). In
contrast, when benthic macroinvertebrates were distributed homogeneously (spring and autumn), dace did not select patches with a
significantly higher biomass of benthic macroinvertebrates than that available on randomly selected cobbles. At the tertiary scale (i.e.
stream reaches 11-19 m long), the biomass of benthic macroinvertebrates (per cobble per reach) was patchily distributed (i.e. differed
significantly among reaches) in all seasons. Among reaches with physical characteristics preferred by longnose dace, (i.e. erosional
reaches dominated by cobble/boulder substratum and high current velocity), we detected a significant, positive correlation between the
biomass of biomass of benthic macroinvertebrates/cobble and longnose dace density in all seasons. Our results demonstrated that both
spatial and temporal patchiness in resource availability influenced significantly the use of both foraging patches and stream reaches by
longnose dace.
337. Tian, Guanglong; Vose, James M.; Coleman, David C.; Geron, Christopher D.; Walker, John T. 2004. Evaluation of the
effectiveness of riparian zone restoration in the southern Appalachians by assissing soil microbial populations. Applied Soil Ecology.
26:63-68.
Microbial biomass, nitrifiers and denitrifiers in surface soil (0-10 cm) were quantified in a riparian zone restoration project at Coweeta,
North Carolina, USA. Four treatments are included in this study: (1) a degraded (+N) riparian zone with continued compaction,
vegetation removal, and nutrient addition (mow and roll only and nutrient addition); (2) a degraded (-N) riparian zone with continued
compaction and vegetation removal, but without nutrient addition (mow and roll only); (3) a restored riparian area (no grazing, cessation
of manure and N fertilizer application and re-vegetation with natural regrowth for 2 years); and (4) reference riparian zone (no riparian
zone degradation has occurred within the last 10 years). Mean microbial biomass C increased from winter (316 mg kg -1) to summer (593
mg kg -1), and decreased from summer to fall (265 mg kg -1). There were no significant changes in microbial biomass C with the
cessation of manure and chemical fertilizer application in the degraded – N plot and with re-vegetation in the restored plot as compared
to the degraded + N plot. Microbial biomass C level in the restored plot was comparable to that in the reference plot for most seasons.
Restored plots had significant greater populations of denitrifiers than reference plots in the spring. Nitrifier numbers were lower in the
degraded – N and restored plots than the degraded + N. Ammonium oxidizers in summer were more abundant (25,000 g -1 soil) in the
degraded + N plot compared to (1000 g -1 soil) in the –N and restored plots, and NO2- oxidizers in the same period were more abundant
(130,000 g-1 soil) in the degraded + N plot than that in the degraded –N and restored plots about (40,000 g-1 soil). The soil NO3concentrations were considerably lower in the degraded –N and restored plots than the degraded + N plot. Our results imply either
cessation of manure and N fertilizer application or cessation of manure and N fertilizer and re-vegetation could contribute to restoration
of degraded riparian zone through reducing numbers of nitrifiers.
81
338. Tilley, David Rogers; Swank, Wayne T. 2003. EMERGY-based environmental systems assessment of a multi-purpose
temperate mixed-forest watershed of the southern Appalachian Mountains, USA. Journal of Environmental Management. 69: 213-227.
Emergy (with an 'm') synthesis was used to assess the balance between nature and humanity and the equity among forest outcomes of a
US Forest Service ecosystem management demonstration project on the Wine Spring Creek watershed, a high-elevation (1600 m),
temperate forest located in the southern Appalachian mountains of North Carolina, USA. EM embraces a holistic perspective, accounting
for the multiple temporal and spatial scales of forest processes and public interactions, to balance the ecological, economic, and social
demands placed on land resources. Emergy synthesis is a modeling tool that allows the structure and function of forest ecosystems to be
quantified in common units (solar emergy-joules, sej) for easy and meaningful comparison, determining 'system-value' for forcing
factors, components, and processes based on the amount of resources required to develop and sustain them, whether they are money,
material, energy, or information. The Environmental Loading Ratio (ELR), the units of solar emergy imported into the watershed via
human control per unit of indigenous, natural solar emergy, was determined to be 0.42, indicating that the load on the natural
environment was not ecologically damaging and that excess ecological capacity existed for increasing non-ecological activities (e.g.
timbering, recreation) to achieve an ELR of 1.0 (perfect ecological-economic balance). Three forest outcomes selected to represent the
three categories of desired sustainability (ecological, economic, and social) were evaluated in terms of their solar emergy flow to
measure outcome equity. Direct economic contribution was an order of magnitude less (224 x 10 12 solar emergy-joules (sej) ha-1) than
the ecological and social contributions, which were provided at annual rates of 3083 and 2102 x 1012 sej ha-1, respectively. Emergy
synthesis was demonstrated to holistically integrate and quantify the interconnections of a coupled nature-human system allowing the
goals of ecological balance and outcome equity to be measured quantitatively.
339. Turner, M.G.; Carpenter, S.R.; Gustafson, E.J. 1998. Land Use. In: Mac, M.J.; Opler, P.A.; Haeckler, Doran; Haeckler C.,
eds. Status and trends of the nation’s biological resources. U.S. Department o f the Interior, U.S. Geological Survey, Reston, VA. 1: 3761.
** No Abstract **
340. Turner, Monica G., Collins, Scott L.; Lugo, Ariel E., Magnuson, John J., Rupp, T. Scott, Swanson, Frederick. 2003.
Disturbance dynamics and ecological response: The contribution of long-term ecological research. BioScience. 53(1): 46-56.
Long-term ecological research is particularly valuable for understanding disturbance dynamics over long time periods and placing those
dynamics in a regional context. We highlighted three case studies from Long Term Ecological Research (LTER) Network sites that have
contributed to understanding the causes and consequences of disturbance in ecological systems. The LTER Network significantly
enhances the ability to study disturbance by (a) encompassing ecosystems subject to a wide range of disturbances, (b) providing a longterm baseline against which to detect change and measure ecosystem responses to disturbance, (c) permitting observation of slow or
infrequent events, (d) facilitating the use of multiple research approaches, (e) providing a focus for modeling disturbance dynamics, and
(f) contributing to land and resource management. Long-term research is crucial to understanding past, present, and future disturbance
dynamics, and the LTER Network is poised to make continuing contributions to the understanding of disturbance.
341. Turner, Monica G.; Pearson, Scott M.; Bolstad, Paul; Wear, David N. 2003. Effects of land-cover change on spatial pattern
of forest communities in the southern Appalachian mountains (USA). Landscape Ecology. 18: 449-464.
Understanding the implications of past, present and future patterns of human land use for biodiversity and ecosystem function is
increasingly important in landscape ecology. We examined effects of land-use change on four major forest communities of the Southern
Appalachian Mountains (USA), and addressed two questions: (1) Are forest communities differentially susceptible to loss and
fragmentation due to human land use? (2) Which forest communities are most likely to be affected by projected future land cover
changes? In four study landscapes, maps of forest cover for four time periods (1950, 1970, 1990, and projections for 2030) were
combined with maps of potential forest types to measure changes in the extent and spatial pattern of northern hardwoods, cove
hardwoods, mixed hardwoods, and oak-pine. Overall, forest cover increased and forest fragmentation declined in all four study areas
between 1950 and 1990. Among forest community types, cove hardwoods and oak-pine communities were most affected by land-cover
change. Relative to its potential, cove hardwoods occupied only 30-40% of its potential area in two study landscapes in the 1950s, and
oak-pine occupied ~50% of its potential area; cove hardwoods remained reduced in extent and number of patches in the 1990s. Changes
in northern hardwoods, which are restricted to high elevations and occur in small patches, were minimal. Mixed hardwoods were the
dominant and most highly connected forest community type, occupying between 47 and 70% of each study area. Projected land-cover
changes suggest ongoing reforestation in less populated regions but declining forest cover in rapidly developing areas. Building density
in forest habitats also increased during the study period and is projected to increase in the future; cove hardwoods and northern
hardwoods may be particularly vulnerable. Although increases in forest cover will provide additional habitat for native species, increases
in building density within forests may offset some of these gains. Species-rich cove hardwood communities are likely to be most
vulnerable to future land-use change.
342. Van Lear, D.H.; Vandermast, D.B.; Rivers, C.T.; Baker, T.T.; Hedman, C.W.; Clinton, B.D.; Waldrop, T.A. 2002.
American chestnut, rhododendron, ant the future of Appalachian cove forests. In: Outcalt, Kenneth W., ed; 2001, March 20-22;
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Knoxville, TN. Proceedings of the eleventh biennial southern silvicultural research conference. Gen. Tech. Rep. SRS-48. Asheville, NC:
U.S. Department of Agriculture, Forest Service, Southern Research Station. 214 p.
By the mid 1930’s, the southern Appalachians had been heavily cutover and the dominant hardwood, American chestnut (Castanea
dentate), had succumbed to the chestnut blight (Cryphonectria parasitica). Forests that had been burned on a frequent basis for millennia
were now protected and fire was excluded in large degree. We estimated that pre-blight importance of chestnut in cove forests and the
recovery of the overstory canopy on these rich sites following the blight and logging early in the last century. The overstory has largely
recovered from the blight, although chestnut is no longer a functional component of the cove forest ecosystem. Following the blight, the
successional pathway on two unlogged, old-growth sites proceeded to an oak association; on two logged sites, succession proceeded to
mesophytic forests. A gradual change in the understory has occurred in many coves that threatens their future diversity and productivity.
Encroaching rhododendron (Rhododendron maximum) thickets are severely inhibiting hardwood regeneration and reducing
herbaceous/shrub species richness. Neither shade-tolerant nor shade-intolerant hardwood species are becoming established in canopygaps where rhododendron is present in moderate to high densities. Rhododendron has become an ecologically dominant species because
it thrives on disturbance and, once established, inhibits other species. New management techniques will have to be developed if diversity
and productivity of cove hardwood forests are to be sustained.
343. Van Lear, David H. 1996. Dynamics of coarse woody debris in southern forest ecosystems. In: McMinn, James W.; Crossley,
D.A., Jr., ed. Biodiversity and coarse woody debris in southern forests: Proceedings of the workshop on coarse woody debris in southern
forests: effects on biodiversity; 1993 October 18-20; Athens, GA. Gen. Tech. Rep. SE-94. Asheville, NC: U.S. Department of
Agriculture, Forest Service, Southern Research Station: 10-17.
Coarse woody debris (CWD) standing dead trees, fallen trees, and decomposing large roots serves a number of ecological functions.
CWD loadings are dynamic in response to inputs from tree breakage and mortality and to losses from decomposition and fire. Two very
different natural processes, gap-phase dynamics and major episodic disturbances, contribute to inputs, as well as forest management
activities. Decay and combustion, if complete, yield both CO2 and H2O. However, neither is usually complete, and the combustion
process leaves some rapidly altered CWD, whereas decay results in the gradual formation of humic substances. Current forest
management practices often contribute to low loadings of CWD in southern forests. Although some data provide the basis for very
general estimates, there is a paucity of knowledge in the South on almost every aspect of CWD dynamics and loading.
344. van Vliet, P.C.J.; Beare, M.H.; Coleman, D.C. 1995. Population dynamics and functional roles of Enchytraeidae (Oligochaeta)
in hardwood forest and agricultural ecosystems. In: Collins, H.P.; Robertson, G.P.; Klug, M.J., eds. The significance and regulation of
soil biodiversity. Netherlands: Kluwer Academic Publishers: 237-245.
Population dynamics of enchytraeids are described for 2 montane-forested watersheds in southwestern North Carolina (Coweeta) and an
agricultural site under conventional (CT) and no-tillage (NT) management in the northeastern Georgia piedmont (Horseshoe Bend,
HSB). Given that much of the taxonomy, ecology, and community structure of enchytraeids is poorly known, our objective was to
identify key "indicators" of enchytraeid community structure, which could be used, in this case, to better understand their role in soil
structure formation. Although population densities of enchytraeids were higher in the forested (Coweeta) than in the arable soils (HSB),
the average ash free dry weight per enchytraeid at HSB was nearly double that found at Coweeta. Based on these measurements and an
estimate of their gut transit time, we calculated that the enchytraeids at HSB transported 2180 g of soil per m2 per year compared to 443
and 393 g m-2 yr-1 for watershed 18 and 27, respectively at Coweeta. We therefore hypothesize that enchytraeids have a larger influence
on soil structure in agricultural fields that in-forested areas, in spite of lower population densities. The ash free dry weight and ash wt.
per enchytraeid may qualify as key "indicator" parameters of enchytraeid community structure, which helps to understand their
functional role in ecosystems, though more studies are called for.
345. Vandermast, D.B.; Van Lear, D.H.; Clinton, B.D. 2002. American chestnut as an allelopath in the southern Appalachians.
Forest Ecology and Management. 165: 173-181.
Prior to the chestnut blight (Cryphonectria parasitica), American chestnut (Castanea dentate (Marsh.) Borkh.) was the most common
overstory tree in eastern deciduous forests. Chestnut’s dominance has often been attributed to its resistance to fire and subsequent
propensity to sprout vigorously and grow rapidly. Its role as an allelopath has rarely been studied.
Allelopathic qualities of chestnut leaves were tested with five native co-occurring tree species: red maple (Acer rubrum), sugar maple
(A. saccharum), eastern white pine (Pinus strobus), eastern hemlock (Tsuga canadensis), yellow-popular (Liriodendron tulipifera), a
native shrub rosebay rhododendron (Rhododendron maximum), and a bioassay species lettuce (Lactuca sativa var. “black seeded
Simpson”). For each species, six replicate of 100 seeds each were stratified for 90 days in distilled water or chestnut leaf extract, then
germinated for 21 days. Six additional replicates of red maple, eastern hemlock, yellow-popular, and rhododendron were germinated
without stratification. Lettuce seed was not stratified. When germination percentage peaked, seeds were removed from the experiment
and radicle length was measured. Chestnut leaf extract lowered germination rates of extract-treated lettuce, stratified and unstratified
eastern hemlock, and unstratified rhododendron seeds. Radicles of extract-treated lettuce and unstratified rhododendron were
significantly shorter than radicles of water-treated seeds. In general, radicles of extract-treated seeds were thinner, broke more easily, and
were less likely to have developed secondary roots than radicles of water-treated seeds. This study suggests leachate from American
chestnut leaf litter could have suppressed germination and growth of competing shrub and tree species and that allelopathy was a
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mechanism whereby American chestnut may have controlled vegetative composition and dominated eastern forests. Current vegetative
composition in southern Appalachian forests may be attributable, in part, to the disappearance of American chestnut as an allelopathic
influence.
346. Velbel, Michael Anthony. 1995. Interaction of ecosystem processes and weathering processes. In: Trudgill, Stephen T., ed.
Solute modeling in catchment systems. New York, NY: John Wiley & Sons Ltd: 193-209. Chapter 7.
This chapter explores the elemental exchange between botanical and inorganic compartments of small-forested catchments and the
consequences for geochemical mass balance of small catchments. The geochemical mass balance approach is used by geochemists and
ecologists. However, geochemical studies commonly ignore biological effects and ecological studies commonly oversimplify inorganic
geochemical processes. For the few ecosystems that have been studied in detail, the two approaches gave surprisingly consistent
quantitative results. This chapter (a) reviews previous work on biomass-inclusive mass balance calculations in the southern Appalachian
Mountains (b) examines the sensitivity of previous results to variations in assumed biomass composition and (c) extends the biomassinclusive mass balance approach to other forested catchments in the southern and central Appalachian Mountains for which biomass
effects have not been previously incorporated into geochemical mass balance calculations of weathering rates.
347. Vose, J.M.; Clinton, B.D.; Swank, W.T. 1994. Fire, drought, and forest management influences on pine/hardwood ecosystems
in the southern Appalachians. In: Fire and forest meteorology: proceedings of the 12th international conference on fire and forest
meteorology; 1993 October 26-28; Jekyll Island, GA. Bethesda, MD: Society of American Foresters Publication. 94-02: 232-240.
