Download HABITAT DESCRIPTIONS: UPLAND HABITATS

Hudsonia Ltd.
a nonprofit institute
Habitats and Rare Plants
at the Proposed “Dover Knolls” Development Site,
Town of Dover, Dutchess County, New York:
Existing Conditions
Report prepared for Michael W. Klemens, LLC
By John Sullivan, Gretchen Stevens, Spider Barbour, and Erik Kiviat
Hudsonia Ltd.
PO Box 5000, Annandale, NY 12504
February 2005
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CONTENTS
Page
INTRODUCTION
Background……………………………….…………………………….……… 5
Study Area……………………………..…………………………….………… 6
METHODS
Habitat Identification and Mapping………………..…………………………... 8
Rare Plant Survey……………………………………………………………….9
RESULTS
Habitats………………………………………………………………………… 10
Upland Forest………………………………………………………….…… 10
Marble Knoll……………………………………………………………….. 15
Red Cedar Woodland……………………………………………….……… 18
Shrubby Oldfield……………………………………………………………20
Upland Meadow……………………………………………………………. 21
Oak-Heath Barren………………………………………………………….. 23
Crest, Ledge, and Talus……………………………………………………..25
Calcareous Crest, Ledge, and Talus………………………………………... 26
Waste Ground………………………………………………………….……28
Cultural……………………………………………………………………...28
Hardwood & Shrub Swamp………………………………………………... 29
Emergent Marsh………………………………………………………….… 31
Fen…………………………………………………………………………. 33
Wet Meadow……………………………………………………………….. 36
Calcareous Wet Meadow…………………………………………………... 37
Intermittent Woodland Pool………………………………………….…….. 38
River………………………………………………………………………... 41
Constructed Pond…………….………………………………………….…. 41
Intermittent and Perennial Stream………..…………………………………42
Springs and Seeps…………………………………………………….……. 43
Rare Plants……...……………………………………………………………… 45
(continued)
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CONTENTS (cont.)
DISCUSSION
Eastern Hills…………………………………………………………………….49
Fens………………………………………………………………………..…… 51
Marble Knolls………………………………………………………………….. 51
Swamp River/Great Swamp………………………………………………….… 52
Intermittent Woodland Pools……………………………………………….….. 52
Summary Recommendations…………………………………………………... 53
REFERENCES CITED……………………………………………...……….…... 54
APPENDIX A: Explanation of ranks of species of conservation concern……..… 57
APPENDIX B: Qualifications of Hudsonia personnel…………………………….. 58
FIGURES
1. Study Site Location..…………………………………………………..…... 59
2a. Habitats west of Route 22…………………………….……………………. 60
2b. Habitats east of Route 22…………………………….……………...…...… 61
TABLES
1. Daily rare plant survey effort of Barbour at the “Dover Knolls” site, 2004... 9
2. Rare plants found at the “Dover Knolls” study site, 2004………………….. 48
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INTRODUCTION
INTRODUCTION
BACKGROUND
Hudsonia was retained by Michael W. Klemens LLC to conduct a rare plant survey and to
identify and map habitats throughout the proposed “Dover Knolls” development site, on and
near the property of the former Harlem Valley Psychiatric Center (HVPC) at the hamlet of
Wingdale, Town of Dover, Dutchess County, New York. This report describes existing
conditions at the site, without reference to proposed development on any part of the site.
Hudsonia Ltd. is an independent, non-advocacy, not-for-profit institute for research and
education in the environmental sciences. Hudsonia conducts pure and applied research on
natural and social science aspects of the environment, offers technical assistance to public
and private agencies and individuals, provides instruction in assessment and planning for
biodiversity conservation, and produces educational publications on natural history and
conservation topics. Hudsonia does not support or oppose development proposals or land use
changes; rather, we conduct scientific studies and provide full resulting data, analysis, and
recommendations to landowners, municipal agencies, other decision-makers, and citizens. In
accordance with arrangements for scientific data exchange, copies of this report will be
provided to the New York Natural Heritage Program and the New York State Department of
Environmental Conservation Endangered Species Unit.
The Harlem Valley in general and the Town of Dover in particular have been recognized for
many years (e.g. Kiviat 1988) as especially rich areas for biological diversity. The close
juxtaposition of the marble bedrock in the valley, the acidic schist and gneiss bedrock of the
rugged hills to the east and west, the extensive wetlands associated with the Swamp River,
and the neutral to alkaline soils elsewhere in the valley all contribute to the unusual diversity
of habitats and species. Certain habitats—such as marble knoll and fen—that are rare
elsewhere in southeastern New York are concentrated in the Harlem Valley corridor, and
Dover is a well known “hotspot” for rare animals such as the bog turtle (listed as Threatened
under the federal Endangered Species Act, and as Endangered in New York State), the timber
rattlesnake (NYS Threatened), and many state-listed rare plants. In view of the recent
acceleration of land development activity in the Harlem Valley, it is especially timely to
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INTRODUCTION
assess the importance of large land parcels to maintaining native biodiversity resources in the
region.
THE STUDY AREA
The study area for this project comprises approximately 393 hectares (972 acres) straddling
NYS Route 22 at the hamlet of Wingdale. The property has nearly level areas on and
adjacent to the floodplain of the Swamp River (approximately 128 m [420 ft] elevation)
flanked by rolling hills to the west (to 165 m [540 ft] elevation) and steep, rocky hills to the
east (to 284 m [931 ft]). West of Rt. 22, the site includes a nine-hole golf course and active
and inactive agricultural land and forests, bordered on the west by Pawling Road and on the
north by Pleasant Ridge Road. East of Rt. 22, the site includes the buildings and internal
roads of the former HVPC campus, the predominantly wooded hills to the east, and a 3.6 ha
(9 ac) reservoir that formerly served the HVPC.
The study area is drained by the Swamp River which flows north to the Tenmile River, a
tributary of the Housatonic River. The site includes a portion of the Great Swamp, an
immense wetland partly on the floodplain of the Swamp River. Small unnamed tributaries to
the Swamp River drain the eastern and western portions of the study site.
The bedrock underlying the study site was mapped by Fisher et al. (1970) as predominantly
calcitic and dolomitic marble of the Stockbridge Marble formation in the low-lying areas,
and schists and amphibolite of the Manhattan Formation in the eastern hills. Thus, the
bedrock of the valley is alkaline and subject to weathering and erosion, and that of the
eastern hills is at least partly acidic and relatively hard.
The county soil survey (Faber 2002) mapped the upland soils west of Rt. 22 as a mosaic of
silt loam soils formed in glacial till or glacial outwash. The till-derived soils were mapped as
various complexes of Farmington, Galway, and Stockbridge soils, all described as strongly
acidic to moderately alkaline. The outwash soil was Copake gravelly silt loam, a strongly
acidic to moderately alkaline soil with abundant limestone fragments. Pawling silt loam, the
only upland alluvial soil on the site, is described as strongly acidic to neutral. The Great
Swamp and nearby wetlands are underlain mainly by Carlisle muck (organic) and Wayland
silt loam (alluvial), with smaller areas of Sun silt loam (till) and Raynham silt loam
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INTRODUCTION
(lacustrine) (Faber 2002). These soils are described variously as very strongly acidic to
neutral to moderately alkaline in the surface layers and subsoils. Copake, Pawling,
Stockbridge, and Raynham are considered prime farmland soils (Raynham only if drained)
(Faber 2002).
East of Rt. 22, most of the upland soils are derived from glacial till (Faber 2002). The soils of
the steepest areas were mapped as Chatfield and Hollis soil complexes (very strongly to
moderately acidic), some with rock outcrops. Stockbridge silt loam was predominant on the
gentler side slopes. Here and there were smaller areas of Stockbridge-Farmington, Massena
silt loam, Charlton loam, and Copake silt loam. Soils of the large wetlands in the eastern hills
were mapped as Sun silt loam, a very deep, strongly acidic to moderately alkaline soil. The
soils of small wetlands were not mapped by Faber (2002).