Establishment and maintenance of pitch pine/hardwood ecosystems in the Southern Appalachians depends on intense wildfire. These
ecosystems typically have a substantial evergreen shrub component (Kalmia latifolia), which limits regeneration of future overstory
species. Wildfires provide micro site conditions conducive to pine regeneration and reduce Kalmia competition. Recent droughts in the
region have resulted in significant acreages of southern pine beetle killed pine/hardwood stands. Site conditions are amenable to the high
intensity fires needed to regenerate pine; however, fire suppression limits the role of wildfire in these ecosystems. Research shows that
pines will not regenerate in the absence of severe disturbance, such as a high intensity fire, and mixed pine/hardwood ecosystem will not
be maintained. Currently, some of these ecosystems are being slashed, burned, and planted with white pine (Pinus strobus) in an effort to
restore site productivity. Our findings show that high intensity prescribed burning results in substantial pine regeneration and re-creation
of mixed pine/hardwood ecosystems.
348. Vose, J.M.; Elliott, K.J.; Johnson, D.W. 1995. Soil C02 flux in response to elevated atmospheric C02 and nitrogen fertilization:
patterns and methods. In: Lal, R.; Kimble, John; Levine, Elissa; Stewart, B.A., eds. Advances in soil science: soils and global change.
Boca Raton, FL: CRC Press, Inc., Lewis Publishers: 199-208. Chapter 16.
In this study, we quantified soil CO2 flux from soils growing ponderosa pine (Pinus ponderosa L.) under conditions of elevated
atmospheric CO2 and soil nitrogen. The objectives of this study were to: (1) quantify diurnal patterns in soil CO 2 evolution using a
dynamic, IRGA based measurement system, (2) examine the impacts of elevated atmospheric CO 2 and nitrogen fertilization on soil CO2
evolution, and (3) compare estimates using the IRGA based system with pCO 2 measurements. Open top chambers were used to elevate
CO2 concentration. The design consisted of three levels of nitrogen (ambient, 10, and 20 g m-2 yr-1 as ammonium nitrate, applied in early
spring) and four continuous CO2 treatments (ambient, no chamber; ambient chamber; +175 ppm; and +350 ppm). At the time of
sampling, seedlings had been grown in the chambers under treated conditions for two years. Soil were irrigated weekly with sufficient
water to maintain soil water potential at > -0.07 MPa. Most of the variation in diurnal soil CO2 flux corresponded to diurnal variation in
soil temperature. From these patterns, it is clear that methods, which sample only a portion of this diurnal period, may produce
misleading results, particularly if data are extrapolated temporally. Although there was substantial variation in average daily fluxes (e.g.,
flux rates varied from 7 to 15 g CO2 m-2 day-1), integrated values of soil CO2 flux were not significantly different among treatments.
Fluxes were greatest for the midlevel CO2 treatment (+175 ppm), which was the treatment with the greatest root biomass. Our fluxes
were comparable to studies where continuous IRGA systems were used, but substantially greater than studies using static techniques. In
addition, we found that pCO2 flux estimates were two to three times greater than IRGA based estimates.
349. Vose, J.M.; Harvey, G.J.; Elliott, E.J.; Clinton, B.D. 2003. Measuring and modeling tree and stand level transpiration. In:
McCutcheon, Steven C.; Schnoor, Jerald L. editors. Phytoremediation transformation and control of contaminants. Hoboken, New
Jersey. John Wiley & Sons, Inc.; 263-282; Chapter 8.
Transpiration is a key process in the application of phytoremediation to soil or groundwater pollutants. To be successful, vegetation must
transpire enough water from the soil or groundwater to control or take up the contaminant. Transpiration is driven by a combination of
abiotic (climate, soil water availability, and groundwater depth) and biotic (leaf area, stomatal functions, root amount and distribution,
and hydraulic characteristics) that need to be evaluated when considering appropriate site and species combinations. The protocols are
not trivial, but transpiration can be measured at a variety of scales using techniques such as direct measurements of sap flow on
individual trees, eddy flux gradient analyses, or gauged watersheds. Alternatively, models can be used to estimate transpiration, but these
usually require on-site calibration or parameterization to produce accurate predictions. Case study analyses across a range of site
conditions and species indicate a maximum transpiration capacity of approximately 7.5 x 10 6 liters of water per hectare per year (8 x 105
gallons of water per acre per year), with a range of 1.5 x 10 6 to 7.5 x 106 liters per hectare per year (1.6 x 105 to 8 x 105 gallons per acre
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year). Variation among sites is related to species, tree size, and stocking (i.e. vegetation density) differences. Application of a
physiologically based and site-specific parameterized model suggests reasonable agreement between measured and predicted
transpiration estimates for the Air Force Plant 4 site in central Texas.
350. Vose, James M. 1994. Effects of prescribed burning on ecosystem processes and attributes in pine/hardwood forests of the
southern Appalachians. In: Opportunities for the hardwood industry to address environmental challenges: Proceedings of the twentysecond annual hardwood symposium; 1994 May 12-15; Cashiers, NC. Blacksburg, VA: U.S. Department of Agriculture, Forest Service,
Southeastern Forest Experiment Station, Primary Hardwood Processing and Products Work Unit: 81-90.
Pine-hardwood ecosystems in the southern Appalachians are in a serious state of decline due to the combined effects of fire exclusion,
abusive land practices, and drought related insect infestations. A silvicultural treatment termed "fell and burn" is applied as a best
management practice (BMP) in an attempt to restore the diversity and productivity of these ecosystems. A multi-investigator study was
initiated to assess the effects of this treatment on ecosystem processes and attributes. Results showed that felling and burning had
positive effects on vegetation diversity and nitrogen (N) cycling, while soil erosion rates were unchanged. Losses in total aboveground N
pools were larger than observed with other silvicultural practices (e.g., stem only and whole tree harvest) due to the consumption of
foliage and forest floor. A more complete assessment will require a long-term approach where potential N additions from N-fixation and
other sources are quantified.
351. Vose, James M. 2000. Perspectives on using prescribed fire to achieve desired ecosystem conditions. In: Moser, W. Keith;
Moser, Cynthia F., eds. Fire and forest ecology: innovative silviculture & vegetation management. Proceedings Tall Timbers Fire
Ecology Conference; 1998 April 14-16; Tallahassee, Fl., No. 21:12-17.
Fire is a potentially powerful tool for achieving desired conditions of forest ecosystems. From an ecological perspective, the use of fire
requires affirmative answers to either of the following questions: (1) Does it increase ecosystem health and sustainability: and (2) Does it
preserve or restore unique species or habitats? Health and sustainability can be measured and defined in terms of: (1) rates and pool size
of water, carbon, and nutrient cycling, (2) resistance and resilience to low-intensity and –severity disturbance, and (3) minimizing the
likelihood of catastrophic disturbances. The departure of current ecosystem conditions from desired ecosystem conditions (defined by
structural and functional characteristics) depends on the history of land use and disturbance. The disturbance history also influences the
rate of attainment of desired conditions and the magnitude of ecosystem process response to burning. Hence, from an ecosystem
perspective, managers must understand the interactions among land use history, current conditions, and desired conditions. These issues
are examined using a case study for using prescribed fires in the southern Appalachian Mountains.
352. Vose, James M.; Bolstad, Paul V. 1999. Challenges to modeling NPP in diverse eastern deciduous forests: species-level
comparisons of foliar respiration response to temperature and nitrogen. Ecological Modeling. 122: 165-174.
Modeling net primary production (NPP) in eastern deciduous forests has usually been conducted with coarse scale models that lump or
simplify physiological processes. Foliar respiration (Rd) is a physiological process in forest ecosystem C cycling; however, there are very
few data on leaf respiration (Rd) for deciduous hardwood species. As a result, leaf Rd is one of the most superficially treated processes in
NPP models. We hypothesize that these data are critical for understanding patterns of net primary production and for parameter zing C
cycling models in diverse eastern deciduous hardwood forests. Our objectives were: (1) to determine differences in leaf R d for seven
hardwood species (Acer rubrum, Liriodendron tulipifera, Quercus alba, Quercus coccinea, Quercus rubra, Quercus prinus and Carya
glabra) common to the canopy of southern Appalachian forests; and (2) to evaluate the effects of using “lumped parameter” versus
“species-specific parameter’ approaches to determining the leaf respiration component of NPP. We used a temperature-controlled
cuvette and an infrared gas analyzer to develop temperature response curves during the night (24:00-0:600 h). Differences in leaf
respiration rates (expressed on either a mass or area basis) among species were substantial, varying by greater than three-fold at high leaf
temperatures (30°C). Q10 values ranged from 1.97 to 2.44. Some of the variation in leaf respiration rates among species was related to
differences in leaf N. Comparison wit a lumped parameter model of leaf respiration (PnET-II) indicated good agreement on average due
primarily to combinations of species, which resulted in compensating errors; however, there was the potential for considerable variation
with different mixes of species.
353. Vose, James M.; Clinton, Barton D.; Emrick, Verl. 1995. Forest floor C02 flux from two contrasting ecosystems in the
southern Appalachians. In: Gottschalk, Kurt W.; Fosbroke, Sandra L.C., eds. Proceedings, 10th Central Hardwood Forest Conference;
1995 March 5-8; Morgantown, WV. General Technical Report NE-197. Randor, PA: U.S. Department of Agriculture, Forest Service,
Northeastern Forest Experiment Station. 165-171.
We measured forest floor C02 flux in two contrasting ecosystems (white pine plantation and northern hardwood ecosystems at low and
high elevations, respectively) in May and September 1993 to quantify differences and determine factors regulating C0 2 fluxes. An
automated, IRGA based, flow through system was used with chambers inserted into the soil. This approach allowed quantification of
diurnal flux patterns, which were subsequently averaged to estimate daily mean flux rates (mmol m-2s-1). Mean flux rates were 60
percent greater in the white pine ecosystem (8.9 mmole m-2 s-1) than in the northern hardwood ecosystem (5.6 mmole m-2 s-1). Across
ecosystems and sample dates, the most important regulating factor was soil temperature (r -2=0.70; p<0.0001). Mean (24-hr) soil
temperature (at 5 cm depth) was 2.5\DEG C lower in the northern hardwood stand relative to the white pine stand. All other parameters
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considered (i.e., soil C: N, root mass, root C: N, litter C: N, litter mass) did not explain the differences in flux rates between sites, but
variation in fine root mass and litter C: N did explain spatial and temporal variation within the northern hardwood site. These results
indicated that a large spatial scale, variation in soil temperature was more important in regulating forest floor CO 2 flux than factors more
closely associated with the species composition and productivity of the sites (e.g., litter and root mass and quality).
354. Vose, James M.; Dougherty, Phillip M.; Long, James N.; Smith, Frederick W.; Gholz, Henry L.; Curran, Paul J. 1994.
Factors influencing the amount and distribution of leaf area of pine stands. Ecological Bulletins (Copenhagen). 43: 102-114.
Leaf area index (LAI) of forest ecosystems determines rates of energy and material exchange between plant canopies and the
atmosphere. Considerable variation exists in the value and timing of maximum LAI in pine stands. Maximum LAI (total) varied from 5
to 30 across a range of species and environments and this was reached 8 to 50 yrs after stand establishment. The variation in maximum
LAI was related to multiple factors including site quality (climate and soils) and shade tolerance. Timing differences appear to be related
to growth rates and stocking/stand density relationships. Rapid growth rates, well stocked stands, and warm climates result in the earliest
canopy closure. Nitrogen most commonly limits LAI, although water can limit LAI in arid environments. Other nutrients may also limit
LAI but have been less extensively studied. Seasonal dynamics vary considerably among pines and this is due to species dependent
differences in foliar longevity. Species with relatively few foliage age classes are the most dynamic seasonally and are most responsive
to environmental fluctuations. Among several pine species, vertical LAI distribution in closed canopies follows a normal distribution.
355. Vose, James M.; Elliott, Katherine J.; Johnson, Dale W.; Tingey, David T.; Johnson, Mark G. 1997. Soil respiration
response to three years of elevated CO2 and N fertilization in ponderosa pine (Pinus ponderosa Doug. ex Laws.) Plant and Soil. 190: 1928.
We measured growing season soil CO2 evolution under elevated atmospheric [CO2] and soil nitrogen (N) additions. Our objectives were
to determine treatment effects, quantify seasonal variation, and compare two measurement techniques. Elevated [CO 2] treatments were
applied in open-top chambers containing ponderosa pine seedlings. N applications were made annually in early spring. The experimental
design was a replicated factorial combination of CO2 and N. Soils were irrigated to maintain soil moisture at > 25 percent. Soil CO 2
evolution was measured over diurnal periods (20-22 hours) in October 1992, and April, June, and October 1993 and 1994 using a flowthrough, infrared gas analyzer measurement system and corresponding pCO 2 measurements were made with gas wells. Significantly
higher soil CO2 evolution was observed in the elevated CO2 treatments; N effects were not significant. Averaged across all measurement
periods, fluxes were 4.8, 8.0, and 6.5 for ambient + 175 CO 2, and +350 CO2 respectively. Treatment variation was linearly related to
fungal occurrence as observed in minirhizotron tubes. Seasonal variation in soil CO2 evolution was non-linearly related to soil
temperature; i.e., fluxes increased up to approximately soil temperature and decreased dramatically at temperatures > 18\DEG C. These
patterns indicate exceeding optimal temperatures for biological activity. The dynamic, flow-through measurement system was weakly
correlated with the pCO2 measurement method.
356. Vose, James M.; Elliott, Katherine J.; Johnson, Dale W.; Walker, Roger F.; Johnson, Mark G.; Tingey, David T. 1995.
Effects of elevated CO2 and N fertilization on soil respiration from ponderosa pins (Pinus ponderosa) in open-top chambers. Canadian
Journal of Forest Research. 25: 1243-1251.
We measured growing season soil CO2 evolution under elevated atmospheric CO2 and soil nitrogen (N) additions. Our objectives were to
determine treatment effects, quantify seasonal variation, and determine regulating mechanisms. Elevated CO 2 treatments were applied in
open-top chambers containing 3-year-old ponderosa pine (Pinus ponderosa Dougl. ex Laws.) seedlings. Nitrogen applications were
made annually in early spring. The experimental design was a replicated factorial combination of CO 2 and N. Soils were irrigated to
maintain soil moisture at >25%. Soil CO2 evolution was measured over diurnal periods in April, June, and October 1993 using a flowthrough, infrared gas analyzer measurement system. To examine regulating mechanisms, we linked our results with other studies
measuring root biomass with destructive sampling and root studies using minirhizotron techniques. Significantly higher soil CO2
evolution was observed in the elevated CO2 treatments in April and October; N effects were not significant. In October, integrated daily
values for CO2 evolution ranged from 3.73 to 15.68 g CO2·m-2·day-1 for the ambient CO2 + 0 N and 525 mL·L-1 CO2 + 20 g·m-2 N,
respectively. Soil CO2 flux among treatments was correlated with coarse root biomass, indicating that at least some of the variation
observed among treatments was related to variation in root respiration. Across all sample periods and treatments, there was a significant
correlation between soil CO2 evolution and percent fungal hyphae observed in minirhizotron tubes. Hence, some of the seasonal and
treatment variation was also related to differences in heterotrophic activity.
357. Vose, James, M.; Geron, Chris, B.; Lockaby, Graeme; Sverdrup, Harald; Raulund-Rasmussen, Karsten. 2002.
Restoration effects on biogeochemistry and aquatic systems. In: Proceedings of the IUFRO conference on restoration of boreal and
temperate forests. Documenting forest restoration knowledge and practices in boreal and temperate ecosystems. 2002 April 28- May 2;
Vejle, Denmark. Danish Centre for Forest, Landscape and Planning. 2002. ISBN#: 87-7903-140-4: 122-123.
Over the past several years, there has been an acceleration of restoration efforts to mitigate or enhance key components of watershed
ecosystems that regulate biogeochemical cycling and associated aquatic components. Nutrient budget components serve as a focal point
for identifying ecosystem nutrient pools or processes requiring restoration to enhance biogeochemical processes and aquatic systems.
Restoration of biogeochemical processes and aquatic systems is inherently scale dependent. The interrelationship between
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biogeochemical processes and aquatic systems of upland tributaries to higher order streams with a variety ecosystem conditions (e.g.
mixed ownership, mixed condition) must be understood in a cumulative effects context to develop appropriate restoration strategies.
Most importantly, a conceptual and analytical framework must be developed to assess thresholds of response and recovery at a variety of
spatial and temporal scales. The resistance and resilience model of ecosystem response to disturbance is one potential conceptual
framework for evaluating restoration success for enhancing biogeochemical cycles and aquatic systems. The model can be used as a
conceptual construct for evaluating spatial and temporal aspects of current ecosystem condition, desired ecosystem condition, and
systems response. While the resistance-resilience model provides the conceptual framework, analytical tools modeling, GIS, and remote
sensing- are required to quantify spatial and temporal responses.