East of Rt. 22, a few buildings were in active use, but most were vacant. The lawns of the
former HVPC campus were mowed. There was evidence of all-terrain-vehicle (ATV) use of
the network of gravel roads in the forested hills east of the campus. West of Rt. 22, a ninehole golf course and the cornfields represented the primary active land uses. Abandoned
fields, upland forests, and swamps comprised the remaining areas in the western part of the
study site.
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METHODS
METHODS
All work on the project was supervised by Erik Kiviat and Gretchen Stevens. Field surveys
were conducted by Kiviat, Stevens, John Sullivan, and Spider Barbour. All workers
contributed to the report and the map. Qualifications of Hudsonia personnel are given in
Appendix B.
HABITAT IDENTIFICATION AND MAPPING
We identified ecologically significant habitats using methods and criteria adapted from
Kiviat and Stevens (2001), but included several additional habitats not profiled in that
document. We made preliminary habitat predictions by analysis of topographic, soil, and
bedrock geology maps, and by stereo interpretation of aerial photographs. We digitized the
habitat boundaries over digital orthophotos images using ArcView 3.2 GIS software.
We used the following map and aerial photograph resources:
•
US Geological Survey 7.5 minute Dover Plains, NY, topographic map quadrangle
from 1958 (photorevised 1984).
•
Geologic Map of New York, Lower Hudson Sheet. Map and Chart Series 15.
1:250,000, 100 ft contour. New York State Museum and Science Service, Albany
(Fisher et al. 1970).
•
Soil Survey of Dutchess County, New York (Faber 2002).
•
1:40,000 scale color infrared aerial photograph prints from the National Aerial
Photography Program series taken in April 1994, obtained from the US Geological
Survey.
•
High-resolution (1 pixel = 7.5 in [19 cm]), true-color digital orthophotos (NY State
Plane, NAD 83, units of feet), taken spring 2000, obtained from the Dutchess County
Office of Real Property Tax.
We checked in the field as many locations as possible to correct and refine the preliminary
map. We produced the final habitat map in a small format (figures 2a and 2b) at 1:10,000
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METHODS
scale for this report using a Samsung CLP 500 laser printer, and in a large format at 1:4,500
scale for public presentation using an HP DesignJet 800 PS plotter.
Sullivan conducted the preliminary (remote) habitat identification and mapping, and the map
was corrected, verified, and refined on the basis of field observations by Sullivan, Barbour,
Kiviat, and Stevens.
RARE PLANT SURVEY
We conducted field surveys for rare plants in mid-spring, late spring-early summer, midsummer, and late summer in selected habitats. We collected voucher specimens of each rare
species, and recorded local habitat information. Voucher specimens have been deposited at
the Bard College Field Station Herbarium. For occurrences without nearby permanent
landmarks, we obtained UTM coordinates using a Garmin E-Trex GPS unit. The rare plant
survey focused especially on the marble knolls, calcareous wetlands, calcareous upland
forests, the Swamp River and its floodplain swamp, the ravine below the reservoir, and an
intermittent woodland pool northeast of the reservoir. The survey was conducted mainly by
Spider Barbour; Sullivan, Kiviat, and Stevens also contributed rare plant observations.
Barbour’s total survey effort at the “Dover Knolls” site was approximately 58 hours. Table 1
summarizes Barbour’s approximate survey effort for each survey day.
Table 1. Daily rare plant survey effort of Barbour
at the “Dover Knolls” site, 2004.
Survey Date
May 14, 2004
June 2, 2004
June 4, 2004
June 16, 2004
June 30, 2004
July 21, 2004
August 20, 2004
September 1, 2004
September 22, 2004
October 8, 2004
Approximate
Survey effort
(hrs)
6
6
6
6
6
6
4
6
6
6
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RESULTS: HABITAT DESCRIPTIONS
RESULTS
HABITATS
The habitats identified on the site are mapped in figures 2a and 2b, and on the large-format
map sheet separate from this report. Each habitat type, its occurrence on the site, and some
aspects of the conservation importance of the habitat are briefly described below. We
conducted no wildlife surveys on the study site, but the descriptions here include some
discussion of potential species of conservation concern that may occur in these habitats.
Klemens (2005) and Miller (2005) report on reptile, amphibian, and bird surveys conducted
in spring and summer 2004.
The habitat map was prepared largely by remote sensing, with field observations at selected
locations. The boundaries of habitats shown on the map are only approximate, and thus the
habitat map is useful for general site planning but not for detailed site design. Wherever the
exact location of a boundary is needed, the boundary must be identified in the field by a
qualified person, and surveyed by a land surveyor.
The map codes used in the large-format map are given in abbreviations in parentheses
following the habitat name below. The rarity ranks of species (e.g. NYS Threatened,
regionally rare) are explained in Appendix A.
UPLAND FORESTS (udf, umf, ucf)
Ecological Attributes
We mapped three general types of upland forest habitat in the study area: upland deciduous
forest, upland mixed forest, and upland conifer forest. Each of these is described below.
Upland Deciduous Forest (udf)
Deciduous forests on the site varied considerably in species composition depending on
landscape position, soil characteristics, and disturbance history. Recently disturbed areas
were dominated by various early successional and non-native tree species such as black
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RESULTS: HABITAT DESCRIPTIONS
locust (Robinia pseudo-acacia), black cherry (Prunus serotina), white ash (Fraxinus
americana), green ash (F. pennsylvanica), eastern cottonwood (Populus deltoides), black
walnut (Juglans nigra), and sugar maple (Acer saccharum). The shrub layer was typically
dense with common buckthorn (Rhamnus cathartica), Bell’s honeysuckle (Lonicera x bella),
multiflora rose (Rosa multiflora), Japanese barberry (Berberis thunbergii), tree-of-heaven
(Ailanthus altissima), and gray dogwood (Cornus foemina ssp. racemosa). Other “weedy”
species such as garlic mustard (Alliaria petiolata), poison ivy (Toxicodendron radicans),
Virginia creeper (Parthenocissus quinquefolia), and Oriental bittersweet (Celastrus
orbiculatus) were common in the ground layer.
Areas of upland deciduous forest that were less disturbed, either due to steep topography or
remote location, were characterized by a more mature forest community. These forests
contained a diverse and variable mixture of hardwoods with sugar maple, red oak (Quercus
rubra), chestnut oak (Q. montana), black oak (Q. velutina), pignut hickory (Carya glabra),
shagbark hickory (C. ovata), and black birch (Betula lenta) among the co-dominants. The
shrub layer was also moderately diverse but patchy in distribution, with mapleleaf viburnum
(Viburnum acerifolium), seedlings and saplings of various oaks and hickories, witch hazel
(Hamamelis virginiana), lowbush blueberry (Vaccinium pallidum), spicebush (Lindera
benzoin), striped maple (Acer pensylvanicum), alternate-leaf dogwood (Cornus alternifolia),
and common shadbush (Amelanchier arborea) among the typical species. Other shrubs such
as mountain laurel (Kalmia latifolia) and highbush blueberry (Vaccinium corymbosum) were
abundant on the steepest northwest facing slopes and rocky summit areas. An uncommon
component of the shrub layer in a few locations was American chestnut (Castanea dentata),
once an important co-dominant tree in this region that now exists only as sprouts or young
trees due to the chestnut blight that arrived in the early 1900s. Forest wildflowers were
diverse; some common species were white wood aster (Aster divaricatus), wild sarsaparilla
(Aralia nudicaulis), wild geranium (Geranium maculatum), Canada mayflower
(Maianthemum canadense), white baneberry (Actaea pachypoda), large-leaved aster (Aster
macrophyllus), wild columbine (Aquilegia canadensis), purple trillium (Trillium erectum),
and bloodroot (Sanguinaria canadensis). Christmas fern (Polystichum acrostichoides),
marginal shield fern (Dryopteris marginalis), common wood fern (D. intermedia), and New
York fern (Thelypteris noveboracensis), along with several sedges (e.g. Carex pensylvanica,
C. albicans var. albicans), were also locally abundant in the higher quality upland deciduous
forest habitat.
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RESULTS: HABITAT DESCRIPTIONS
A band of exceptionally diverse deciduous forest occurred along the walls of the ravine
below the reservoir. Because of the cool, moist, and shaded conditions, this ravine supported
a rich assortment of species that were absent or uncommon elsewhere at the site. Large tulip
trees (Liriodendron tulipifera), (38-50 cm [15-20 in] diameter-at-breast-height [dbh]), shared
the upper canopy with yellow birch (Betula alleghaniensis), American basswood (Tilia
americana), American beech (Fagus grandifolia), and several other species listed above.
Eastern hemlock (Tsuga canadensis) was moderately abundant, but small (less than 15 cm [6
in] dbh) and confined to the sub-canopy. Unusual species in the shrub layer included bushhoneysuckle (Diervilla lonicera), leatherwood (Dirca palustris), round leaf dogwood
(Cornus rugosa), and sassafras (Sassafras albidum). The ground layer had zigzag goldenrod
(Solidago flexicaulis), blue-stemmed goldenrod (S. caesia), spikenard (Aralia racemosa),
wild ginger (Asarum canadense), Bishop’s cap (Mitella diphylla), horse balm (Collinsonia
canadensis), toothwort (Dentaria diphylla), maidenhair fern (Adiantum pedatum), bulblet
bladder fern (Cystopteris bulbifera), lady fern (Athyrium filix-femina), rattlesnake fern
(Botrychium virginianum), and at least nine sedge species including plantain sedge (Carex
plantaginea), C. digitalis, C. blanda, and C. platyphylla.
Although it possesses a number of characteristics similar to those of the “cool ravine” habitat
described by Kiviat and Stevens (2001), this ravine is not cool enough and the slopes not
rocky enough to be classified as a “cool ravine.” This area was therefore included within the
upland deciduous forest habitat. Due to its potential ecological significance, however, we
mapped this area with a special overlay on the habitat map.
Upland Mixed forest (umf)
The term “upland mixed forest” refers to upland forests dominated by a mixture of
coniferous and deciduous trees, but where neither represents greater than 75 percent of the
canopy. Mixed forests on the site were composed of various hardwood species mentioned
above and at least one of the following conifers: white pine (Pinus strobus), eastern hemlock,
and eastern red cedar (Juniperus virginiana). Although these areas were slightly more shaded
than pure deciduous forests, they still tended to support a moderately diverse array of
understory species.
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RESULTS: HABITAT DESCRIPTIONS
Upland Conifer Forest (ucf)
This habitat includes both spontaneously-occurring upland forests and plantations with
greater than 75 percent cover of conifer trees. Several eastern red cedar forests in the
northwestern part of the site would fit this definition but were not included in the upland
conifer forest habitat. Instead, due to their unique geology and ecological potential, they were
included within the “marble knoll” habitat complex described below.
Natural upland conifer forests on this property were composed of moderately dense eastern
hemlock typically in the range of 20-30 cm (8-12 in) dbh. The shrub and ground layer in
these heavily shaded stands was notably sparse and low in overall diversity. The conifer
plantation was characterized by linear, evenly spaced rows of pure spruce (Picea) with an
approximate dbh of 20 cm (8 in). No shrubs or herbs were observed in the understory, but
several mushroom species were growing on the thick needle mat.
Occurrence at the Study Site
Upland deciduous forest was by far the most extensive unmanaged habitat on the study site,
accounting for approximately 32 percent of the total land area. The largest block of
deciduous forest, more than 105.6 ha (261 ac), occurred in the hilly terrain in the eastern
portion of the property.
In general, forested areas below about 183 m (600 ft) elevation were more disturbed and of
lower habitat quality, especially along the northwest toe (bottom slope) of the eastern hill.
Above this elevation the slope rises steeply to several knoll-like summits. The deciduous
forest that occurred on these steep slopes and summits was relatively mature and of higher
habitat quality. Other high quality oak-maple forest were on the northern and western slopes
of the knoll just northeast of the reservoir, the long strip of forest south of the reservoir
access road, and the deep ravine west of the reservoir. The one upland deciduous forest in the
western section of the property that merits special attention was a narrow belt of mature (3045 cm [12–18 in] dbh) tulip trees located along the edge of the Great Swamp, just south of
the constructed golf course pond.
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RESULTS: HABITAT DESCRIPTIONS
Mixed and conifer forests occupied a small fraction of the upland forest habitat at the site.
We mapped less than 13.7 ha (34 ac) of upland mixed forest, with most of this area occurring
in the hilly region in the eastern half of the property. High quality mixed forests were found a
short distance east (upslope) of the HVPC campus. Embedded within one of these mixed
hemlock-hardwood stands was the site’s only natural upland conifer forest. The 4.2 ha (10.6
ac) conifer plantation was east of Hutchinson Avenue in the northeastern portion of the site.
Conservation Considerations
Forests of all types provide important shelter, foraging, and breeding habitat for numerous
wildlife species. Extensive forested areas that are unfragmented by roads, utility corridors, or
developed lots are especially important for certain species that require large blocks of
continuous habitat for their survival. Such unfragmented forests are becoming increasingly
rare in the region as new roads, and residential and commercial development divide extensive
forests into increasingly smaller and more isolated stands.
Deciduous forests and conifer forests provide important nesting habitat for many species of
raptors and songbirds of conservation concern, and conifer forests can be of special
importance for winter roosting habitat. Forests of all kinds can support a diverse mammal
community, including bobcat (Felis rufus), black bear (Ursus americanus), fisher (Martes
pennanti), porcupine (Erithizon dorsatum), southern flying squirrel (Glaucomys volans), and
many small mammal species. We found woodland jumping mouse (Napaeozapus insignis,
regionally rare) in previously disturbed deciduous forest on the eastern slope of the knoll east
of the reservoir. Forests also provide essential foraging and overwintering habitat for
numerous reptile and amphibian species of conservation concern. Klemens (2005) and Miller
(2005) discuss the known and potential reptile, amphibian, and bird species of the forest
habitats on the “Dover Knolls” site.
Fragmentation of forests can have many negative ecological effects, including the reduction
in size of animal territories, the intrusion of invasive plants and human-adapted predators, the
disruption of migration routes of reptiles, amphibians, and large mammals, and an increase in
road mortality for many wildlife species in their ordinary daily and seasonal movements.
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RESULTS: HABITAT DESCRIPTIONS
The loss of extensive forests has been implicated in the declines of numerous species of
migratory songbirds (Robbins 1980, Ambuel and Temple 1983, Wilcove 1985, Hill and
Hagan 1991), raptors (Bednarz and Dinsmore 1982, Billings 1990, Crocoll 1994), and large
mammals (Godin 1977, Merritt 1987). Many birds and mammals of conservation concern
are dependent upon large tracts of upland forest, including many songbird and raptor species,
bobcat, and fisher, to name just a few.
MARBLE KNOLL (mk)
Ecological Attributes
Marble knolls are an uncommon habitat type that is restricted in Dutchess County to the
Harlem Valley region. They occur primarily along the broad valley floor where folding and
uplifting of the Stockbridge Marble bedrock has created numerous knoll-like hills with
extensive outcrops of bright white to light gray marble bedrock. In the county soil survey
(Faber 2002), marble knoll soils are typically mapped as Farmington-Galway or FarmingtonRock outcrop complex soils. Farmington soils are highly calcareous, extremely shallow (2550 cm [10-20 in] above bedrock), and well drained to somewhat excessively drained. Galway
soils are also calcareous, deeper, and well drained or moderately well drained.