358. Vose, James, M.; Maass, Jose’ Manuel. 1998. A comparative analysis of hydrologic responses of tropical deciduous and
temperate deciduous watershed ecosystems to climatic change. In: North American Science Symposium. Toward a unified framework
for inventorying and monitoring forest ecosystem resource. 1998 November 1-6; Guadalajara, Jalisco, Mexico. U.S. Department of
Agriculture Forest Service, Rocky Mountain Research State, 1999. Proceedings RMRS P-12; 292-298.
Long term monitoring of ecological and hydrological processes is critical to understanding ecosystem function and responses to
anthropogenic and natural disturbances. Much of the world’s knowledge of ecosystem responses to disturbance comes from long-term
studies on gaged watersheds. However, there are relatively few long-term sites due to the large cost and commitment required to
establish and maintain them. Knowledge gained from these sites is also important for predicting responses to future disturbances, such as
climatic change, and these sites should be the focal point for the development and validation of predictive models. In this study, we
apply a hydrologic model (PROSPER) using climate, vegetation, and soil parameters from watersheds in the mesic southeastern United
States and in the dry tropical forests of western Mexico to assess the overall effects of climate change (increased temperature and [CO2]
on watershed hydrology. We both found that evapotranspiration (ET) increased substantially in both ecosystem types, with increases
ranging from 24 to 42%. These increases were directly attributable to changes in leaf energy balance and evaporative demand.
Streamflow decreased more substantially, with virtually no streamflow under the greatest temperature increase scenario (+20%) at the
site in western Mexico. Decreased stomatal conductance was not sufficient to offset the effects of increased temperature.
359. Vose, James M.; Ryan, Michael G. 2002. Seasonal respiration of foliage, fine roots, and woody tissues in relation to growth,
tissue N, and photosynthesis. Global Change Biology. 8: 182-193.
Autotrophic respiration may regulate how ecosystem productivity responds to changes in temperature, atmospheric [CO 2], and N
deposition. Estimates of autotrophic respiration are difficult for forest ecosystems, because of the large amount of biomass, different
metabolic rates among tissues, and seasonal variation in respiration rates. We examined spatial and seasonal patterns in autotrophic
respiration in a Pinus strobus ecosystem, and hypothesized that seasonal patterns in respiration rates at a common temperature would
vary with [N] for fully expanded foliage and fine roots, with photosynthesis for foliage, and with growth for woody tissues (stems,
branches, and coarse roots). We also hypothesized that differences in [N] would largely explain differences in maintenance or dormantseason respiration among tissues. For April-November, mean respiration at 15°C varied from 1.5 to 2.8 µmol kg-1s-1 for fully expanded
foliage, 1.7-3.0 for growing foliage, 0.8-1.6 for fine roots, 0.6-1.1 (sapwood) for stems, 0.5-1.8 (sapwood) for coarse roots. Growing
season variation in respiration for foliage produced the prior year was strongly related to [N]. For current-year needles, respiration did
not covary with [N]. Night-time foliar respiration did not vary in concert with previous-day photosynthesis for either growing or fully
expanded needles. Stem growth explained about one-third of the seasonal variation in stem respiration (r2=0.38), and also variation
among trees (r2=0.43). We did not determine the cause of seasonal variation in branch and coarse root respiration, but it is unlikely to be
directly related to growth, as the pattern of respiration in coarse roots and branches was not synchronized with stem growth. Seasonal
variations in temperature-corrected respiration rates were not synchronized among tissues, except foliage and branches. Spatial
variability in dormant-season respiration rates was significantly related to tissue N content in foliage (r 2= 0.67), stems (r2 =0.45), coarse
roots (r2 =0.36), and all tissues combined (r2=0.83), but not for fine roots and branches. Pre unit N, rates for N, rates for P. strobus varied
from 0.22 to 3.4 µmol molN –1s-1 at 15°C, comparable to those found for other conifers. Accurate estimates of annual autotrophic
respiration should reflect seasonal and spatial variation in respiration rates of individual tissues.
360. Vose, James M.; Sullivan, Neal H.; Clinton, Barton D.; Bolstad, Paul V. 1995. Vertical leaf area distribution, light
transmittance, and application of the Beer-Lambert Law in four mature hardwood stands in the southern Appalachians. Canadian Journal
of Forest Research. 25: 1036-1043.
We quantified stand leaf area index and vertical leaf area distribution, and developed canopy extinction coefficients (k), in four mature
hardwood stands. Leaf area index, calculated from litter fall and specific leaf area (cm2.g-1), ranged from 4.3 to 5.4 m2.m-2. In three of
the four stands, leaf area was distributed in the upper canopy. In the other stand, leaf area was uniformly distributed throughout the
canopy. Variation in vertical leaf area distribution was related to size and density of upper and lower canopy trees. Light transmittance
through the canopies followed the Beer-Lambert Law, and k values ranged from 0.53 to 0.67. Application of these k values to an
independent set of five hardwood stands with validation data for light transmittance and litter-fall leaf area index yielded variable results.
For example, at k=0.53, calculated leaf area index was within ±10% of litter-fall estimates for three of the five sites, but from -35 to
+85% different for two other sites. Averaged across all validation sites, litter-fall leaf area index, and Beer-Lambert leaf area index
predications were in much closer agreement (±7 to ±15%).
87
361. Vose, James M.; Swank, Wayne T.; Clinton, Barton D.; Hendrick, Ronald L.; Major, Amy E. 1997. Using fire to restore
pine/hardwood ecosystems in the southern Appalachians of North Carolina. In: Greenlee, Jason M., ed. Proceedings: First conference on
fire effects on rare and endangered species and habitats. 1995 November. Coeur d'Alene, Idaho. Fairfield, WA. International Association
of Wildland Fire: 149-154.
Pine/hardwood communities on xeric sites in the southern Appalachians, although limited in extent, are unique vegetation types that
provide important habitat for both flora and fauna. The pine component of this system is in a serious state of decline due to a recent
severe drought and resultant widespread and severe southern pine beetle epidemic. These systems have historically regenerated
following intense natural fire but recent fire suppression efforts and the presence of mountain laurel (Kalmia latifolia L.), an evergreen
ericaceous shrub, have resulted in continued decline. The fell and burn method is a common silvicultural tool to increase the productivity
of these sites, but high costs and large nitrogen (K) losses have prompted examination of alternative treatments. One such alternative is
stand restoration burning, where intense fires are ignited intact stands. Our comparison of the fell and burn treatment versus the stand
restoration burning indicated that stand restoration burning produced stand conditions consistent with restoration objectives (e.g.,
increased pine regeneration), with substantially lower site N losses. Hence, where appropriate conditions exist, stand replacement
burning may be a preferred restoration technique.
362. Vose, James M.; Swank, Wayne T.; Clinton, Barton D.; Knoepp, Jennifer D.; Swift, Lloyd W. 1999. Using stand
replacement fires to restore southern Appalachian pine-hardwood ecosystems: effects on mass, carbon, and nutrient pools. Forest
Ecology and Management. 114: 215-226.
Pine-hardwood ecosystems in the southern Appalachians are in serious decline due to fire exclusion and insect infestations. Fire has been
advanced as a tool to restore these ecosystems, yet there are few studies evaluating overall ecosystem effects. Our objectives were to
evaluate the effects of stand restoration burning on forest floor nitrogen (N) and carbon (C) pools, and soil and stream chemistry. We
measured changes in forest floor mass, N, and C; changes in soil chemistry (calcium (Ca), potassium (K), magnesium (Mg), cation
exchange capacity (CEC), pH, C, and N); and changes in stream nitrate (NO3). Results showed that significant reductions in mass, N,
and C occurred only for litter and small wood on the ridge, where N losses were 52.9 kg ha -1 for litter and small wood combined. No
significant effects were observed on the mid- or lower slope of the treatment watershed. Losses on the ridge are considerably lower than
losses which occur with alternative burning treatments used in the region, such as the fell and burn treatment. Soil and stream chemistry
showed no response to burning. Spatial heterogeneity in fire intensity and severity associated with stand replacement burning results in a
mosaic of fire effects and considerably less consumption and subsequent nutrient losses.
363. Vose, James M.; Swank, Wayne T.; Geron, Chris D.; Major, Amy E. 1996. Emissions from forest burning in the
Southeastern U.S.: Application of a model determining spatial and temporal fire variation. In: Levine, J.S., ed. Biomass burning and
global change: Volume 2: Biomass burning in South America, Southeast Asia, and temperate and boreal ecosystems and the oil fires of
Kuwait. Cambridge, MA: MIT Press: 733-749. Chapter 68.
Significant quantities of forestland burn in the southeastern U.S. and emissions of particulates, ozone precursors, and radioactively
important gases (PM-10, CO, CO2, NOx NMOC, THC, N2O, and CH4) are an important concern. Accurate estimation of emissions
requires a modeling approach and we developed a model, which predicts emissions by state, province, month, and fire type. In addition,
the model accounted for the effects of spatial and temporal variation in fuel moisture (as driven by climatic conditions) on fuel
consumption, variation in the relative distribution of pine and hardwoods, and fie and fuel specific emissions factors. Variation in the
relative contribution of prescribed fire versus wildfire emissions varied by state. In Alabama, most emissions were from prescribed
burning in the coastal plain province. In contrast, nearly all emissions were from wildfire in North Carolina, Virginia, and Tennessee and
there was a uniform distribution among provinces. Temporal patterns varied by province. Peak emissions occurred in March for the
mountain province and in April in the piedmont and coastal plain provinces. In the piedmont and coastal plain, emissions remained
elevated through September. The primary factor influencing spatial and temporal variation in emissions was the number of hectares
burned.
364. Vose, James M.; Swank, Wayne T.; Harvey, Gregory J.; Clinton, Barton D.; Sobek, Christine. 2000. Leaf water relations
and sapflow in eastern cottonwood (Populus deltoides Bartr.) trees planted for phytoremediation of a groundwater pollutant.
International Journal of Phytoremediation. 2(1): 53-73.
Plants that remediate groundwater pollutants may offer a feasible alternative to the traditional and more expensive practices. Because its
success depends on water use, this approach requires a complete understanding of species-specific transpiration patterns. The objectives
of this study were (1) to quantify tree and stand-level transpiration in two age classes (whips and 1-year-old seedlings) of eastern
cottonwoods (Populus deltoides Bartr.), and (2) to determine climatic and physiological driving variables at the Carswell Air Force Base
in central Texas, USA. Trichloroethylene (TCE) was detected in shallow (2 to 3 m) groundwater in the early 1980s. Cottonwood whips
and 1-year-old potted seedlings were planted in two separate 0.15-ha plantations in spring 1996. Sapflow gauges determined sapflow on
14 to 16 trees in May, June, July, August, and October 1997. Without adjusting for differences in tree size, sapflow rates were greater for
1-year-old trees than ships (peak values were 0.75 and 0.53 kg hr-¹ tree-¹, respectively). When adjusted for tree size, the pattern reversed,
with whips having significantly greater sapflow rates than 1-year-old trees (peak values were 0.053 and 0.045 kg cm²hr¹, respectively).
Temporal variation (diurnal and seasonal) in sapflow rates was principally related to VPD, solar radiation, and leaf conductance.
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Extrapolating to the stand and across the growing season, the plantations transpired ~ 25 cm of water. Early attainment of high levels of
transpiration indicates that the stands will transpire considerably more water as leaf area and root exploitation increases with stand
development.
365. Vose, Jim. 2001. Forest carbon cycling. In: El-Shaarawi, Abdel H.; Piegorsch, Walter, W., eds. Encyclopedia of environmetrics
volume 2. John Wiley & Sons, Inc. Book Chapter. 806-808.
The terrestrial carbon (C) cycle comprises three components: C inputs, C outputs, and C pools. Worldwide, terrestrial ecosystems
contain approximately 2000 Pg C, most of which is in belowground pools (~1500 Pg C) {4). By contrast, the atmosphere contains ~750
Pg C. The nearly three-fold greater C in terrestrial ecosystems relative to the atmosphere means that terrestrial C cycling processes
potentially have a major influence on atmospheric carbon dioxide (CO2) at global scales, and hence on changes in atmospheric C0 2 and
climate. At the ecosystem scale, the net change in C pools, or net ecosystem production (NEP), includes heterotrophic processes in the
forest floor and soil component of the C cycle. C inputs to the forest floor and soil derive from inputs from mortality, leaf, and root
senescence and exudates from primary and secondary producers. C outputs from the forest floor and soil result from heterotrophic and
autotrophic respiration. Most of C derived from soil and forest floor respiration is released back to the atmosphere as CO2, while the
remainder dissolves and enters the aquatic system in streamflow or groundwater. Some soil and forest floor C0 2 is re-fixed by understory
and overstory vegetation, while the rest is recycled back to the atmosphere.
366. Vroblesky, Don A.; Clinton, Barton D.; Vose, James M.; Clifton, C. Casey; Harvey, Gregory J.; Bradley, Paul M. 2004.
Ground water chlorinated ethenes in tree trunks: case studies, influence of recharge, and potential degradation mechanism. Ground
Water Monitoring & Remediation. 24(3): 124-138.
Trichloroethene (TCE) was detected in cores of trees growing above TCE-contaminated ground at three sites: the Carswell
Golf Course in Texas, Air Force Plant PJKS in Colorado, and Naval Weapons Station Charleston in South Carolina. This was
true even when the depth to water was 7.9 m or when the contaminated aquifer was confined beneath ~3 m of clay. Additional
ground water contaminants detected in the tree cores were cis–1,2-dichloroethene at two sites and tetrachloroethene at one site.
Thus, tree coring can be a rapid and effective means of locating shallow subsurface chlorinated ethenes and possibly identifying
zones of active TCE dechlorination. Tree cores collected over time were useful in identifying the onset of ground water contamination.
Several factors affecting chlorinated ethene concentrations in tree cores were identified in this investigation. The
factors include ground water chlorinated ethene concentrations and depth to ground water contamination. In addition, differing
TCE concentrations around the trunk of some trees appear to be related to the roots deriving water from differing areas. Opportunistic
uptake of infiltrating rainfall can dilute prerain TCE concentrations in the trunk. TCE concentrations in core headspace
may differ among some tree species. In some trees, infestation of bacteria in decaying heartwood may provide a TCE dechlorination
mechanism within the trunk.
367. Waldrop, Thomas A.; Welch, Nicole Turrill; Brose, Patrick, H.; Elliott, Katherine, J.; Mohr, Helen, H.; Gray, Ellen, E.
2000. Current research on restoring ridge top pine communities with stand replacement fire. In: U.S.Department of Agriculture, Forest
Service, Northeastern Research Station GTR-NE-274: Proceedings Workshop on Fire, People, and the Central Hardwoods Landscape;
2000 March 12-14; Richmond, Kentucky: 103-109.
Ridge top pine communities of the Southern Appalachian Mountains historically have been maintained by lightning-and human-caused
fires. With fire suppression for several decades, characteristic stands are entering later seral stages. They typically have an overstory of
Table Mountain (Pinus pungens) and/or pitch pine (P. rigida). A midstory of chestnut oak (Quercus prinus), scarlet oak (Q. coccinea) and
black gum (Nyssa sylvatica), and a shrub layer of dense mountain laurel (Kalmia latifolia). Previous research suggests that restoration of
these communities can be accomplished with high-intensity fires that open the forest canopy and expose mineral soil. Three recent
studies examined plant-community response to high intensity prescribe fires. A series of corollary studies help to explain some of the
results of these field studies. High and medium-high intensity fires provided adequate sunlight for pine seedlings, whereas medium-low
and low intensity fires did not. Post-burn duff was deep and did not vary by fire intensity. We observed sufficient seedling densities to
restore pine-dominated stands after all but the highest intensity fires. Many seedlings survived the first growing season as their roots
penetrated duff to reach mineral soil. Hardwood rootstocks resprouted on sites treated with all fire intensities ad may out-compete pine
seedlings for available resources. High-intensity fires may have reduced mycorrhizal abundance and moisture availability for new
germinants. Fires of lower intensity than previously recommended or multiple fires of very low-intensity may best provide conditions for
pine regeneration, but additional research is needed.
368. Walker, John F.; Miller, Orson K., Jr.; Lei, Tom.; Semones, Shawn,; Nilsen, Erik.; Clinton, B.D. 1999. Suppression of
ectomycorrhizae on canopy tree seedlings in Rhododendron maximum L. (Ericaceae) thickets in the southern Appalachians. Mycorrhiza.
9: 49-56.
Thickets of Rhododendron maximum (Ericaceae) (Rm) in the southern Appalachians severely limit regeneration of hardwood and
coniferous seedlings. Experimental blocks were established in and out of Rm thickets in mature, mixed hardwood/conifer forest in
Macon County, N.C. Litter and organic layer substrates were removed, composited and redistributed among plots within the blocks
(except for control plots). Seedlings of northern red oak (Quercus rubra) and eastern hemlock (Tsuga canadensis) were planted in the
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plots and harvested at the end of the first and second growing seasons. Litter manipulation had no effect on total mycorrhizal
colonization, but the distribution of Cenococcum geophilum mycorrhizae was altered. After the first year, percent mycorrhizal
colonization of hemlocks not in Rm thickets (62%) was at least three times higher than in Rm thickets (19%), and the ramification index
(no. of mycorrhizae (cm-1) had increased by more than a factor of four (2.83 versus 0.61). In addition, colonization of 1-year-old
hemlocks by C geophilum was significantly higher within blocks with (10.4%) than without (4.6%) Rm. Differences in mycorrhizal
colonization, ramification indices and colonization by C. geophilum were absent or less pronounced on 2-year-old hemlocks and 1- and 2
year-old oak seedlings. The biomasses of first year oak roots and shoots and second year shoots were 50% less in Rm thickets.
Biomasses of first year hemlock roots and second year shoots were also reduced. Mycorrhizal parameters were correlated with some
growth parameters only for hemlock seedlings, but did not explain most of the variation observed.
369. Walker, John T.; Geron, Christopher D.; Vose, James M.; Swank, Wayne T. 2002. Nitrogen trace gas emissions from a
riparian ecosystem in southern Appalachia. Chemosphere. 49(10): 1389-1398.
In this paper, we present two years of seasonal nitric oxide (NO), ammonia (NH 3), and nitrous oxide (N2O) trace gas fluxes measured in
a recovering riparian zone with cattle excluded and adjacent riparian zone grazed by cattle. In the recovering riparian zone, average NO,
NH3, and N2O fluxes were 5.8, 2.0, and 76.7 ng N m(-2) s(-1) (1.83, 0.63, and 24.19 kg N ha-1 y-1), respectively. Fluxes in the grazed
riparian zone were larger, especially for NO and NH3, measuring 9.1, 4.3, and 77.6 ng N m-2 s-1 (2.87, 1.35, and 24.50 kg N ha-1 y-1) for
NO, NH3, and N2O, respectively. On average, N2O accounted for greater than 85% of total trace gas flux in both the recovering and
grazed riparian zones, though N2O fluxes were highly variable temporally. In the recovering riparian zone, variability in seasonal
average fluxes was explained by variability in soil nitrogen (N) concentrations. Nitric oxide flux was positively correlated with soil
ammonium (NH4+) concentration, while N2O flux was positively correlated with soil nitrate (NO3-) concentration. Ammonia flux was
positively correlated with the ratio of NH4+ to NO3-. In the grazed riparian zone, average NH3 and N2O fluxes were not correlated with
soil temperature, N concentrations, or moisture. This was likely due to high variability in soil microsite conditions related to cattle
effects such as compaction and N input. Nitric oxide flux in the grazed riparian zone was positively correlated with soil temperature and
NO3- concentration. Restoration appeared to significantly affect NO flux, which increased approximate to 600% during the first year
following restoration and decreased during the second year to levels encountered at the onset of restoration. By comparing the ratio of
total trace gas flux to soil N concentration, we show that the restored riparian zone is likely more efficient than the grazed riparian zone
at diverting upper-soil N from the receiving stream to the atmosphere. This is likely due to the recovery of microbiological communities
following changes in soil physical characteristics.
370. Wallace, J.B.; Eggert, S.L.; Meyer, J.L.; Webster, J.R. 1997. Multiple trophic levels of a forest stream linked to terrestrial
litter inputs. Science. 277: 102-104.
The importance of terrestrial-aquatic linkages was evaluated by a large-scale, 3-year exclusion of terrestrial leaf litter inputs to a forest
stream. Exclusion of leaf litter had a strong bottom-up effect that was propagated through detritivores to predators. Most invertebrate
taxa in the predominant habitat declined in either abundance, biomass, or both, compared with taxa in a nearby reference stream.
However, fauna in moss habitats changed little, indicating that different food webs exist in habitats of different geomorphology. Thus,
the ecosystem-level consequences of excluding detrital inputs to an ecosystem were demonstrated. Inputs of riparian detritus are
essential for conservation or restoration of diverse stream food webs.
371. Wallace, J.B.; Webster, J.R.; Eggert, S.L.; Meyer, J.L. 2000. Small wood dynamics in a headwater stream. Verhandlungen
International Vereinigung Limnology. 27: 1361-1365.
Wood influences a wide array of abiotic and biotic factors in streams (Harmon et al. 1986). Long –term estimates of export were
combined with a litter exclusion study (Wallace et al. 1997), and direct removal of all small wood ≤10-cm diameter to further reduce the
link between a forested headwater catchment and its stream (Wallace et al. 1999). This provided an excellent opportunity to address
several aspects of wood dynamics in a small headwater stream. These include: (1) woody debris standing crop; (2) adequacy of nondestructive woody debris sampling versus complete removal of all woody debris ≤10 cm diameter; and (3) annual measurements of
small woody debris input and losses.
372. Wallace, J. Bruce; Anderson, N.H. 1995. Habitat, life history, and behavioral adaptations of aquatic insects. In: Merritt,
Richard W.; Cummins, Kenneth W., eds. An Introduction to the aquatic insects of North America. Third edition. Dubuque, Iowa:
Kendall/Hunt Publishing Company: 41-73. Chapter 5.
Ecosystem-level studies often include the study of processing of organic matter by various groups of animals, and insects are frequently
the most abundant group considered. Unfortunately, the life histories of many aquatic insect species, particularly their immature stages,
remain unknown. Their diversity, abundance, broad distribution, and ability to exploit most types of freshwater habitats illustrate the
importance of aquatic insects. In this chapter, the adaptations that contribute to their success are described. Examples of how some
species have adapted their life cycle to restricted environments are used to provide a framework for describing ways that insects cope
with challenges of the aquatic habitat. Extensive table of oviposition habits, egg mass characteristics, and references to life history
descriptions are given for representative species in 10 insect orders.
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373. Wallace, J., Bruce; Eggert, S.L.; Meyer, Judy L.; Webster, J.R. 1999. Effects of resource limitation on a detrital-based
ecosystem. Ecological Monographs. 69(4): 409-442.
We examined the importance of terrestrial detrital inputs to secondary productivity of a headwater stream. Following a year of
pretreatment studies on two headwater streams, we excluded terrestrial litter inputs (= treatment) to one stream while using the other as a
reference. We excluded litter for 3 yr followed by 1 yr of small woody debris (≤ 10 cm diameter) removal and litter exclusion. Monthly
benthic samples were collected from dominant mixed substrate (cobble, pebble, and sand-silt) as well as from moss-covered bedrock
outcrop substrates. We used randomized intervention analysis (RIA) to test the null hypotheses that no change in abundance or biomass
of functional feeding groups or specific taxa occurred in the treatment stream relative to the reference stream. Benthic organic matter
was significantly lower in mixed substrate habitats of the treatment stream; however, small wood debris did not show a significant
reduction prior to manual removal during year 4. At the end of the treatment period, total benthic invertebrate abundance in mixed
substrates in the treatment stream was less than one-tenth of that in the reference stream, and biomass in the treatment stream was onesixth of that in the reference stream. Biomass and abundance of shredders, gatherers, total primary consumers, and predators displayed
significant treatment effects (P<0.012-0.00001, RIA) in the mixed substrate habitats during the 4-yr treatment. Only scraper and filterer
functional groups failed to show differences between streams during the 4-yr treatment. Twenty of the 30 taxa comprising >90% of total
secondary production displayed a significant decrease in abundance, biomass, or both, in the treatment stream relative to the reference
stream (P < 0.05, RIA). Total secondary production in mixed substrate habitats declined to 22% of pretreatment values by the fourth year
of treatment and is among the lowest reported for streams. Removal of small woody debris resulted in an additional 47-50% decreased in
abundance, biomass, and production of the benthic fauna compared to the third year of litter exclusion. In contrast, fauna of mosscovered bedrock substrates displayed no significant differences between streams in terms of any functional group, or in terms of
abundance and biomass of individual taxa. Furthermore, secondary production on bedrock outcrops remained similar between streams.
Results strongly suggest that food webs of bedrock habitats are not as closely linked to immediate allochthonous inputs from the
surrounding forest as those of mixed substrates, although they may be linked in the long term. Using a 9-yr record, we determined the
relationship between organic matter standing crop and invertebrate abundance biomass, and production in the treatment stream. There is
a strong relationship between leaf litter standing crops and secondary productivity in mixed substrate habitats. In contrast, bedrock
outcrop fauna showed a stronger relationship to fine benthic organic matter (FBOM) standing crop than to leaf litter. Despite a large
residual mass of organic matter in the treatment stream, as well as other ongoing sources of input (dissolved organic matter, soil organic
matter, and through fall), litter exclusion clearly shows strong bottom-up effects extending from primary consumers to predators.
Abundance, biomass, and production of predators in the treatment stream were also strongly related to that of their prey throughout all
pretreatment years. Our results, suggests that, owing to simple bioenergetics efficiencies, production of predators is constrained by
productivity of their prey. Although our results clearly show strong bottom-up effects, the importance of predators (top-down) cannot be
ignored, as available data suggest that predators consume most benthic invertebrate production. Our study underscores the importance of
terrestrial-aquatic linkages in maintaining productivity of headwater streams draining forested catchments.
374. Wallace, J. Bruce; Cuffney, T.F.; Eggert, S.L.; Whiles, M.R. 1997. Stream organic matter inputs, storage, and export for
satellite branch at Coweeta Hydrologic Laboratory, North Carolina, USA. In: Webster, J.R ; Meyer, J.L., eds. Stream organic matter
budgets. Journal of the North American Benthological Society. 16: 67-74.
This chapter is part of a multi-site analysis of organic matter dynamics in streams. This chapter describes data from Satellite Branch at
Coweeta Hydrologic Laboratory.
375. Wallace, J. Bruce; Grubaugh, Jack W. 1996. Transport and storage of FPOM. In: Hauer, F.R.; Lamberti, G.A., eds. Methods
in stream ecology. San Diego, CA: Academic Press, Inc: 191-215. Chapter 10.
This chapter describes methods for assessing fine particulate organic matter (FPOM) and fine benthic organic matter (FBOM) in
streams. Objectives are to: (1) introduce the reader to the importance and magnitude of FPOM transport in streams, (2) demonstrate
techniques for collecting and analyzing seston and FBOM, (3) demonstrate the importance of hydrologic events in seston transport
compared to base flow conditions. (4) compare the relative importance of erosional and depositional habitats in FBOM storage in
streams, and (5) illustrate direct consumption of suspended particles by filter-feeding larvae of black flies. Detailed plans are given for
sampling and analyses, including a list of supplies required.
376. Wallace, J. Bruce; Grubaugh, Jack W.; Whiles, Matt R. 1996. Influences of coarse woody debris on stream habitats and
invertebrate biodiversity. In: McMinn, James W.; Crossley, D.A., Jr., eds. Biodiversity and coarse woody debris in southern forests:
Proceedings of the workshop on coarse woody debris in southern forests: effects on biodiversity; 1993 October 18-20; Athens, GA. Gen.
Tech. Rep. SE-94. U.S. Department of Agriculture, Forest Service, Southern Research Station: 119-129.
Coarse woody debris (CWD) serves a number of important roles in stream ecosystems. For example, it retains organic and inorganic
matter, provides food for invertebrates, and serves as habitat for both invertebrates and fish. Stream invertebrates apparently further the
decomposition of CWD in freshwaters by scraping, gouging, and tunneling wood colonized by microbiota. Evidence is presented that the
distribution of CWD varies among streams in different Southeastern ecoregions. The impact of woody debris on the availability of food
resources, invertebrate colonization, taxonomic diversity, and community structure differs greatly between Appalachian and Coastal
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Plain streams. The primary reason for this is the availability of other sources of stable substrata in the latter. We compare and contrast
some of the effects of CWD on invertebrate communities among stream types of the Southeastern United States.
377. Wallace, J. Bruce; Grubaugh, Jack W.; Whiles, Matt R. 1996. Biotic indices and stream ecosystem processes: results from an
experimental study. Ecological Applications. 6(1): 140-151.
The North Carolina Biotic Index (NCBI) and the Ephemeroptera + Plecoptera + Trichoptera (EPT) index were used to track an
experimental manipulation of the invertebrate community and resultant alteration of several ecosystem-level processes in a headwater
stream at the Coweeta Hydrologic Laboratory. Indices were calculated from monthly or bimonthly benthic samples of moss-covered
rockface and mixed substrate habitats in two streams. One stream served as a reference stream over a 6-yr period, whereas the other
received seasonal treatments with an insecticide for 3 years. Throughout pretreatment, treatment, and recovery, both the NCBI and EPT
indices strongly tracked the disturbance regime of the treatment stream while indices for the reference stream varied little. Following
cessation of insecticide treatments, both indices reflected improved biotic conditions during first and second years of recovery.
Compared with fauna of mixed substrates, rockface fauna had better NCBI values during pretreatment, and exhibited a greater increase
in tolerant taxa during treatment than mixed substrates, emphasizing the importance of including rockface communities in monitoring
programs. Changes in both the EPT and NCBI indices closely corresponded to changes in ecosystem-level processes observed over
pretreatment, treatment, and recovery periods. Processes include: leaf litter processing rates, organic matter storage, fine particulate
organic matter generation and export, and secondary production. The EPT index was by far the easiest to use from both the standpoint of
time required for sample processing and ease of application. Our data strongly support using EPT and NCBI indices in southern
Appalachian headwater streams as indicators of both degradation and recovery of stream ecosystem processes.
378. Wallace, J. Bruce; Webster, Jackson R. 1996. The role of macroinvertebrates in stream ecosystem function. Annual Review of
Entomology. 41: 115-139.
This review focuses on some of the roles of macroinvertebrate functional groups, i.e. grazers, shredders, gatherers, filterers, and
predators, in stream-ecosystem processes. Many stream-dwelling insects exploit the physical characteristics of streams to obtain their
foods. As consumers at intermediate trophic levels, macroinvertebrates are influenced by both bottom-up and top-down forces in streams
and serve as the conduits by which these effects are propagated. Macroinvertebrates can have an important influence on nutrient cycles,
primary productivity, decomposition, and translocation of materials. Interactions among macroinvertebrates and their food resources
vary among functional groups. Macroinvertebrates constitute an important source of food for numerous fish, and unless outside energy
subsidies are greater than in-stream food resources for fish, effective fisheries management must account for fish-invertebrate linkages
and macroinvertebrate linkages with resources and habitats. Macroinvertebrates also serve as valuable indicators of stream degradation.
The many roles performed by stream-dwelling macroinvertebrates underscore the importance of their conservation.
379. Wallace, J. Bruce, Webster, Jackson R.; Eggert, Sue L.; Meyer, Judy L.; Siler, Edward R. 2001. Large woody debris in a
headwater stream: Long-term legacies of forest disturbance. International Review of Hydrobiology. 86(4-5): 501-513.
We excluded litter (leaves and wood) inputs to an Appalachian headwater stream for 5 years. Leaves disappeared from the streambed
very rapidly (<1 year) following litter exclusion, however, a large residual mass of woody debris remained. After excluding inputs of
leaf litter and wood to the stream for 3 years we removed all small wood (<10 cm diameter) from the stream. There was close agreement
(within 10%) between estimates of mass of small woody debris made using line intersect methods and that made by direct removal. Two
years later, we removed all large woody debris (LWD = > 10 cm diameter) from the wetted perimeter of the stream. Five annual
estimates of LWD mass made with line intersect methods exceeded those of complete removal by a factor of about 2x, although total
wood removed was within the 95% confidence interval of that estimated by the line intersect method. Species of wood removed from the
stream displayed weak similarity (percent similarity = 45 to 49%) with recent (1993 and 1972) measures of basal area of tree species in
the surrounding forest, but stronger similarity (65%) with tree species measured in 1934. About 37% of the LWD removed consisted of
American chestnut, Castanea dentate, (~24%) and black locust, Robinia pseudoacacia, (~14%), which currently represent < 1.5 % of the
basal area of the surrounding forest. LWD in the stream reflects large inputs of chestnut following the chestnut blight in the 1930’s and
inputs of early successional species such as black locust following extensive timber harvesting in the early 1920s. These earlier
disturbances to the forest were important sources of LWD that remain in the stream today. Thus, the structure and function of present
day streams are influenced by forest disturbances that occurred over six decades ago.