In certain locations in the Harlem Valley, the Stockbridge Marble formation contains layers
of a more crystalline material that is exceptionally soft. As these layers weather, they leave
behind natural sand pits filled with fine calcareous sand and small marble fragments. This
sand is particularly prevalent in the Town of Dover so it is frequently referred to as the
“white sands of Dover.” The sand pits are a unique and ecologically significant feature of the
marble knoll habitat.
At the “Dover Knolls” site, marble knolls reached a maximum elevation of 165m (540 ft).
Several distinct vegetation cover types occurred on the marble knolls, varying according to
the disturbance history. Gently sloping areas were likely grazed or mowed for hay in the
recent past and have since reverted to a calcareous grassland or red cedar woodland. Less
accessible (and thus less disturbed) areas such as steep slopes and ledges supported dense
forests of eastern red cedar.
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RESULTS: HABITAT DESCRIPTIONS
Although the marble knolls were quite variable in vegetation cover type, several plant species
were common throughout the habitat. Eastern red cedar was one of the most frequently
encountered, but individuals were generally small (5-10 cm [2–4 in] dbh) and comprised only
30 to 60 percent cover in the open cedar woodland areas. Between the clumps of cedar were
networks of small grassy openings and sparsely vegetated sand pits. Characteristic species in
these openings included little bluestem (Schizachyrium scoparium), sweet vernal grass
(Anthoxanthum odoratum), poverty grass (Danthonia spicata), Muhlenberg’s sedge (Carex
muhlenbergii), eastern woodland sedge (C. blanda), ebony spleenwort (Asplenium
platyneuron), gray goldenrod (Solidago nemoralis), rough-stemmed goldenrod (S. rugosa),
late purple aster (Aster patens), clammy ground cherry (Physalis heterophylla var. ambigua),
wild marjoram (Origanum vulgare), selfheal (Prunella vulgaris), spotted knapweed
(Centaurea maculosa), white sweet clover (Melilotus alba), hoary vervain (Verbena stricta),
dwarf cinquefoil (Potentilla canadensis), field pussytoes (Antennaria neglecta), and whitlow
grasses (Draba reptans and D. verna). Several native shrub species were also present on the
marble knolls including gray dogwood and, in a few locations, shrubby cinquefoil (Potentilla
fruticosa).
One of the marble knolls had a greater cover of exotic species including common buckthorn,
Bell’s honeysuckle, and autumn olive (Elaeagnus umbellata), perhaps due to more recent or
more intensive disturbance in this area.
Occurrence at the Study Site
We mapped a total of 11 marble knolls at the “Dover Knolls” site. Nine of these formed a
distinct complex totaling nearly 11.7 ha (29 ac) in the northwestern corner of the study area,
in the area west of the sewage treatment plant and north of the golf course. The remaining
two marble knolls were located in the southwestern portion of the site, south of Wheeler
Road. Each of these 11 knolls is numbered on the large format habitat map. In addition, we
identified 6 other marble knolls that have been so disturbed by human activities that they no
longer support the biological community described above. All of these are within or adjacent
to the golf course. These are marked by a star symbol on the large format habitat map, but are
not coded as marble knoll habitat. We also identified a disturbed calcareous sand exposure in
an agricultural field west of marble knoll # 11. This sand exposure is marked with a special
triangle symbol on the large format habitat map.
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RESULTS: HABITAT DESCRIPTIONS
Conservation Considerations
The marble knoll is one of the most important habitats for rare species in the Harlem Valley.
The unusual environmental conditions help support an array of plant and animal species not
generally found in other habitats. Because of their specialized habitat requirements, many of
these species are quite rare in the region and statewide.
The rare plant diversity of marble knolls in the Harlem Valley region is particularly rich, and
includes at least 19 species listed as Endangered, Threatened, or Rare in New York such as
side-oats gramma grass (Bouteloua curtipendula), Torrey’s mountain mint (Pycnanthemum
torrei) (both NYS Endangered), yellow wildflax (Linum sulcatum), large twayblade (Liparis
lilifolia), green milkweed (Asclepias viridiflora), Carolina whitlow-grass (Draba reptans),
Bicknell’s sedge (Carex bicknelli), and northern blazing star (Liatris scariosa var. novaeangliae) (all NYS Threatened). Yellow wildflax, Carolina whitlow-grass, and Bicknell’s
sedge were all found on various marble knolls at this site during the 2004 surveys (see rare
plant discussion below). These imperiled plants occur almost exclusively on marble knolls so
any habitat disturbance could have significant consequences for their long term survival.
The marble knoll also provides habitat for several rare animal species. Several species of
turtles and snakes use the loose, exposed, sandy soils of marble knolls for nesting and
burrowing. Klemens (2005) and Miller (2005) discuss the known and potential reptile,
amphibian, and bird species of the marble knolls. Because the snakes and turtles may travel
considerable distances from their primary wetland or forest habitats to reach the nesting
grounds, the intervening habitats are also of conservation concern. The potential also exists
for various rare tiger beetles (Cicindela) and land snails to inhabit the marble knoll sand pits.
The highest quality knoll (knoll # 9) was the second largest (8.5 ac) on the site with more
than 2 ac of diverse calcareous meadow/open red cedar woodland, prolific marble pavement
and ledge outcrops, an apparently healthy population of yellow wild flax (NYS Threatened),
and a high potential for additional rare plant species. Although knoll # 1 supported healthy
populations of at least two different state listed plants and was the largest marble knoll on
this site, its overall quality was diminished slightly by a high abundance of non-native plant
species and a low open meadow cover. However, knoll # 1 may be a suitable candidate for
restoration efforts (e.g. non-native species removal, selected clearing) that could increase its
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overall habitat quality. Other high quality marble knolls (knoll #s 2, 6, 8, & 11) were
somewhat smaller and contained fewer and smaller meadow openings or bare sand
exposures.
The spatial relationship of the site’s marble knolls to each other and to other habitats types
should be considered when assessing overall habitat quality and biodiversity potential. For
example, the close proximity of knolls # 2 through 9 to each other may facilitate plant and
animal dispersal between the individual knolls, thereby increasing the importance of each
knoll to the maintenance of local biodiversity. Such dispersal is particularly important for
yellow wild flax and Carolina whitlow grass (NYS Threatened), two annuals that must
continually reestablish themselves throughout the habitat by seed dispersal. Even medium
quality marble knolls such as # 3, 4, and 5 may be important to plant and animal dispersal. If
these knoll habitats were lost, knoll # 2 (a high quality habitat) would become isolated.
Knolls # 7 and 8 were adjacent to and upgradient of good quality fen habitat. Development of
these knolls would likely affect the fen adversely by affecting groundwater and surface water
quality and quantity.
Because of the rarity of marble knolls and their importance to regional biodiversity, we
recommend that special measures be taken to protect their ecological integrity. These
measures include preventing the direct loss or degradation of the habitat, preventing soil
erosion, and maintaining unfragmented connections with other marble knolls and with nearby
wetlands, forests, and other habitats essential to the plants and animals of marble knolls.
RED CEDAR WOODLAND (rcw)
Ecological Attributes
The red cedar woodland is a former oldfield habitat where eastern red cedar is now
prominent in the overstory, but typically represents less than 50 percent total cover. On the
study site, openings among the cedar supported various upland meadow and shrubby oldfield
species including a variety of upland grasses, Canada goldenrod (Solidago canadensis),
rough-stemmed goldenrod, spotted knapweed, white sweet clover, Queen Anne’s lace
(Daucus carota), gray dogwood, and young cottonwood. Red cedar woodlands on recently
abandoned pastures or hayfields tended to have a greater cover of open meadow with young,
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widely spaced cedar, while those on longer abandoned fields had denser stands of older
cedar.
The marble knolls in the northwest corner of the site had several patches of red cedar
woodland. Because they are an integral part of the “marble knoll” habitat complex, we did
not map these woodlands explicitly.