380. Wallace, J. Bruce; Webster, Jackson R.; Meyer, Judith L. 1995. Influence of log additions on physical and biotic
characteristics of a mountain stream. Canadian Journal of Fisheries and Aquatic Sciences. 52: 2120-2137.
Three pairs of cobble riffle study sites were established in a second-order stream in North Carolina and logs added to the downstream
riffle at each site. At log addition transects, stream depth increased, current velocity decreased, cobble substratum was covered by sand
and less dramatic effects on uptake lengths of ammonium, nitrate, and phosphate, but they had immediate and significant impacts on
invertebrate community structure: abundances and biomass of scrapers and filterers decreased; collectors and predators increased;
overall shredder biomass did not change, but biomass of trichopteran and dipteran shredders increased, while that of most plecopteran
shredders decreased; and plecopteran predators also decreased despite greater abundances of potential prey. These observations suggest
that physiological and morphobehavioral constraints preclude many animals from tracking resources among patches when patches
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display very different abiotic conditions. Secondary production of scrapers and filterers decreased, whereas that of collectors and
predators increased. The shifts in functional group abundances, biomass, and production between reference and debris-dam transects,
which differed considerable from those previously reported for low-gradient, sandy-bottom streams, accentuate the importance of
localized abiotic factors in structuring invertebrate communities within patches.
381. Wallace, J. Bruce; Whiles, Matt R.; Eggert, Sue; Cuffney, T.F.; Lugthart, G.J.; Chung, K. 1995. Long-term dynamics of
coarse particulate organic matter in three Appalachian mountain streams. Journal of the North American Benthological Society. 14(2):
217-232.
Export of coarse particulate organic matter (CPOM) from three headwater streams at Coweeta was studied continuously for up to 9.5
years. Annual CPOM export among years varied by factors of 9.2 to > 16 X, much greater than the 3.5 to 5.0 X variation in annual
stream discharge. Annual export was more a factor of storm frequency and magnitude. Over 63 to > 77% of all CPOM export occurred
during the largest 20 storms. Export during individual sampling intervals was strongly related to maximum discharge. Leaf export was
greatest during the autumn and lowest during the spring and summer months. Export of woody debris was more seasonally variable than
that of leaves. Although allochthonous CPOM is the greatest source of organic matter inputs, CPOM represented only 1.8-3.8% of total
organic matter export, indicating high retention in these small, high-gradient streams. Retentiveness was illustrated by movement of
marked artificial "leaves" and "sticks", which displayed maximum downstream movement of ~42 m/yr for "leaves" and 10 m/yr for
"sticks". For three years, one stream received seasonal treatments of an insecticide that drastically reduced invertebrate populations.
Large increases in leaf litter standing crop were observed compared with untreated streams. However, CPOM export did not increase
significantly whereas a massive reduction in FPOM export was found.
382. Wallace, J. Bruce; Whiles, M.R.; Webster, J.R.; Cuffney, T.F.; Lugthart, G.J.; Chung, K. 1993. Dynamics of inorganic
particles in headwater streams: linkages with invertebrates. Journal of the North American Benthological Society. 12(2): 112-125.
Export of particulate inorganic matter (PIM) from three headwater streams was studied from 1985 to 1991 at Coweeta Hydrologic
Laboratory. The study encompassed years of extreme high and low precipitation. During three years of the study, one stream received
seasonal treatments of an insecticide. This treatment greatly reduced abundance biomass and secondary production of most invertebrate
taxa. During treatment, concentration of PIM decreased significantly from pretreatment levels. Invertebrate manipulation apparently
reduced PIM export by at least two mechanisms. First, the rate of particle generation by feeding activities was reduced. Second, reduced
rates of leaf litter processing resulted in increased storage of leaf litter and enhanced retention of particles. These comparisons exceed
those made previously for the impact of invertebrate manipulation on FPOM export and provide another example of the link between
animal communities and ecosystem processes.
383. Waterman, Jayson R.; Gillespie, Andrew R.; Vose, James M.; Swank, Wayne T. 1995. The influence of mountain laurel on
regeneration in pitch pine canopy gaps of the Coweeta Basin, North Carolina, U.S.A. Canadian Journal of Forest Research. 25: 17561762.
Because of its dense nature, mountain laurel (Kalmia latifolia L.) understories may be retarding the regeneration of xeric pitch pine
(Pinus rigida Mill.) sites in the southern Appalachians and thereby influencing successional dynamics. This study examined the impact
of the laurel understory on hardwood successional ecology in living pitch pine stands and pine gaps at their upper and lower elevational
distribution. The laurel understory was physically removed from half the plots; the remaining plots served as a control. The plots were
inventoried and all seedlings were tagged and measured to determine importance values, recruitment, survivorship, and biomass for 2
years following treatment. The results indicate that the presence or absence of the laurel understory does not affect initial seedling
recruitment, and survivorship, or their relative competitiveness. However, mountain laurel does suppress growth of smaller seedlings.
Given the higher importance value, recruitment, and survivorship of red maple (Acer rubrum L.), the regeneration layer in these pitch
pine sites is currently dominated by red maple, with scarlet oak (Quercus coccinea Muenchh.) and other xeric-site hardwoods as
associates. With the adaptive ability of red maple to take advantage of openings, red maple will continue to dominate and ultimately
regenerate these communities with other hardwoods as minor associates.
384. Watwood, Mary E.; Sommer, A. Stefan; Fitzgerald, John W. 1994. Biological sulfur retention in surface soils as a predictor
of ecosystem sensitivity to acidic precipitation. Soil Science (Trends in Agriliculture Science). 1: 103-111.
Three processes affecting sulfate retention were measured for A horizon soils from eleven US forest sites. These were physico-chemical
sulfate absorption of 35S-sulfate, biological incorporation of added 35S-sulfate into organic matter, and subsequent mobilization
(depolymerization followed by mineralization) of biologically formed 35S-organic sulfur. The last two values were used to calculate the
net biological sulfate retention for each soil. Values for the ecosystem wide leaching loss of the cationic plant nutrients Ca2+, Mg2+, and
K+, based on precipitation inputs and streamflow losses for each site, were used as indicators of ecosystem sensitivity to sulfates derived
from acidic precipitation. Although many of the A horizon soils exhibited substantial amounts of physico-chemical sulfate adsorption,
this process was not correlated with ecosystem wide cation leaching loss. Mobilization of organic sulfur was positively correlated to
ecosystem wide cation loss. Both gross biological incorporation and net biological sulfur retention showed strong negative correlation
with ecosystem wide cation loss. Thus, soils with high capacity for biological sulfate retention experience less ecosystem wide cation
leaching loss and should be less sensitive to acidic deposition related sulfate inputs.
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385. Wear, David N.; Bolstad, Paul. 1998. Land-use changes in southern Appalachian landscapes: spatial analysis and forecast
evaluation. Ecosystems. 1: 575-594.
Understanding human disturbance regimes is crucial for developing effective conservation and ecosystem management plans and for
targeting ecological research to areas that define scarce ecosystem services. We evaluate and develop a forecasting model for land-use
change in the Southern Appalachians. We extend previous efforts by (a) addressing the spatial diffusion of human populations,
approximated by building density, (b) examining a long time period (40 years, which is epochal in economic terms), and (c) explicitly
testing the forecasting power of the models. The resulting model, defined by linking a negative binomial regression model of building
density with a logit model of land cover, was fit using spatially referenced data from four study sites in the Southern Appalachians. All
fitted equations were significant, and coefficient estimates indicated that topographic features as well as location significantly shape
population diffusion and land use across these landscapes. This is especially evident in the study sites that have experienced development
pressure over the last 40 years. Model estimates also indicate significant spatial autocorrelation in land-use observations. Forecast
performance of the models was evaluated by using a separate validation data set for each study area. Depending on the land-use
classification scheme, the models correctly predicted between 68% and 89% of observed land uses. Tests based on information theory
reject the hypothesis that the models have no explanatory power, and measures of entropy and information gain indicate that the
estimated models explain between 47% and 66% of uncertainty regarding land-use classification. Overall, these results indicate that
modeling land-cover change alone may not be useful over the long run, because changing land cover reflects the outcomes of more than
one human process. Here, additional information was gained by addressing the spatial spread of human populations. Furthermore,
coarse-scale measures of the human drivers of landscape change appear to be poor predictors of changes realized at finer scales.
Simulations demonstrate how this type of approach might be used to target scarce resources for conservation and research efforts into
ecosystem effects.
386. Wear, David N.; Turner, Monica G.; Flamm, Richard O. 1996. Ecosystem management with multiple owners: Landscape
dynamics in a southern Appalachian watershed. Ecological Applications. 6(4): 1173-1188.
Ecosystem management is emerging as an organizing theme for land use and resource management in the United States. However, while
this subject is dominating professional and policy discourse, little research has examined how such system-level goals might be
formulated and implemented. Effective ecosystem management will require insights into the functioning of ecosystems at appropriate
scales and their responses to human interventions, as well as factors such as resource markets and social preferences that hold important
influence over land and resource use. In effect, such management requires an understanding of ecosystem processes that include human
actors and social choices. We examine ecosystem management issues using spatial models that simulate landscape change for a study
site in the southern Appalachian highlands of the United States. We attempt to frame a set of ecosystem management issues by
examining how this landscape could develop under a number of different scenarios designed to reflect historical land-cover dynamics as
well as hypothetical regulatory approaches to ecosystem management. Scenarios based on historical change show that recent shifts in
social forces that drive land cover change on both public and private lands imply a more stable and a more forested landscape. Scenarios
based on two hypothetical regulatory instruments indicate that public land management may have only limited influence on overall
landscape pattern and that spatially targeted approaches on public and private lands may be more efficient than blanket regulation for
achieving landscape-level goals.
387. Wear, David N.; Turner, Monica G.; Naiman, Robert J. 1998. Land cover along an urban-rural gradient: Implications for
water quality. Ecological Applications. 8(3): 619-630.
Development pressures in rural mountainous areas of the United States hold crucial implications for water quality. Especially important
are changes in the extent and pattern of various land uses. We examine how position along an urban-rural gradient affects landscape
patterns in a southern Appalachian watershed, first by testing for the effect of distance from an urban center on land-cover change
probabilities and then simulating the implied development of a landscape at regular distance intervals. By simulating a common
hypothetical landscape we control for variable landscape conditions and define how land development might proceed in the future.
Results indicate that position along the urban-rural gradient has a significant effect on land-cover changes on private lands but not on
public lands, Furthermore, position along the gradient has a compounding effect on land-cover changes through interactions with other
variables such as slope. Simulation results indicate that these differences in land-cover changes would give rise to unique "landscape
signatures" along the urban-rural gradient. By examining a development sequence, we identify patterns of change that may be most
significant for water quality. Two locations along the urban-rural gradient may hold disproportionate influence over water quality in the
future: (1) at the most remote portion of the landscape and (2) at the outer envelope of urban expansion. These findings demonstrate how
landscape simulation approaches can be used to identify where and how land use decisions may have critical influence over
environmental quality, thereby focusing both future research and monitoring efforts and watershed protection measures.
388. Webster, J.R.; Benfield, E.F.; Ehrman, T.P.; Schaeffer, M.A.; Tank, J.L.; Hutchens, J.J.; D’angelo, D.J. 1999. What
happens to allochthonous material that falls into streams? A synthesis of new and published information from Coweeta. Freshwater
Biology. 41: 687-705.
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1. One of two things can happen to allochthonous material once it enters a stream: it can be broken down or it can be transported
downstream. The efficiency with which allochthonous material is used is the result of these two opposing factors: breakdown and
transport.
2. The present synthesis of new and published studies at Coweeta Hydrologic Laboratory compares biological use versus transport for
four categories of particulate organic material: (1) large wood (logs); (2) small wood (sticks); (3) leaves; and (4) fine particulate organic
matter (FPOM).
3. Over 8 years, logs showed no breakdown or movement.
4. The breakdown rate of sticks (≤3 cm diameter) ranged from 0.00017 to 0.00103 day-1, while their rate of transport, although varying
considerably with discharge, ranged from 0 to 0.1 m day-1.
5. Based on 40 published measurements, the average rate of leaf breakdown was 0.0098 day-1. The leaf transport rate depended on
stream size and discharge.
6. The average respiration rate of FPOM was 1.4 mg O2 g AFDM-1 day-1 over a temperature range of 6-22 °C, which implies a
decomposition rate of 0.00104 day-1 Transport distances of both corn pollen and glass beads, surrogates of natural FPOM, were short (<
10 m) except during high discharge.
7. Estimates of transport rate were substantially larger than the breakdown rates for sticks, leaves and FPOM. Thus, an organic particle
on the stream bottom is more likely to be transported than broken down by biological processes, although estimates of turnover length
suggest that sticks and leaves do not travel far. However, once these larger particles are converted to refractory FPOM, either by physical
or biological processes, they may be transported long distances before being metabolized.
389. Webster, J.R.; Benfield, E.F.; Hutchens, J.J.; Tank, J.L.; Golladay, S.W.; Adams, J.C. 2001. Do leaf breakdown rates
actually measure leaf disappearance from streams? International Review of Hydrobiology. 86(4-5): 417-427.
We measured leaf input, leaf breakdown, and benthic leaf standing stock in Hugh White Creek, a second-order, Appalachian Mountain
stream in North Carolina. U.S.A. Leaf input and leaf breakdown data were used in a computer model to predict standing stocks.
Predicted standing stocks were then compared with measured values. Once the model was modified to include leaves in four breakdown
rate categories, leaf blow-in, and temperature effects on leaf breakdown, agreement between model prediction and measurement was
quite good.
390. Webster, J.R.; Covich, A.P.; Tank, J.L.; Crockett, T.V. 1994. Retention of coarse organic particles in streams in the southern
Appalachian mountains. Journal of the North American Benthological Society. 13(2): 140-150.
Retention of coarse particulate organic matter (CPOM) is essential to the efficient use of organic matter in streams supported by
allochthonous inputs. Both long-term and short-term experiments to measure retention were conducted at Coweeta using small dowels as
indices of stick retention and pieces of paper as indices of leaf retention. In general, both types of CPOM were efficiently retained in all
streams. Factors that affected CPOM transport and retention were storms, stream size, stream depth, and the abundance of retention
structures in the streams. After initial transport, woody CPOM was transported only during storms. Retention was greater in smaller
streams and in shallower stream sites. Rocks, boulders, and woody debris were the most important retention structures. In the stream
draining a logged catchment, lower CPOM retention was associated with lower abundance of woody debris dams.
391. Webster, J.R.; D'Angelo, D.J. 1997. A regional analysis of the physical characteristics of streams. In: Webster, J.R.; Meyer,
J.L., eds. Stream organic matter budgets. Journal of the North American Benthological Society. 16: 87-95.
This chapter is part of a multi-site analysis of organic matter dynamics in streams. This chapter compares the physical characteristics of
the 36 streams. Stream size, water temperature, and precipitation were the most important variables setting the physical template for
organic matter processes occurring in the streams.
392. Webster, J.R.; Meyer, J.L. (eds). 1997. Stream organic matter budgets. Journal of the North American Benthological Society.
16: 3-161.
This analysis of organic matter dynamics in streams has 3 objectives: 1) to explore the relationships between physical characteristics of
streams and their watersheds (climate, geomorphology) and stream organic matter dynamics using data from a broad geographic area; 2)
to compare stream organic matter dynamics in a diverse array of streams in order to suggest determinants of observed patterns; and 3) to
reveal deficiencies in currently available data on organic matter dynamics in streams. The introductory chapter describes the kinds of
data included for each stream and provides brief descriptions of previously published organic matter data for streams included in the
comparative analysis but not described in individual chapters. The next 16 chapters present organic matter data for streams from North
America, Europe, Australia, and Antarctica. Most of the streams represented are in the temperate zone of North America. Data presented
include climate and geomorphic variables and organic matter inputs, exports, and standing crops. The chapters on individual streams are
followed by 7 chapters analyzing physical features of these streams and specific components of the organic matter budgets.
393. Webster, J.R.; Meyer, J.L. 1997. Organic matter budgets for streams: a synthesis. In: Webster, J.R.; Meyer, J.L., eds. Stream
organic matter budgets. Journal of the North American Benthological Society. 16: 141-161.
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This chapter is part of a multi-site analysis of organic matter in dynamics in streams. This final chapter is a synthesis of the organic
matter dynamics in streams. This final chapter is a synthesis of the organic matter budgets. The factors analyzed were P/R ratio,
allochthonous versus autochthonous inputs, stream ecosystem efficiency, turnover length, stream metabolism index, and turnover time.
We reached two conclusions: 1) At a global level, stream organic matter dynamics are driven primarily by climate through its effect on
terrestrial vegetation. 2) Despite significant progress in understanding organic matter processes in streams, many of the differences we
found among steams reflect omissions of important components of the budget, especially accurate measures of streambed area,
heterotrophic respiration, FBOM standing stock, and groundwater inputs of DOM.
394. Webster, J.R.; Meyer, J.L. 1997. Stream organic matter budgets-introduction. In: Webster, J.R.; Meyer, J.L., eds. Stream
organic matter budgets. Journal of the North American Benthological Society. 16: 5-13.
This chapter is part of a multi-site analysis of organic matter dynamics in streams. In this introductory chapter, we describe the kinds of
data included for each stream and provide brief descriptions of previously published organic matter data for streams included in the
comparative analysis but not described in individual chapters.
395. Webster, J.R.; Meyer, J.L.; Wallace, J.B.; Benfield, E.F. 1997. Organic matter dynamics in Hugh White Creek, Coweeta
Hydrologic Laboratory, North Carolina, USA. In: Webster; J.R.; Meyer, J.L., eds. Stream organic matter budgets. Journal of the North
American Benthological Society. 16: 74-78.
This chapter is part of a multisite analysis of organic matter dynamics in streams. This chapter describes data from Hugh White Creek at
Coweeta Hydrologic Laboratory.
396. Webster, J.R.; Tank, J.L.; Wallace, J.B.; Meyer, J.L.; Eggert, S.L.; Ehrman, T.P.; Ward, B.R.; Bennett, B.L.; Wagner,
P.F.; McTammany, M.E. 2000. Effects of litter exclusion and wood removal on phosphorus and nitrogen retention in a forest stream.
Verhandlungen International Verinigung Limologie. 27: 1337-1340.
Many studies in the past have shown indirect evidence of the importance of terrestrial detritus in woodland streams, but recently Wallace
et al. (1997b) eliminated leaf and wood inputs to a small stream and directly demonstrated the importance of this material to stream food
webs. Additionally this whole-stream experiment has shown that terrestrial detritus is more than just food for invertebrates. Tank &
Webster (1998) found accelerated wood biofilm development and wood decomposition in the litter exclusion stream, and Meyer et al.
(1998) used the litter exclusion experiment to estimate that leaves contribute approximately 30% of dissolved organic carbon exports.
Previous studies have also suggested that leaf litter in streams is important to nutrient retention (Mulholland et al. 1985, Elwood et. Al
1988.) The purpose of the current study was to examine the effects of liter exclusion and wood removal on retention of dissolved
nutrients.
397. Webster, J.R.; Wallace, J.B.; Benfield, E.F. 1995. Organic processes in streams of the eastern United States. In: Cushing, C.E.;
Cummins, K.W.; Minshall, G.W., eds. Ecosystems of the World 22: River and stream ecosystems. New York, NY: Elsevier: 117-187.
Chapter 6.
This paper presents data on natural factors that affect streams in the eastern United States with an emphasis on climate, physiography,
vegetation, geochemistry, and hydrology. These factors provide a template upon which the organic processes of streams operate. Organic
processes in streams are further affected by anthropogenic disturbances, which are discussed within the context of specific organic
processes.
398. Webster, Jackson R.; Ehrman, Terrance P. 1996. Solute dynamics. In: Hauer, F.R.; Lamberti, G.A., eds. Methods in stream
Ecology. San Diego, CA: Academic Press, Inc: 145-160. Chapter 8.
In this chapter, stream solute dynamics is investigated from the perspectives of: 1) providing information on rates of transport,
transformation, and availability of solutes and 2) quantifying various hydrologic properties of a steam. Experimental designs are
described which examine the dynamics of both conservative and nonconservative solutes in a variety of streams.
399. Webster, Jackson R.; Mulholland, Patrick J.; Tank, Jennifer L.; Valett, H. Maurice; Dodds, Walter K.; Peterson, Bruce
J.; Bowden, William B.; Dahm, Clifford N.; Findlay, Stuart; Gregory, Stanley V.; Grimm, Nancy B.; Hamilton, Stephen K.;
Johnson, Sherri L.; Marti, Egenia; McDowell, William H.; Meyer, Judy L.; Morrall, Donna D.; Thomas, Steven A.; Wollheim,
Wilfred M. 2003. Factors affecting ammonium uptake in streams – an inter-biome perspective. Freshwater Biology. 48: 1329-1352.
1. The Lotic Intersite Nitrogen eXperiment (LINX) was a coordinated study of the relationships between North American biomes and
factors governing ammonium uptake in streams. Our objective was to relate inter-biome variability of ammonium uptake to physical,
chemical and biological processes.
2. Data were collected from 11 streams ranging from arctic to tropical and from desert to rainforest. Measurements at each site included
physical, hydraulic and chemical characteristics, biological parameters, whole-stream metabolism and ammonium uptake. Ammonium
uptake was measured by injection of 15N-ammonium and downstream measurements of 15N-ammonium concentration.
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3. We found no general, statistically significant relationships that explained the variability in ammonium uptake among sites. However,
this approach does not account for the multiple mechanisms of ammonium uptake in streams. When we estimated biological demand for
inorganic nitrogen based on our measurements of in-stream metabolism, we found good correspondence between calculated nitrogen
demand and measured assimilative nitrogen uptake.
4. Nitrogen uptake varied little among sites, reflecting metabolic compensation in streams in a variety of distinctly different biomes
(autotrophic production is high where allochthonous inputs are relatively low and vice versa).
5. Both autotrophic and heterotrophic metabolism require nitrogen and these biotic processes dominate inorganic nitrogen retention in
streams. Factors that affect the relative balance of autotrophic and heterotrophic metabolism indirectly control inorganic nitrogen uptake.
400. Weinstein, David A.; Cropper, Wendell P., Jr.; McNulty, Steven G. 1998. Summary of simulated forest responses to climate
change in the Southeastern US. In: Mickler, Robert A.; Fox, Susan, eds. The productivity and sustainability of southern forest
ecosystems in a changing environment. Ecological Studies, vol. 128. New York, NY: Springer-Verlag: 479-500.
Climate change impact models can range from being completely empirical to completely physiological. Empirical models are based on
historic observations of forest ecosystem response to climate variability, while physiological models are based on process level
interactions between vegetation and the environment. Each type of model has certain advantages and disadvantages. This paper
examines nine forest process models that examined the impacts of climate change on productivity across the southern US. Additionally,
some models also incorporated the impacts of nitrogen deposition and ozone on forest function. Despite the wide range in model
structure, there was general agreement between the models that the more moderate climate change scenarios (i.e., OSU, GISS, GFDL)
with an average annual air temperature increase up to 3.5°C would have little impact on forest productivity while a severe climate
change scenario (i.e., UKMO) with an average annual air temperature increase of 7.5°C could potentially severely reduce productivity in
the region.
401. Whiles, M.R.; Wallace, J. Bruce. 1992. First-year benthic recovery of a headwater stream following a 3-year insecticideinduced disturbance. Freshwater Biology. 28: 81-91.
A headwater stream was treated seasonally with the insecticide methoxychlor for 3 years, resulting in reductions of insect abundances
and biomass. Following treatment, monthly benthic abundances and biomass were measured in the treated stream and a nearby reference
stream to assess recovery. Non-insect abundances and biomass were higher in the recovering stream during the winter + spring and
summer periods, but were similar to the reference stream by autumn. Abundances and biomass of collector-filterers, scrapers, and
shredders were all lower in the recovering stream during winter + spring; however, filterers and scrapers were similar to reference stream
values by the end of the recovery year. No distinct differences were seen between collector-gatherers and predators throughout the year.
Univoltine and multivoltine taxa, along with treatment-resistant taxa, were the most important contributors to recovery.
402. Whiles, Matt R.; Wallace, J. Bruce. 1995. Macroinvertebrate production in a headwater stream during recovery from
anthropogenic disturbance and hydrologic extremes. Canadian Journal of Fisheries and Aquatic Sciences. 52: 2402-2422.
Recovery of the macroinvertebrate community inhabiting a headwater stream that received 3 years of seasonal insecticide treatment was
investigated. Estimates of abundance, biomass, and production in C54 during 1989 and 1990 were compared with those of a nearby
undisturbed reference stream, and those of C54 during a pretreatment year. Total macroinvertebrate abundance was similar throughout
pretreatment, treatment, and recovery periods of C54. In contrast, biomass and production, which decreased during treatment, increased
to levels similar to those of C54 in the pretreatment year and those of the reference stream during recovery. By 1990, the functional
structure of C54 was similar to that of C55 and that of C54 before the treatment. However, taxonomic and developmental stage
differences within some functional groups, particularly shredders, persisted. Despite poor recovery of some larger shredder taxa, rapid
recovery of a relatively small trichopteran shredder, Lepidostoma spp., contributed significantly to recovery of ecosystem processes
associated with shredders. Relationships between shredder biomass and coarse particulate organic matter differed during treatment and
recovery periods. Invertebrate taxa with shorter life cycles recolonized rapidly, while those with life cycles > 1 year generally displayed
limited recovery. Hydrologic extremes during treatment (drought) and recovery (wet) periods affected organic matter and
macroinvertebrate community dynamics in both streams, and may have influenced observed recovery patterns.
403. Whiles, Matt R.; Wallace, J. Bruce; Chung, Keun. 1993. The influence of Lepidostoma (Trichoptera: Lepidostomatidae) on
recovery of leaf-litter processing in disturbed headwater streams. American Midland Naturalist. 130: 356-363.
Two headwater streams draining catchments at Coweeta Hydrologic Laboratory were treated with insecticide. During recovery periods
in both streams, Lepidoptera spp. were abundant, early colonizers. During treatment years, leaf-litter processing rates were severely
reduced relative to pretreatment and reference streams. In contrast, letter-processing rates during recovery were faster than those in
untreated streams. Rhododendron is one of the most refractory leaves commonly found in Coweeta streams; however, percent increase of
rhododendron processing rates from treatment periods to recovery was greater than that of more labile red maple. Results suggest that
changes in the taxonomic composition of stream macroinvertebrate communities due to disturbance may have significant effects on
ecosystem processes for at least 2 years after termination of disturbance.
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404. Whitman, William B.; Coleman, David C.; Wiebe, William J. 1998. Prokaryotes: the unseen majority. In: Proceedings of the
national academy of sciences USA. 95(12): 6578-6583.
The number of prokaryotes and the total amount of their cellular carbon on earth are estimated to be 4-6 X 1030 cells and 350-550 Pg of
C (1 Pg = 1015 g), respectively. Thus, the total amount of prokaryotic carbon is 60-100% of the estimated total carbon in plants, and
inclusion of prokaryotic carbon in global models will almost double estimates of the amount of carbon stored in living organisms. In
addition, the earth's prokaryotes contain 85-130 Pg of N and 9-14 Pg of P, or about 10-fold more of these nutrients than do plants, and
represent the largest pool of these nutrients in living organisms. Most of the earth's prokaryotes occur in the open ocean, in soil, and in
oceanic and terrestrial subsurfaces, where the numbers of cells are 1.2 X 1029, 2.6 X 1029, 3.5 X 1030, and 0.25-2.5 X 1030, respectively.
The numbers of heterotrophic prokaryotes in the upper 200 m of the open ocean, the ocean below 200 m, and soil are consistent with
average turnover times of 6-25 days, 0.8 yr, and 2.5 yr, respectively. Although subject to a great deal of uncertainty, the estimate for the
average turnover time of prokaryotes in the subsurface is on the order of 1-2 X 103 yr. The cellular production rate for all prokaryotes on
earth is estimated at 1.7 x 1030 cells/yr and is highest in the open ocean. The large population size and rapid growth of prokaryotes
provides an enormous capacity for genetic diversity.
405. Wohl, Debra L.; Wallace, J. Bruce; Meyer, Judith L. 1995. Benthic macroinvertebrate community structure, function, and
production with respect to habitat type, reach, and drainage basin in the southern Appalachians (U.S.A.). Freshwater Biology. 34: 447464.
Benthic macroinvertebrates were sampled for 1 year to assess functional and taxonomic differences in invertebrate biomass and
production with respect to habitat types, reaches and catchments in Wine Spring Basin, western North Carolina. Quantitative samples
were collected from depositional, cobble-riffle and bedrock outcrop habitats at four stream reaches (two headwater sites, one-second
order, and one-third order). Other measures included physical parameters, periphyton and organic matter standing crops. Invertebrate
data from the Wine Spring catchment were also compared with data from another catchment (Ball Creek) within the same region. Sites
in both the Wine Spring and Ball Creek catchments exhibited similar functional group distributions per habitat type.
406. Worrall, F.; Swank, W.T.; Burt, T.P. 2003. Changes in stream nitrate concentrations due to land management practices,
ecological succession, and climate: Developing a systems approach to integratd catchment response. Water Resources Research: 39(7):
1177, doi: 10.1029/200WR000130.
[1] This study uses time series analysis to examine long-term stream water nitrate concentration records from a pair of forested
catchments at the Coweeta Hydrologic Laboratory, North Carolina, USA. Monthly average concentrations were available from 1970
through 1997 for two forested catchments, one of which was clear-felled in 1977 and the other maintained as a control. The time series
were decomposed into their trend and annual cycle before modeling as an autoregressive (AR) process. AR models were calculated for
both an expanding and a shifting window so that prefelling could be directly compared with the effects of tree clearance. In comparison
with flow records for both of the catchments, transfer function-noise models were calculated on a moving window basis, and the impulse
functions were derived. Analysis shows that both catchments show an annual memory effect but that the clear-felled catchment shows, in
addition, a 6-month memory effect. The annual effect in the control catchment responds to drought conditions while in the felled
catchment, it reflects the change in vegetation. The 6-month effect in the felled catchment responds to drought conditions independent of
both the annual effect and of logging operations. The control catchment shows no significant impulse function with respect to flow,
while for the felled catchment a distinct impulsivity develops over time subsequent to logging and coincident with the onset of nitrogen
saturation. By examining the nature of the nitrate export, rather than solely the levels of export, a systems approach can be taken to
understanding catchment behavior. Such an approach shows that the catchment is in metastable equilibrium with respect to its
hydrological pathways and nitrogen reserves but in dynamic equilibrium with respect to long-term temperature change. The onset of
nitrogen saturation may represent irreversible changes in the catchment behavior, and impulsivity, with respect to streamflow, represents
a new indicator of N-saturated conditions.
407. Wright, C.J.; Coleman, D.C. 2000. Cross-site comparison of soil microbial biomass, soil nutrient status, and nematode trophic
groups. Pedobiologia. 44: 2-23.
Soil microbial biomass, soil nutrient status, and nematode trophic groups were examined at the Coweeta. Harvard Forest and Hubbard
Brook Long Term Ecological Research (LTER) sites. Soils were divided into standardized depths (0-5 cm and 5-10 cm) for all analyses.
Microbial biomass, nematode abundance, and labile soil phosphorus levels were significantly higher in the 0-5 cm soil than in the 5-10
cm soil. Overall, both Harvard Forest and Hubbard Brook had greater nematode abundance and oil phosphorus than Coweeta, while
Harvard Forest had the highest levels of microbial biomass. Bacterial feeders, followed by fungal feeders and Tylenchidae were the
dominant nematode trophic group’s at all three sites. Soil factors such as organic matter, root biomass, and total soil C and N contributed
to increased levels of microbial biomass, nematode abundance and soil phosphorus levels. In contrast, litter quality and climatic factors
such as temperature and moisture apparently had little effect upon the parameters measured. This study illustrates the complex
interrelationships between decomposer communities, climate, litter quantity, litter quality, soil nutrients, and site-specific ecosystem
processes. Continued long-term, cross-site ecosystem studies remain necessary to better understand the complex and dynamic processes
causing variability both within and between ecosystems.