Occurrence at the Study Site
The six red cedar woodlands on the property (excluding those on the marble knolls) were
quite small, ranging from 0.08 ha (0.2 ac) to slightly more than 0.4 ha (1 ac). Most occurred
within a larger complex of actively mowed upland meadow, shrubby oldfield, and young
upland mixed forest in the western half of the site.
Most of the red cedar woodlands appeared to be of moderately good quality. Two woodlands
of particular note were located close to Pleasant Ridge Road, immediately abutting an old
gravel road. This area appears to have once been part of the larger marble knoll complex, but
previous gravel mining and grading have removed much of the knoll topography. Despite
this disturbance, these patches of red cedar woodland have retained a distinct calcareous
character. Several individuals of shrubby cinquefoil, an extreme calcicole (calcium
associated plant) were observed here, suggesting the potential for some of the rare calcicoles
of the marble knoll habitat.
Conservation Considerations
Red cedar woodlands may provide important habitat for roosting raptors, owls, and many
smaller birds. Red cedar fruit is a food source for several species of birds, and many
songbirds use red cedar for nesting and roosting. Miller (2005) discusses known and potential
bird species associated with red cedar woodlands on the “Dover Knolls” site. The olive
hairstreak (Callophrys gryneus), a regionally rare butterfly, uses red cedar as its primary
larval host.
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SHRUBBY OLDFIELD (sof)
Ecological Attributes
Shrubby oldfield is a term for many kinds of shrub-dominated upland habitats. In most cases,
these lands are transitional between upland meadow and young forest habitat. Most of the
shrubby oldfields in the study area occurred on former agricultural land. The vegetation of
these habitats was highly variable in species composition, height, and density depending on
the disturbance history, soil conditions, and other factors.
The more disturbed shrubby oldfields contained dense thickets of mostly non-native shrubs
such as autumn olive, young black locust, Bell’s honeysuckle, and multiflora rose (Rosa
multiflora). Many of these disturbed areas also had abundant mile-a-minute weed
(Polygonum perfoliatum), an aggressive exotic plant. This thorny, herbaceous vine created an
almost impenetrable thicket in several locations where it had ‘draped’ itself over large areas
of the ground surface and shrub canopy. In areas where mile-a-minute was not extensive,
other species such as Canada goldenrod, rough-stemmed goldenrod, late goldenrod (Solidago
gigantea), lance-leaved goldenrod (Euthamia graminifolia), starved aster (Aster lateriflorus),
New England aster (A. novae-angliae), horse nettle (Solanum carolinense), red clover
(Trifolium pratense), wild madder (Galium mollugo), and Queen Anne’s lace were common.
Less disturbed shrubby oldfields had a relatively lower cover of non-native shrubs and herbs.
Co-dominant shrubs in these areas included gray dogwood, silky dogwood (Cornus
amomum), young black cherry, white ash, and eastern red cedar.
Occurrence at the Study Site
Thirty-three distinct occurrences of shrubby oldfield were mapped on the study site with a
total area of more than 23.8 ha (59 ac). Nearly 71 percent of this area was in seven large
tracts on the eastern half of the site, along the northwestern toe of the eastern hills and in the
plateau region just west of the reservoir. The shrubby oldfields in the western half of the site
were more numerous, but much smaller and were typically composed of narrow linear bands
or patches along the edge of other habitats.
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Although most of the shrubby oldfields on this site should be considered potentially
important habitat, one is singled out here due to its size, comparatively lower exotic shrub
cover, and position within a landscape of very high quality upland deciduous forest. This 2.4
ha (6 ac) occurrence was located in the southeastern end of the site, just south of the reservoir
access road.
Conservation Considerations
Many bird species of conservation concern nest in shrubby oldfields and adjacent upland
meadow habitats. Several raptor species use shrubby oldfields and adjacent meadows for
hunting. Miller (2005) discusses the known and potential bird species associated with the
shrubby oldfield habitat at the “Dover Knolls” site.
Rare butterflies such as Aphrodite fritillary (Speyeria aphrodite), dusted skipper
(Atrytonopsis hianna), Leonard’s skipper (Hesperia leonardus), and, at higher elevations,
cobweb skipper (H. metea) may occur where their host plants are present. Shrubby oldfields
and other non-forested upland habitats may be used for nesting by several turtle species. A
few species of rare plants are known from calcareous oldfields in the region, such as stiff-leaf
goldenrod (Oligoneuron rigidum var. rigidum) and shrubby St. Johnswort (Hypericum
prolificum), both NYS Threatened.
UPLAND MEADOW (um)
Ecological Attributes
This broad category of habitat includes hayfields, pastures, and abandoned fields dominated
by grasses and forbs, as well as active cropland (e.g. cornfield) that is tilled and harvested
regularly. We include cropland with upland meadow not so much for its current habitat
value, but for its potential habitat value. If left uncultivated, cropland areas tend to quickly
revert to upland meadow environments with a much higher habitat value.
Most of the upland meadow on the study site was active cropland with corn as the principal
species. The vegetation of other upland meadows varied considerably; some were dominated
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almost exclusively by tall grasses while others had a mix of grasses and forbs such as Canada
and rough-stemmed goldenrods, white-panicle aster (Aster lanceolatus), New England aster,
heath aster (Aster pilosus), Queen Anne’s lace, brown knapweed (Centaurea jacea),
fleabanes (Erigeron) and Canada horseweed (Conyza canadensis). Several upland meadows
on highly calcareous substrates had abundant little bluestem and unusual calcicoles such as
shrubby cinquefoil.
Occurrence at the Study Site
We mapped more than 45.7 ha (113 ac) of upland meadow habitat on the study site, with
most of it occurring in the active agricultural areas in the far western end. Several mid-sized
meadows occurred along the northeast edge of the golf course and in the abandoned
recreational area east of the walking track on the former HVPC campus.
A large (2.8 ha [7 ac]) expanse of comparatively high quality, grass-dominated hayfield
mentioned above was located in the extreme northwestern corner of the property, mid-way
between Pleasant Ridge Road and Wheeler Road. The calcareous upland meadows
mentioned above for their potential habitat value were in several locations: one bordered an
old gravel road in the northwestern portion of the site, approximately 104 m (340 ft) from
Pleasant Ridge Road, and one was on a small knoll embedded within a larger upland meadow
in the eastern half of the site, approximately 41 m (135 ft) east of the HVPC walking track.
Conservation Considerations
Upland meadow is a biologically important habitat type that appears to be disappearing at a
faster rate than many other habitats in the region. While some upland meadows have simply
been abandoned and have reverted to forest, many others have been converted to residential
or commercial uses.
Although there can be significant habitat value (e.g. for invertebrates) in small patches of
upland meadow, large patches have especially important habitat value for grassland breeding
birds. These species are highly dependant on extensive meadow habitats for nesting and
foraging. The decline of grassland-breeding birds in the Northeast has been attributed to the
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loss of suitable habitat (Askins 1993, Vickery 1994, Jones and Vickery 1995). Birds nesting
in meadows surrounded by developed land uses are also more vulnerable to a variety of
disturbances, including nest predation by human-adapted predators such as raccoon and
striped skunk. Miller (2005) discusses the known and potential bird species associated with
upland meadows on the “Dover Knolls” site.
Upland meadows with loose soil may be used for nesting by several turtle species of
conservation concern. Several species of rare butterflies, such as Aphrodite fritillary, dusted
skipper, Leonard’s skipper, and swarthy skipper (Nastra lherminier) use upland meadows
that support their particular host plants.
OAK-HEATH BARREN (ohb)
Ecological Attributes
The oak-heath barren is an uncommon habitat type typically found on ridge tops, summits,
and upper slopes where exposed acidic bedrock covers 70 percent or more of the ground
surface. Small amounts of extremely thin and excessively drained soil are found within
depressions and crest areas. The exposed nature of these habitats makes them particularly
susceptible to wind, ice and, at least historically, fire disturbance. Such droughty, infertile
and disturbance prone conditions create an especially harsh environment for plants.
On the “Dover Knolls” site, oak-heath barrens were characterized by a relatively sparse and
stunted plant community. Trees, for example, covered no more than 25 percent of the area
and had an average height around 4.6 m (15 ft). Common tree species included chestnut oak,
black oak, red maple (Acer rubrum), and eastern red cedar, typically in the range of 10-15 cm
(4-6 in) dbh. The tall shrub layer was notably patchy with highbush blueberry, young black
birch, striped maple, black cherry, and hop-hornbeam (Ostrya virginiana). Lowbush
blueberry (Vaccinium pallidum) was the main species in the lower shrub layer, often forming
small thickets in unshaded areas with slightly deeper soil. Clubmosses (Lycopodium), true
mosses, and rock tripe (Umbilicaria) formed thick carpets on the bedrock surface. Other less
abundant species included poverty grass, common hairgrass (Deschampsia flexuosa),
Pennsylvania sedge (Carex pensylvanica), white-tinge sedge (C. albicans var. albicans),
blue-ridge sedge (C. lucorum), white snakeroot (Eupatorium rugosum) and downy goldenrod
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(Solidago puberula). Ferns such as rock polypody (Polypodium vulgare) and ebony
spleenwort grew in crevices along the rock face.
Occurrence at the Study Site
A single small patch of oak-heath barren was mapped in the isolated, triangular parcel in the
far eastern end of the study area. A few other patches of oak-heath barren, near the 280m
(914 ft) elevation summit northwest of the reservoir were too small to map for this study.
Conservation Considerations
Although oak-heath barrens often appear quite inhospitable, they support a number of very
rare species that are adapted to the dry, exposed conditions or require specialized habitat
features typically associated with rocky outcrops.
Various rare plants of crest, ledge, and talus habitats could potentially inhabit the oak-heath
barren, such as reflexed sedge (Carex retroflexa) (NYS Endangered), clustered sedge (C.
cumulata), mountain spleenwort (Asplenium montanum) (both NYS Threatened), and dittany
(Cunila origanoides) (regionally rare). Several rare butterflies that have either oak or little
bluestem as their primary food-plant tend to concentrate in these habitats, including
Edward’s hairstreak (Satyrium edwardsii), northern hairstreak (Fixsenia favonius), and
dusted skipper. Other butterflies of oak-heath barrens and similar habitats are frosted elfin,
Henry’s elfin, hoary elfin, silvery blue, Horace’s duskywing, and grizzled skipper.
Perhaps the most notable feature of the oak-heath barren is its potential habitat value for
several snake species of conservation concern. Rock fissures provide winter den habitat for
these species, exposed ledges provide basking and breeding habitat, and the surrounding
forests provide foraging grounds. Protection of core denning/breeding habitats is essential for
the long-term survival of these animals. Klemens (2005) discusses the known and potential
reptile species associated with oak-heath barrens on and near the study site.
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CREST, LEDGE, AND, TALUS (clt)
Ecological Attributes
Crests and ledges are areas of exposed bedrock, often occurring on hillsides and ridge tops
but also occurring at low elevations. Exposed (unforested) crests and ledges are rocky, warm,
dry habitats with shallow soil. Talus refers to the rock fragments and boulders that often
accumulate at the base of steep ledges and cliffs.
The oak-heath barren described above is a special type of crest or ledge habitat. Because of
its distinctive plant community and unique habitat value, the oak-heath barren is mapped
separately from the more general crest, ledge, and talus habitats described here.
The mapped crest, ledge, and talus habitats on the study site occurred in areas with acidic
schist bedrock of the Manhattan Formation. Most of this habitat was composed of mid-sized
talus with a small number of bedrock exposures and vertical ledges scattered throughout. The
soils in this rock-dominated terrain were very shallow and appeared to be well drained to
excessively drained. Crest, ledge, and talus habitat on calcareous bedrock was mapped as a
separate overlay.
The plant species that occurred at any particular location of crest, ledge, and talus were
determined by many factors, including the outcrop size, rock type, aspect, exposure, slope,
elevation, and disturbance history. Nearly all of the crest, ledge, and talus areas on the study
site occurred in the high quality, oak-maple dominated upland deciduous forest habitat (see
description above). Ferns such as marginal shield fern, rock polypody, ebony spleenwort and
toothed wood fern (Dryopteris carthusiana) grew along crevices in the rock at several
locations.
Occurrence at the Study Site
Crest, ledge, and talus on acidic bedrock is found in a few areas in the hilly eastern portion of
the study site. The largest examples were on the exceptionally steep slope and summit areas
northwest of the reservoir and in the triangular parcel in the far eastern end of the study area.
Smaller bands of outcrop and ledge occurred on knolls south and northeast of the reservoir.
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Conservation Considerations
Crest, ledge, and talus provide key habitat for a number of vulnerable plants and animals.
Potential rare plants of these habitats include reflexed sedge (NYS Endangered), mountain
spleenwort, clustered sedge (both NYS Threatened), and slender knotweed (Polygonum
tenue) (NYS Rare). The rare northern hairstreak (butterfly, NYNHP S1S3) occurs on crest,
ledge, and talus with oak species, its larval hosts. A number of reptiles, amphibians, and birds
of conservation concern use crest, ledge, and talus for foraging, shelter, and breeding.
Klemens (2005) and Miller (2005) discuss known and potential reptiles, amphibians, and
birds associated with these habitats on the “Dover Knolls” site. Bobcat and fisher are two
declining species that use high-elevation crests and ledges for travel, hunting, and cover.
Bobcat also uses talus habitats for denning.
Crest, ledge, and talus habitats often occur in locations that are valued by humans for scenic
vistas and house sites. Construction of roads and houses destroys crest, ledge, and talus
habitats directly, and causes fragmentation of these habitats and the forested areas of which
they are a part. Rare plants of crests are vulnerable to trampling and collecting and rare
breeding birds of these habitats can be easily disturbed by human activities nearby. Rare
snakes are vulnerable to killing or collecting, to the loss of denning and breeding habitats,
and to disruption of their foraging areas and movement corridors. The shallow soils of these
habitats are especially susceptible to erosion from construction and logging activities, and
from foot and ATV trails. To protect fragile crest, ledge, and talus habitats and the sensitive
species associated with them, activities in the vicinity should be designed to minimize
fragmentation, soil erosion, and direct and indirect disturbance to wildlife.
CALCAREOUS CREST, LEDGE, AND TALUS (cclt)
Ecological Attributes
Calcareous crest, ledge, and talus is similar to the previous habitat type except that the
bedrock is calcareous. On the “Dover Knolls” site, folds and uplifts of the Stockbridge
Marble formation created a landscape of gently rolling hills and steeper knolls and ledges in
the western half of the site. Areas mapped as calcareous crest, ledge, and talus consisted
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mostly of small bedrock outcrops, exposed bedrock pavement, and ledge. Very little
calcareous talus was observed at this site. The soils surrounding these outcrops were highly
calcareous and tended to be very shallow and well drained to excessively drained.
The calcium rich nature of the marble bedrock has a strong influence on the plant community
of these areas. Most of the calcareous crest, ledge, and talus was associated with the marble
knoll habitat described above. Other occurrences were associated with various habitats such
as shrubby oldfield, upland mixed forest, upland deciduous forest, and upland meadow.
Ebony spleenwort tended to be particularly abundant on and near these bedrock outcrops.
Occurrence at the Study Site
The greatest extent of calcareous crest, ledge, and talus on this site was associated with the
marble knoll habitats in the northwestern portion of the site. This rocky terrain extends across
a complex of several pronounced knolls and smaller undulating hills. Several small
occurrences were mapped south of Wheeler Road.