98
408. Wright, C.J.; Coleman, D.C. 2002. Responses of soil microbial biomass, nematode trophic groups, N-mineralization, and litter
decomposition to disturbance events in the southern Appalachians. Soil Biology & Biochemistry. 24: 13-25.
Seasonal measurements of soil microbial biomass, nematode trophic groups, net N-mineralization, net nitrification, net ammonification,
litter decomposition, and soil respiration rates were examined to assess the effects of rhododendron (Rhododendron maximum L.)
removal and hurricane windthrow upon these factors. Comparisons of pre- and post-disturbance quantities of soil microbial biomass
carbon ranged from 503 to 1080 µg C g soil ˉ1 and microbial biomass nitrogen ranged from 67 to 169 µg total persulfate nitrogen g soil
ˉ1, showing no significant differences or trends in response to these disturbance events. Total nematode abundance ranged from 13.05 to
54.31 nematodes g soil ˉ1 and showed no significant differences in response to these disturbance events, although overall nematode
abundance was declining in the disturbed plots at the end of the study. Nematode trophic structure was fairly consistent across both sites
and all sampling dates and exhibited no discernible trends in response to these disturbance events. Rates of net N-mineralization,
nitrification, and ammonification exhibited greater variability, post-disturbance. Litter decomposition rates and soil respiration rates
decreased following the disturbance events, with respiration rates in the Cut plot being significantly higher across years. Overall, the
effects of these disturbance events upon soil properties were highly variable and were unrelated to the major increases in N loss that were
detected from deeper soil horizons following the hurricane windthrow event.
409. Wright, Christina J.; Coleman, David C. 1999. The effects of disturbance events on labile phosphorus fractions and total
organic phosphorus in the southern Appalachians. Soil Science. 164(6): 391-402.
Changes in labile soil phosphorus pools, together with changes in organic matter and total organic soil phosphorus levels, were measured
following rhododendron harvest and hurricane windthrow events at the Coweeta Long Term Ecological Research (LTER) site. Seasonal
soil samples were taken every 3 months from June 1996 to September 1997. Soil Cores were taken along four transects with each study
area at distances approximately 1, 5, and 15 m upslope from the stream channel. Levels of resin P were low for all sites and sampling
dates (<5μg P04-P g soil-1). Levels of bicarbonate inorganic P were<8 μg P04-P g soil-1 for all sites and sampling dates, whereas
bicarbonate organic P levels were somewhat higher and ranged from 6.5 to 26.6 μg PO4-P g soil-1. Microbial P levels were the most
variable and ranged from 4.5 to 25.8 μg P04-P g soil-1. In contrast, total organic P levels were high, 149 to 348 μg P04-P g soil-1. For
the 3 years after the disturbance events, there were no significant changes in labile phosphorus pools or in total organic phosphorus
levels in the soil. This lack of significant differences is likely attributable to the low phosphorus, high P-sorbing status of the soils at
Coweeta and the lack of erosion that followed these disturbance events.
410. Wyatt, Robert; Odrzykoski, Ireneusz J.; Stoneburner, Ann. 1989. High levels of genetic variability in the haploid moss
Plagiomnium ciliare. Evolution. 43(5): 1085-1096.
Traditionally the genetic structure of mosses and liverworts is considered depauperate because bryophytes evolved more slowly than
flowering plants and have remained relatively unchanged for millions of years. Some researchers now hold that genetic variation in
bryophyte populations may be extensive because of recent discoveries of extreme diversity in biochemical, physiological, and ecological
properties of mosses and liverworts. Horizontal starch-gel electrophoresis was used to measure variability at 14 enzyme loci from 13
natural populations of the dioecious moss Plagiomnium ciliare. Overall levels of genetic polymorphism were unexpectedly high for a
haploid organism. Gene diversity was much reduced in populations from disturbed, secondary forests in the Piedmont relative to those
from minimally disturbed, primary forests in the mountains. The discovery of high levels of genetic variability in a plant with a dominant
haploid life cycle challenges the traditional view of bryophytes as a genetically depauperate group. Multiple-niche selection is proposed
as a possible explanation for this anomaly.
411. Wyckoff, Peter H.; Clark, James S. 2000. Predicting tree mortality from diameter growth: a comparison of maximum
likelihood and Bayesian approaches. Canadian Journal of Forest Research. 30: 156-167.
Ecologists and foresters have long noted a link between tree growth rate and mortality, and recent work suggests that an interspecific
difference in low growth tolerance is a key force shaping forest structure. Little information is available, however, on the growthmortality relationship for most species. We present three methods for estimating growth-mortality functions from readily obtainable
field data. All use annual morality rates and the recent growth rates of living and dead individuals. Annual mortality rates are estimated
using both survival analysis and a Bayesian approach. Growth rates are obtained from increment cores. Growth-mortality functions are
fitted using two parametric approaches and a nonparametric approach. The three methods are compared using boostrapped confidence
intervals and likelihood ration tests. For two example species, Acer rubrum L. and Cornus florida L. and Cornus florida L., growthmortality functions indicate a substantial difference in the two species' abilities to withstand slow growth. Both survival analysis and
Bayesian estimates of mortality rates lead to similar growth-mortality functions, with the Bayesian approach providing a means to
overcome the absence of long-term census data. In fitting growth-mortality functions, the nonparametric approach reveals that
inflexibility in parametric methods can lead to errors in estimating mortality risk at low growth. We thus suggest that nonparametric fits
be used as a tool for assessing parametric models.
412. Wyckoff, Peter H.; Clark, James S. 2002. The relationship between growth and mortality for seven co-occurring tree species in
the southern Appalachian mountains. Journal of Ecology. 90: 604-615.
99
Slow growth is associated with high mortality risk for trees, but few data exist to assess interspecific differences in the relationship
between growth and mortality. Here we compare low growth tolerance for seven co-occurring species in the southern Appalachian
Mountains: Acer rubrum, Betula lenta, Cornus florida, Liriodendron tulipifera, Quercus prinus, Quercus rubra, and Robinia pseudoacacia. For all species, mortality was greater for understorey individuals than for canopy trees. Species varied widely in the length of
growth decline prior to death, ranging from 6 years for L. tulipifera to more than 12 years for Q rubra. Growth-mortality functions differ
among species, but we found little evidence of a trade-off between tolerance of slow growth and an ability to show rapid growth in high
light conditions. A. rubrum stands out in its ability both to grow rapidly and to tolerate slow growth, suggesting that its density may
increase at our study site as in other parts of the eastern United States. In contrast, C. florida shows high mortality (15% per annum) as a
result of infection with dogwood anthracnose. We modified a forest simulation model, LINKAGES (which assumes that all species have
the same ability to tolerate slow growth), to include our functions relating growth and mortality. The modified model gives radically
altered predictions, reinforcing the need to rethink and re-parameterize existing computer models with field data.
413. Yeakley, J.A.; Hornberger, G.M.; Swank, W.T. 1995. Planform effects on simulated hillslope soil moisture in an upland
forested watershed. In: Singh, R.B.; Haigh, M.J., eds. Sustainable reconstruction of highland and headwater regions: Proceedings of the
third international symposium on headwater control; 1995 October 6-8; New Delhi. New Delhi: Oxford & IBH Publ: 307-316.
The effect of planform on hillslope soil moisture distribution was investigated using a terrain-fitted watershed hydrology model at the
Coweeta Hydrologic Laboratory. Soil moisture on hillslopes of contrasting planforms was simulated using a 14-year series of hourly
climate data. Mean soil moisture in 3 layers on each hill slope varied directly with PPT-PET (precipitation minus evapotranspiration).
During drought, soil moisture gradients along hillslopes increased with no significant control by planform. During recharge, however,
planform affected significant changes in soil moisture gradients between hillslopes of different planform due to persistent saturation near
the outflow of the convergent hillslope.
414. Yeakley, J.A.; Meyer, J.L.; Swank, W.T. 1994. Hillslope nutrient flux during near-stream vegetation removal I. A multi-scaled
modeling design. Water, Air and Soil Pollution. 77: 229-246.
At the Coweeta Hydrologic Laboratory in the southern Appalachians of western North Carolina, a near-stream vegetation manipulation
experiment is being conducted to determine the effect of removal of streamside Rhododendron maximum L. on the export of hillslope
nutrients (K, Na, Ca, Mg, N, P, S) and organic matter. Experimental hillslope transects that span topographical flowpaths from a local
highpoint to the stream have been instrumented with lysimeters and TDR rods at two depths, as well as with streambed and streambank
piezometers. We present a review of studies of nutrient flux in the riparian zone of forested watersheds. In the southern Appalachians,
we hypothesize that R. maximum is a keystone species at the interface between terrestrial and aquatic systems, with extensive nearstream thickets having a possible impact on carbon and nutrient transport into streams. We present the conceptual basis and initial
implementation of a model-based experimental design to test the effect of R. maximum removal on hillslope nutrient and organic matter
export in upland watersheds. The model is terrain-based and will be used to extrapolate elemental flux measurements both spatially
from the hill slope to watershed scale and temporally for various climate regimes. The model consists of three modules: (1) objective
terrain analysis (TAPES-C); (2) a dynamic interception canopy module; (3) a hillslope hydrology module (IHDM4) with a 2-D Richard's
equation of subsurface moisture dynamics. Calibration and validation of the model will occur at two scales: at the hillslope scale, using
well, lysimeter, and TDR data; at the watershed scale, using streamflow measurements across a variety of storm types. We show
watershed terrain analysis for the experimental watershed (WS56) and discuss use of the model for understanding effects of watershed
management of riparian zone processes.
415. Yeakley, J.A.; Swank, W.T.; Swift, L.W.; Hornberger, G.M.; Shugart, H.H. 1998. Soil moisture gradients and controls on a
southern Appalachian hillslope from drought through recharge. Hydrology and Earth System Sciences. 2(1): 41-49.
Soil moisture gradients along hillslopes in humid watersheds, although indicated by vegetation gradients and by studies using models,
have been difficult to confirm empirically. While soil properties and topographic features are the two general physiographic factors
controlling soil moisture on hillslopes, studies have shown conflicting results regarding which factor is more important. The relative
importance of topographic and soil property controls was examined in an upland forested watershed at the Coweeta Hydrologic
Laboratory in the southern Appalachian mountains. Soil moisture was measured along a hillslope transect with a mesic-to-xeric forest
vegetation gradient over a period spanning precipitation extremes. The hillslope transect was instrumented with a time domain
reflectometry (TDR) network at two depths. Soil moisture was measured during a severe autumn drought and subsequent winter
precipitation recharge. In the upper soil depth (0-30 cm), moisture gradients persisted throughout the measurement period, and
topography exerted dominant control. For the entire root zone (0-90 cm), soil moisture gradients were found only during drought.
Control on soil moisture was due to both topography and storage before drought. During and after recharge, variation in soil texture and
horizon distribution exerted dominant control on soil moisture content in the root zone (0-90 cm). These results indicate that topographic
factors assert more control over hillslope soil moisture during drier periods as drainage progresses, while variation in soil water storage
properties are more important during wetter periods. Hillslope soil moisture gradients in southern Appalachian watersheds appear to be
restricted to upper soil layers, with deeper hillslope soil moisture gradients occurring only with sufficient drought.
416. Yeakley, J. Alan; Moen, Ron A.; Breshears, David D.; Nungesser, Martha K. 1994. Response of North American ecosystem
models to multi-annual periodicities in temperature and precipitation. Landscape Ecology. (9) 4: 249-260.
100
Ecosystem models typically use input temperature and precipitation data generated stochastically from weather station means and
variances. Although the weather station data are based on measurements taken over a few decades, model simulations are usually on the
order of centuries. Consequently, observed periodicities in temperature and precipitation at the continental scale that have been
correlated with large-scale forcings, such as ocean-atmosphere dynamics and lunar and sunspot cycles, are ignored. We investigated how
these natural climatic fluctuations affect aboveground biomass in ecosystem models by incorporating some of the more pronounced
continental-scale cycles in temperature (4,11, 80,180 year periods) and precipitation (11 and 19 year periods) into models of three North
American forests (using LINKAGES) and one North American grassland (using STEPPE). Even without inclusion of periodicities in
climate, long-term dynamics of these models were characterized by internal frequencies resulting from vegetation birth, growth, and
death processes. Our results indicate that long-term temperature cycles result in significantly lower predictions of forest biomass than
observed in the control case for a forest on a biome transition (northern hardwoods/boreal forest). Lower-frequency, higher-amplitude
temperature oscillation caused amplification of forest biomass response in forests containing hardwood species. Shortgrass prairie and
boreal ecosystems, dominated by species with broad stress tolerance ranges, were relatively insensitive to climatic oscillations. Our
results suggest periodicities in climate should be incorporated within long-term simulations of ecosystems with strong internal
frequencies, particularly for systems on biome transitions.
417. Yeakley, J. Alan; Coleman, David C.; Haines, Bruce L.; Kloeppel, Brain, D.; Meyer, Judy L.; Swank, Wayne T.; Argo,
Barry W.; Deal, James M.; Taylor, Sharon F. 2003. Hillslope nutrient dynamics following upland riparian vegetation disturbance.
Ecosystems. 6(2): 154-167.
We investigated the effects of removing near-stream Rhododendron and of the natural blowdown of canopy trees on nutrient export to
streams in the southern Appalachians. Transects were instrumented on adjacent hillslopes in a first-order watershed at the Coweeta
Hydrologic Laboratory (35degrees03'N, 83degrees25'W). Dissolved organic carbon (DOC), K+, Na+, Ca2+, Mg2+, NO3--N, NH4+-N,
PO43--P, and SO42- were measured for 2 years prior to disturbance. In August 1995, riparian Rhododendron on one hillslope was cut,
removing 30% of total woody biomass. In October 1995, Hurricane Opal uprooted nine canopy trees on the other hillslope, downing
81% of the total woody biomass. Over the 3 years following the disturbance, soilwater concentrations of NO3--N tripled on the cut
hillslope. There were also small changes in soilwater DOC, SO42-, Ca2+, and Mg2+. However, no significant changes occurred in
groundwater nutrient concentrations following Rhododendron removal. In contrast, soilwater NO3--N on the storm-affected hillslope
showed persistent 500-fold increases, groundwater NO3--N increased fourfold, and streamwater NO3--N doubled. Significant changes
also occurred in soilwater pH, DOC, SO42-, Ca2+, and Mg2+. There were no significant changes in microbial immobilization of soil
nutrients or water outflow on the storm-affected hillslope. Our results suggest that Rhododendron thickets play a relatively minor role in
controlling nutrient export to headwater streams. They further suggest that nutrient uptake by canopy trees is a key control on NO3--N
export in upland riparian zones, and that disruption of the root-soil connection in canopy trees via uprooting promotes significant nutrient
loss to streams.
418. Zak, Donald R.; Tilman, David; Parmenter, Robert R.; Rice, Charles W.; Fisher, Frederick M.; Vose, James; Milchunas,
Daniel; Martin, C. Wayne. 1994. Plant production and soil microorganisms in late-successional ecosystems: a continental-scale study.
Ecology. 75(8): 2333-2347.
Annual C inputs from plant production in terrestrial ecosystems only meet the maintenance energy requirements of soil microorganisms,
allowing for little or no net annual increase in their biomass. Because microbial growth within soil is limited by C availability, we
reasoned that plant production should control the biomass of soil microorganisms. We also reasoned that soil texture should further
modify the influence of plant production on soil C availability because fine-textured soils typically support more microbial biomass than
coarse-textured soils. To test these ideas, we quantified the relationship between aboveground net primary production (ANPP) and soil
microbial biomass in late-successional ecosystems distributed along a continent-wide gradient. We also measured labile pools of C and
N within the soil because they represent potential substrate for microbial activity. Ecosystems ranged from a Douglas-fir forest in the
western United States to the grasslands of the mid-continent to the hardwood forests in the eastern U.S. Microbial biomass C displayed a
positive, linear relationship with ANPP, but was not significantly related to soil texture. Labile C also was linearly related to ANPP and
to soil texture. Results indicate that microbial biomass and labile organic matter pools change predictably across broad gradients of
ANPP, supporting the idea that microbial growth in soil is constrained by C availability.
419. Adams, Janey C. 1998. The role of leaf litter and small wood in the retention of fine particles during storms in an Appalachian
headwater stream. Blacksburg, VA: Virginia Polytechnic Institute and State University. 96 p. M.S. thesis.
420. Addington, Robert Norris. 2001. Water use patterns and stomatal responses to environment in longleaf pine on contrasting
sites. Athens, GA: University of Georgia. 68 p. M.S. thesis.
421. Argo, Barry Wayne. 1998. Macroclimate and microclimate effects on flowering phenology and habitat distribution of
Caulophyllum (Berberidaceae) in the southern Appalachian mountains. Athens, GA: University of Georgia. 78 p. M.S. thesis.
422. Baker, Terrell T. 1994. The Influence of Rhododendron Maximum on species richness in the riparian ecosystem of Wine Spring
Creek. Clemson, SC: Clemson University. 93 p. M.S. thesis.
101
423. Bathala, Neeti. 2004. The effects of nitrogen and phosphorus on fine roots and mycorrhizae across different taxonomic groups,
mycorrhizal types and biomes. Athens, GA: University of Georgia. 118 p. Ph. D. dissertation.
424. Beckage, Brian. 2000. (Ecology) Seedling recruitment in southern Appalachian forests: Does spatial heterogeneity maintain
species diversity? Durham, NC: Duke University. 179 p. Ph.D. dissertation.
425. Beckage, Brian. 2000. A long-term study of red maple (ACER RUBRUM L.) seedling survival in southern Appalachian forests:
The effects of canopy gaps and shrub understories. Durham, NC: Duke University. 34 p. M.S. thesis.
426. Bennett, Barbara Loraine. 1998. Land use influences on benthic invertebrate assemblages in southern Appalachian agricultural
streams. Blacksburg, VA: Virginia Polytechnic Institute and State University. 96 p. M.S. thesis.
427. Bonito, Gregory M. 2001. Factors regulating nitrogen mineralization rates of an oak pine and hardwood forest along an
elevation gradient. Athens, GA: University of Georgia. 112 p. M.S. thesis.
428. Bryan, Debra Sue. 1994. Factors controlling the occurrence and distribution of hematite and goethite in soils and saprolites
derived from schists and gneisses in western North Carolina. East Lansing, MI: Michigan State University. 125 p. M.S. thesis.
429. Cargo, Dale M. 1996. Factors controlling export of suspended sediments from two-second order southern Appalachian mountain
stream watersheds. Durham, NC: Nicholas School of the Environment, Duke University. 30 p. Master of Environmental Management
thesis.
430. Carlile, Lawrence Dean. 1994. Breeding songbird populations on experimental watersheds and pitch pine gaps at the Coweeta
Hydrologic Laboratory, North Carolina. Athens, GA: University of Georgia. 67 p. M.S. thesis.
431. Clark, Sherri Havert. 1990. A study of factors controlling the isotopic composition of water within a forested watershed.
Athens, GA: University of Georgia. 98 p. M.S. thesis.
432. Collins, Fred C. Jr. 1996. A comparison of spatial interpolation techniques in temperature estimation. Blacksburg, VA: Virginia
Polytechnic Institute and State University. 234 p. Ph.D. dissertation.
433. Cooley, Nicolette E. 2004. Understanding traditional knowledge for ecological restoration: a qualitative study with the Eastern
Band of Cherokee. Flagstaff, AZ. Northern Arizona University. 71 p. M.S. thesis.
434. Davis, Jonathan Paul. 1998. Fine root dynamics along an elevational gradient in the southern Appalachian mountains, USA.
Athens, GA: University of Georgia. 83 p. M.S. thesis.
435. Dlamini, Eunice T. 1990. Pinus strobus needle ethanol-soluble proline and ethanol-insoluble protein contents of air- and ozonefumigated new foliage. Atlanta, GA: Clark-Atlanta University. 41 p. M.S. thesis.
436. Dobbs, Marion McNamara. 1995. Spatial and temporal distribution of the evergreen understory in the southern Appalachians.
Athens, GA: University of Georgia. 104 p. M.S. thesis.
437. Dobbs, Marion McNamara. 1998. Dynamics of the evergreen understory at Coweeta Hydrologic Laboratory, North Carolina.
Athens, GA: University of Georgia. 179 p. Ph.D. dissertation.
438. Eggert, Susan Lynn. 2003. Resource use by detritivorous macroinvertebrates in southern Appalachian headwater streams.
Athens, GA: University of Georgia.257 p. Ph.D. dissertation.
439. Fettinger, Jennifer L. 2002. Ruffed grouse nesting ecology and brood habitat in western North Carolina. Knoxville, TN:
University of Tennessee. 105 p. M.S. thesis.
440. Gardiner, Edward P. 1995. Scale-dependent heterogeneity of soil properties at Coweeta. Athens, GA: University of Georgia.
132 p. M.S. thesis.
441. Gardiner, Edward P. 2002. Geospatial techniques for stream research in the southern Blue Ridge Mountains. Athens, GA.:
University of Georgia. 195 p. Ph.D. dissertation.
102
442. Griffith, Converse, Jr. 1993. Relations between leaf nutrient concentrations and mineralization rates along an elevational
gradient in the southeastern Appalachians, USA. Athens, GA: University of Georgia. 139 p. M.S. thesis.
443. Grubaugh, Jack William. 1994. Influences of elevation, stream size, and land use on structure, function, and production of
benthic macroinvertebrate communities in two southern river ecosystems. Athens, GA: University of Georgia. 171 p. Ph.D dissertation.
444. Hagen, Elizabeth Mary. 2004. Influence of agricultural land use on allochthonous input and leaf breakdown in southern
Appalachian streams. 94 p. M.S. thesis.
445. Hall, Constance Susan. 1978. Modification of nonpoint source pollutant loading (NPS) model. Clemson, SC: Clemson
University. 36 p. M.S. thesis.
446. Hall, Robert Ogden, Jr. 1996. Bacterivory and organic matter flow in stream food webs. Athens, GA: University of Georgia.
184 p. Ph.D dissertation.
447. Harper, Craig Andrew. 1998. Analysis of wild turkey brood habitat within the southern Appalachians. Clemson, SC: Clemson
University. 166 p. Ph.D. dissertation.
448. Henson, Mickey B. 1994. Estimating the bankfull event in small watersheds of the southern Appalachian Mountains. Clemson,
SC: Clemson University. 45 p. M.S. thesis.
449. HilleRisLambers, Janneke. 2001. Dormancy, dispersal, and density-dependent mortality: Coexistence of temperate forest tree
species. Durham, NC: Duke University. 184 p. Ph.D. dissertation.
450. Hoffman, Richard Rainey. 1994. Stream morphology and equilibrium: the magnitude and frequency of geomorphically
effective events. Hanover, NH: Dartmouth College. 72 p. Honors thesis.
451. Hoover, Coeli Marie. 1996. Microarthropod community structure and nutrient dynamics in decomposing leaf litter: an
altitudinal gradient study at the Coweeta Hydrologic Laboratory. Athens, GA: University of Georgia. 175 p. Ph.D. dissertation.
452. Hutchens, John Jehu, Jr. 1994. The diet and growth of a leaf-shredding caddisfly, Pycnopsyche, in streams of contrasting
disturbance histories. Blacksburg, VA: Virginia Polytechnic Institute and State University. 69 p. M.S. thesis.
453. Hutchens, John Jehu, Jr. 2000. Effects of geomorphology and disturbance on stream ecosystems in the southern Appalachians.
Athens, GA: University of Georgia: 238 p. Ph.D. dissertation.
454. Katz, Robert T. 1997. Using landscape ecosystem classification to manage neotropical migratory birds in the mountains of
western North Carolina. Clemson, SC: Clemson University. 96 p. M.S. thesis.
455. Lambiase, Seth J. 1999. Interspecific life history variation in the land snail genus Mesodon. Chapel Hill, NC: University of
North Carolina at Chapel Hill. 104 p. M.S. thesis.
456. Lamoncha, Karen L. 1994. Spatial and temporal variation in diversity of soil oribatida in Southeastern Appalachian Forests.
Athens, GA: University of Georgia. 224 p. M.S. thesis.
457. Lanford, Jonathan Eugene. 1991. Diversity and community structure of forest floor macroarthropods at Coweeta with special
reference to ants and carabids. Athens, GA: University of Georgia. 107 p. M.S. thesis.
458. Madson, Stephanie Lee. 2003. Response of soil microarthropods and microclimatic conditions to two-age regeneration in
hardwood forests in the southern Appalachians. Athens, GA: University of Georgia. 98 p. Ph.D. dissertation.
459. Major, Amy Elizabeth. 1996. The effects of stand-replacement fires on pine and oak communities in the southern
Appalachians. Athens, GA: University of Georgia. 89 p. M.S. thesis.
460. McTammany, Matthew Eric. 2004. Recovery os southern Appalachian streams from historical agriculture. Blacksburg, VA:
Virginia Polytechnic Institute and State University. 145 p. Ph. D. dissertation.
461. McTammany, Matthew Eric. 1998. The impact of urbanization on benthic macroinvertebrates in southern Appalachian streams.
Blacksburg, VA: Virginia Polytechnic Institute and State University. 90 p. M.S. thesis.
103
462. Neihardt, Charlene. 1999. Water quality monitoring at the watershed scale using subpixel analysis and benthic
macroinvertebrates. Clemson, SC: Clemson University. 87 p. M.S. thesis.
463. Olson, Matthew Scott. 1997. The genetics and evolution of subdioecy in Astilbe Biternata. Durham, NC: Duke University. 197
p. Ph.D. dissertation.
464. Parr, Mark William. 1992. Long-term vegetation response to thinning in a southern Appalachian cove. Athens, GA: University
of Georgia. 126 p. M.S. thesis.
465. Paul, Michael John. 1994. Fungal biomass in an Appalachian stream. Athens, GA: University of Georgia. 94 p. M.S. thesis.
466. Petty, Jeffrey Todd. 1998. Mottled sculpin in a dynamic landscape: linking environmental heterogeneity, individual behaviors,
and population dynamics in a southern Appalachian stream. Athens, GA: University of Georgia. 156 p. Ph.D. dissertation.
467. Petty, Jeffrey Todd. 1994. Patch selection by a predatory, benthic stream fish: the role of macroinvertebrate distribution.
Athens, GA: University of Georgia. 57 p. M.S. thesis.
468. Powell, Natalie Lyn. 2001. The role of crayfish in leaf decomposition across a range in litter quality. Athens, GA: University of
Georgia. 63 p. M.S. thesis.
469. Price, Jason R. 2003. Allanite weathering and rare earth elements in mass balance calculations of clay genesis rates at the
balance calculations of clay genesis rates at the Coweeta Hydrologic Laboratory, western North Carolina, USA: The response times of
changes in clay mineral assemblages to fluctuations in climate. East Lansing, MI: Michigan State University. 237 p. Ph.D. dissertation.
470. Rachel, Gary. 2004. The vertical distribution arbuscular, ericoid, and ectomycorrhizae in a forest soil: correlations with soil and
P distribution and root topology. Athens, GA: University of Georgia. 119 p. Ph.D. dissertation.
471. Reynolds, Barbara Foster. 2000. Effects of canopy herbivores on soil systems along an elevation gradient. Athens, GA:
University of Georgia. 133 p. Ph.D. dissertation.
472. Reynolds, Barbara Foster. 1995. Elevation effects on forest canopy insect herbivory in southern Appalachian hardwood forests.
Athens, GA: University of Georgia. 85 p. M.S. thesis.
473. Romitelli, Maria Silvia. 1997. Energy analysis of watersheds. Gainesville, FL: University of Florida. 292 p. Ph.D. dissertation.
474. Rosi, Emma Josephine. 1994. The trophic basis of production along a river continuum: temporal and spatial variability in the
flow of energy in aquatic macroinvertebrate communities. Athens, GA: University of Georgia: 82 p. M.S. thesis.
475. Rosi-Marshall, Emma Josephine. 2002. Quality of suspended fine particulate matter and its role as a conduit for metals In
Riverine Food Webs. Athens, GA: University of Georgia. 154 p. Ph.D. dissertation.
476. Sanchez de Boado, Alexi P. 1999. Regional scale analysis of select controls of dissolved inorganic nitrogen loss from five
hardwood ecosystems in the eastern US. Syracuse, N.Y.: State University of New York. 161 p. M.S. thesis.
477. Sankovski, Alexei Georgievich. 1994. Diversity and structure of southern Appalachian and southwestern Caucasus forests with
respect to historical events and present environment. Athens, GA: University of Georgia. 212 p. Ph.D. dissertation.
478. Schaeffer, Mary Alice. 1993. Effects of land use on oxygen uptake by microorganisms on fine benthic organic matter in two
Appalachian mountain streams. Blacksburg, VA: Virginia Polytechnic Institute and State University. 71 p. M.S. thesis.
479. Schofield, Katherine Ann. 2002. Top-down interactions in southern Appalachian streams: An examination of temporal and
spatial variability. Athens, GA. University of Georgia. 237 p. Ph.D. dissertation.
480. Schumacher, Carrie L. 2002. Ruffed grouse habitat use in western North Carolina. Knoxville, TN; University of Tennessee. 73
p. M.S. thesis.
481. Scott, Mark Chandler. 2001. Integrating the stream and its valley: land use change, aquatic habitat, and fish assemblages.
Athens, GA: University of Georgia. 166 p. Ph.D. dissertation.
104
482. Sponseller, Ryan Allen. 2000. Influences of land use on the structure and function of headwater streams: A multiple scale
analysis. Blacksburg, VA: Virginia Polytechnic Institute and State University. 79 p. M.S. thesis.
483. Sutherland, Andrew Bryan. 1998. Effects of land-use change on sediment regime and fish assemblages in the upper Little
Tennessee River. Athens, GA: University of Georgia. 158 p. M.S. thesis.
484. Tank, Jennifer Leah. 1996. Microbial activity on wood in streams: exploring abiotic and biotic factors affecting the structure
and function of wood biofilms. Blacksburg, VA: Virginia Polytechnic Institute and State University. 175 p. Ph.D. dissertation.
485. Tilley, David Rogers. 1999. Emergy basis of forest systems. Gainesville, FL: University of Florida. 296 p. Ph.D. dissertation.
486. Turner, Patricia Anne. 1994. Macroinvertebrate drift along an elevational and stream size gradient in a southern Appalachian
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487. Vila, Peter Benjamin. 1996. Size structure of the zoobenthos in headwater streams: meiofaunal-macroinvertebrate interactions.
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488. Wagner, C. Michael. 2004. An experimental study of foraging aggression in two southeastern minnows: implications for an
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489. Wagner, Paul F. 2001. Legacies of early 20th. Century logging in southern Appalachian streams. Blacksburg, VA: Virginia
Polytechnic Institute and State University. 203 p. Ph D. dissertation.
490. Walker, John F. 1998. The inhibitory effect of Rhododendron maximum L. (Ericaceae) Thickets on mycorrhizal colonization of
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491. Ward, Brian Richard. 1996. Effects of discharge and substrate characteristics on FPOM retention. Blacksburg, VA: Virginia
Polytechnic Institute and State University. 76 p. M.S. thesis.
492. Waterman, Jayson Ralph. 1994. Ecophysiology and gap dynamics in pitch pine - mountain laurel communities in the southern
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493. Wright, Christina Jane. 1998. The effects of man-made and natural disturbance events upon soil microbial biomass, soil fauna,
soil nutrient cycling, and litter decomposition in the southern Appalachians. Athens, GA: University of Georgia. 186 p. Ph.D.
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494. Wyckoff, Peter Howard. 1999. Growth and mortality of trees in the southern Appalachian Mountains. Durham, NC: Duke
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495. Wohl, Debra Leslie. 1994. Benthic macroinvertebrate community structure along a southern Appalachian stream continuum:
the influence of spatial scale. Athens, GA: University of Georgia. 89 p. M.S. thesis.
496. Zipp, Roy Mason. 1997. Composition, abundance, and biomass of macroinvertebrate drift in a southern Appalachian creek.
Durham, NC: Nicholas School of the Environment, Duke University. 43 p. Master of Environmental Management thesis.
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