Conservation Considerations
The highly alkaline conditions of calcareous crest, ledge, and talus habitats support a
collection of habitat-specialized and increasingly rare species. Ferns such as smooth
cliffbrake (Pellaea glabella) (NYS Threatened) and walking fern (Camptosorus
rhizophyllus) (regionally rare) are associated with crevices in the rock face, while other rare
plants such as northern blazing-star, small-flowered crowfoot and Carolina whitlow-grass (all
NYS Threatened) may occur in the immediate vicinity of the rock outcrops. The larger
fissures, cavities and exposed ledges may provide shelter, den, and basking habitat for
several snake species of conservation concern. These habitats may also support a diverse land
snail community.
Calcareous crest, ledge, and talus habitats often occur in the valley regions of the Harlem
Valley landscape, typically associated with the fertile farmland. These areas are under
particularly strong development pressure and many of these habitats have been altered.
Construction of roads and houses may destroy calcareous crest, ledge, and talus habitats
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directly, and cause fragmentation of these habitats and the matrix of contiguous habitats of
which they are a part. The shallow soils of these habitats are especially susceptible to erosion
from construction activities. To protect fragile calcareous crest, ledge, and talus habitats and
the sensitive species associated with them, activities in the vicinity should be designed to
minimize fragmentation, soil erosion, and direct and indirect disturbance to wildlife, and to
maintain habitat connections between crest occurrences.
WASTE GROUND (wg)
Waste ground is our term for land that has been severely altered from previous or current
human activity, but lacks pavement or structures. We have applied this term to several areas
of the study site, including an expanse of old coal slag near the abandoned railroad bed and a
few areas of small-scale gravel mining in the site’s northwestern quadrant. Areas that have
been mined recently or have been subsequently disturbed by heavy all-terrain vehicle (ATV)
use remain nearly unvegetated. Other mined areas with less recent disturbance have begun to
revert to upland meadow habitat. If such an area had at least 30 percent vegetation cover
(typically composed of little bluestem and goldenrod) it was classified as upland meadow for
this study.
Although waste ground often has low habitat value, there are notable exceptions. Several
snake and turtle species of conservation concern may use the open, gravelly areas in former
gravel mines for burrowing, foraging, and nesting habitat (see Klemens 2005). Carolina
whitlow-grass (NYS Threatened) could expand into calcareous sand pits in the gravel mines
while other plants such as yellow wild flax and Bicknell’s sedge (both NYS Threatened)
could colonize these areas in the future as they developed into a young red cedar woodland
habitat. The biodiversity value of waste ground can be expected to increase over time as it
reverts to a higher quality habitat.
CULTURAL (c)
We define cultural habitats as areas that are significantly altered and intensively managed,
but are not otherwise developed with pavement or structures. Cultural areas at the study site
included the golf course in the western half of the study area and the larger lawns and
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recreational facilities surrounding the abandoned buildings on the eastern half of the
property. Even though the current ecological value of these areas is reduced by frequent
mowing, application of pesticides and fertilizers, and other types of management, they hold
potential habitat value if abandoned. Many cultural areas are valuable for open space and
provide ecological services such as buffering areas of natural habitat from developed areas
and linking patches of undeveloped habitat together. Because they are already significantly
altered, however, it may be preferable to site new development in these areas instead of in
relatively undisturbed habitats.
HARDWOOD & SHRUB SWAMP (sw)
Ecological Attributes
Hardwood and shrub swamp habitats on the study site varied considerably in their physical
and biological characteristics. These wetland communities were dominated by either
hardwood trees or, less commonly, dense shrubs. Nearly all of the swamps observed on this
site appeared to be at least moderately calcareous.
Hardwood and shrub swamps within the immediate floodplain of Swamp River are underlain
by Carlisle muck, an organic soil greater than 130 cm (51 in) deep (Faber 2002). These
swamps are flooded regularly, with water levels as high as 1 m (3 ft) or more during the fall,
winter and spring. This inundation appeared to influence the shrub cover, which decreased to
a low of 10 percent in areas directly adjacent to the river channel. Areas farther from the
active floodplain had a much shallower water regime with most water levels less than 15 cm
(6 in) deep during 2004. The shrub and young tree layer was denser in these locations,
reaching a maximum of 75 percent cover. Swamps found elsewhere on the property were
underlain by mineral soils formed from alluvium deposits or glacial till. These include Sun
silt loam, Wayland silt loam, and Raynham silt loam (Faber 2002).
The dominant tree species found in most areas of forested swamp included red maple, silver
maple (Acer saccharinum), green ash, black ash (Fraxinus nigra), American elm (Ulmus
americana), slippery elm (U. rubra), and eastern cottonwood (Populus deltoides). Spicebush
(Lindera benzoin) was by far the most abundant shrub in forested swamps. Other shrubs
included silky dogwood, gray dogwood, poison sumac (Toxicodendron vernix), arrowwood
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(Viburnum dentatum var. lucidum), nannyberry (V. lentago), winterberry (Ilex verticillata),
speckled alder (Alnus incana), black willow (Salix nigra) and, in the wettest areas,
buttonbush (Cephalanthus occidentalis). An unusual depressional shrub swamp in the far
southwestern corner of the site appeared more acidic and was dominated by highbush
blueberry, and swamp azalea (Rhododendron viscosum).
Common plants in the groundlayer in most areas included skunk cabbage (Symplocarpus
foetidus), spreading goldenrod (Solidago patula), false nettle (Boehmeria cylindrica),
jewelweed (Impatiens capensis), marsh fern (Thelypteris palustris), cinnamon fern
(Osmunda cinnamomea), royal fern (O. regalis), sensitive fern (Onoclea sensibilis), tussock
sedge (Carex stricta), lake sedge (C. lacustris), hop sedge (Carex lupulina), and longhair
sedge (C. comosa). Hardwood swamp areas with deeper, more permanent water tended to
have a number of additional species typically associated with emergent marsh habitat.
Occurrence at the Study Site
Hardwood and shrub swamp was the second most extensive habitat type on the study site,
encompassing an area of more than 60 ha (148 ac). These swamps ranged in size from less
than 0.4 ha to 13 ha (< 1 to 33 ac) and were often contiguous with other wetland habitats
such as emergent marsh and wet meadow.
Nearly 53 percent of the total swamp area was located on the broad floodplain of Swamp
River. This is part of the Great Swamp, the largest wetland complex in southeastern New
York. Although the swamp has a long history of human disturbance on this site, the swamp
interior in many locations was still of high quality.
Most of the remaining occurrences of hardwood and shrub swamp were embedded within
larger wetland complexes that are (or historically were) contiguous with the Great Swamp.
These swamps varied in habitat quality according to their disturbance history. A second
concentration of high quality hardwood and shrub swamp occurred immediately to the
northeast of the reservoir, and a number of smaller swamps were found along various
drainageways throughout the study site.
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Conservation Considerations
Hardwood and shrub swamps are important habitat for a wide variety of species, especially
when the swamp is contiguous with other wetland types or embedded within large areas of
upland forest. Calcareous swamps such as those of the Harlem Valley tend to support a
particularly diverse plant and animal community, including several species of conservation
concern.
Imperiled plants such as dwarf huckleberry (Gaylussacia dumosa), southern dodder (Cuscuta
obtusiflora) (both NYS Endangered), swamp birch (Betula pumila), spotted pondweed
(Potamogeton pulcher), and Long’s bittercress (Cardamine longii) (all NYS Threatened)
have been observed in various locations (offsite) in the Great Swamp. Other rare plants of
forested swamps that could occur here are swamp cottonwood (Populus heterophylla) (NYS
Threatened) and mossycup oak (Quercus macrocarpa ) (regionally rare). We found
mossycup oak along the western edge of the Great Swamp. Rare or declining hawks, owls,
waterfowl, and songbirds are potential nesters in large hardwood swamps. Pools within
swamps are used for foraging and breeding by a variety of reptile and amphibian species of
conservation concern. Klemens (2005) and Miller (2005) discuss the known and potential
reptile, amphibian, and bird species of the hardwood swamp habitats on the “Dover Knolls”
site.
Maintaining the water quality, quantity, and flow patterns is vital to preserving the integrity
of swamps. Nutrient enrichment or stormwater runoff can alter the physical and chemical
conditions and potentially jeopardize the rare, threatened, or endangered species as well as
the common species associated with these habitats.
EMERGENT MARSH (em)
Ecological Attributes
An emergent marsh is a wetland that has standing water for most or all of the growing season
and rooted herbaceous vegetation that emerges above the water surface. On the study site,
emergent marshes occurred at the fringes of deeper water bodies (e.g. lakes, ponds, and
rivers), and within other wetland habitats such as hardwood swamps. Two bands of marsh in
the northern end of the Great Swamp on this site appeared to be historic meanders in the river
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channel that were severed when this portion of Swamp River was dredged and straightened
in the early 1900s.
Water depths in most areas of emergent marsh ranged from 20 to 91 cm (8 to 36 in) during
the wettest part of 2004. The soil beneath these wetlands consisted of either recently
deposited alluvium or highly decomposed organic muck. Tree cover was typically negligible.
The plant community in these marshes often occurred in distinct zones based on water depth.
The deepest areas consisted of either open water or thick mats of submerged and aquatic
species such as southern pond lily (Nuphar advena), smaller forget-me-not (Myosotis laxa),
spiny coontail (Ceratophyllum echinatum), and common water purslane (Ludwigia palustris).
Patches of water-willow (Decodon verticillata) occurred in deeper marshes along Swamp
River in the southern end of the site. Slightly shallower zones contained abundant burreed
(Sparganium americanum), smartweed (Polygonum ?punctatum), pickerelweed (Pontederia
cordata), arrow arum (Peltandra virginica), arrowhead (Sagittaria latifolia) and cardinal
flower (Lobelia cardinalis). Jewelweed, rice cutgrass (Leersia oryzoides), lake sedge (Carex
lacustris), swamp dodder (Cuscuta gronovii), yellow iris (Iris pseudacorus), and mild water
pepper (Polygonum hydropiperoides) were among the many species that occurred in the
shallowest areas. Highly disturbed marshes were dominated by one or more invasive species
such as common reed (Phragmites australis), purple loosestrife (Lythrum salicaria), or reed
canary grass (Phalaris arundinacea).
Occurrence at the Study Site
Twenty-eight distinct emergent marsh habitat units were mapped on this site. Most were very
small (less than 0.2 ha [0.5 ac]) and were associated with the fringes of Swamp River and the
interior regions of the Great Swamp.
The largest emergent marsh on the study site (slightly more than 0.8 ha [2 ac]) was part of a
wetland complex immediately northeast of the reservoir. This marsh may have considerable
habitat value due to its moderate size, physical structure, diverse plant community, and
relative isolation from human activities. Although much smaller, several other marshes along
sluggish secondary streams in the far southern end of the Great Swamp were also potentially
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significant due to the diversity of the plant community and the lower incidence of invasive
species.
Conservation Considerations
High quality emergent marsh is a somewhat uncommon wetland habitat that can often
support a diverse array of common and rare species.
Emergent marshes provide crucial nesting and nursery habitats for a number of marsh birds
and waterfowl, including several NYS Threatened and Special Concern species. Miller
(2005) discusses the known and potential bird species of the marsh habitats on the “Dover
Knolls” site. Marshes are also important habitats for rare reptiles and amphibians, which are
discussed by Klemens (2005). Several rare plant species are known from emergent marshes
in the region, including buttonbush dodder (Cuscuta cephalanthi) (NYS Endangered) and
spiny coontail (NYS Threatened). We found the latter in emergent marsh and other areas
along the Swamp River. Marshes may support a diverse dragonfly and damselfly community
including rare species such as New England bluet (Enallagma laterale) (NYNHP Watch
List).
Marshes are sensitive to various stresses from upgradient sources. Nutrient pollution,
stormwater runoff, and sedimentation can lead to dramatic changes in the plant and animal
communities of marshes, including the invasion of non-native plants such as purple
loosestrife and common reed. Noise and direct disturbance from human activities can
discourage breeding activities of marsh birds. Because many animal species of marshes
depend equally on surrounding upland habitats for their life history needs, protection of the
ecological functions of marshes must include protection of surrounding habitats.
FEN (f)
Ecological Attributes
A fen is an open herbaceous and low shrub wetland fed by calcareous groundwater seepage.
Fens are characterized by a distinctive plant community, low and sometimes sparse
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vegetation, a tussocky ground surface, and shallow rivulets. The surface soil layer is typically
soft and may be organic or mineral in nature. Fens in the Harlem Valley region are
concentrated in areas underlain by Stockbridge Marble, a dolomitic marble bedrock.
Fens on the HVPC site had not been recently grazed or mowed and some contained dense tall
shrub thickets. However, most areas still contained fen openings with diverse herbaceous
plant communities. Common forbs included spreading goldenrod, bog goldenrod (Solidago
uliginosa), grass-of-parnassus (Parnassia glauca), purple stem aster (Aster puniceus), and
purple avens (Geum rivale), among numerous others. Sedges were diverse and often quite
abundant, and included porcupine sedge (Carex hystericina), yellow sedge (C. flava), interior
sedge (C. interior), prickly bog sedge (C. atlantica ssp. atlantica), bristly-stalked sedge (C.
leptalea), limestone meadow sedge (C. granularis), woolly fruit sedge (C. lasiocarpa), lake
sedge, cottongrass (Eriophorum), and twig rush (Cladium mariscoides). Shrubby cinquefoil
was by far the dominant species in the lower shrub layer, while other calcicole shrubs such as
beaked willow (Salix bebbiana), northern gooseberry (Ribes hirtellum), and poison sumac
tended to be more localized. The tall shrub layer was composed of various shrub swamp
species such as alder, pussy willow (Salix discolor), and silky dogwood.
Occurrence at the Study Site
Slightly more than 3.4 hectares (8.4 ac) of fen habitat was mapped in four locations on the
study site. All but one of these fens was a small ‘remnant’ patch within a wetland complex of
disturbed wet meadow or shrub swamp. Two of the small fen patches were near the
northeastern property boundary and one was in the far southwestern corner of the site, south
of Wheeler Road. Despite their small size, these fens may be very important for biodiversity
and should be considered significant habitat areas.
A single 3 ha (7.6 ac) fen occurred at the base of a steep slope in the northwestern corner of
the site, adjacent to Pleasant Ridge Road. Although the portion nearest the road was choked
with invasive plant species, the southern half contained broad expanses of higher quality fen
and even an area of harsher sloping fen. The ecological value of this end of the fen is
expected to be considerable.
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Conservation Considerations
Fens are perhaps one of the most biologically diverse habitats in the Harlem Valley, but they
are also one of the most imperiled due to their overall rarity and their sensitivity to
disturbance. Because of their unusual chemistry, hydrology, and structure, fens provide
habitat for an array of highly specialized species. Many of these species are restricted to fens
and are quite vulnerable to extirpation.
Fens are the core habitat for the bog turtle (Clemmys muhlenbergii) (Federally Threatened,
NYS Endangered) in southeastern New York, providing critical basking, nesting, and
foraging habitat for this species. Adjacent marshes and swamps provide important summer
refuge and winter hibernation habitat, and are considered essential parts of the bog turtle
habitat complex.
Fens are also used by other rare reptiles and several imperiled songbird and hawk species.
Klemens (2005) and Miller (2005) discuss the known and potential reptile, amphibian, and
bird species of the fen habitats on the “Dover Knolls” site. Rare butterflies such as Dion
skipper (Euphyes dion) and black dash (E. conspicua), as well as rare dragonflies such as
forcipate emerald (Somatochlora forcipata) and Kennedy’s emerald (S. kennedyi), are largely
restricted to fen habitats. More than 12 different plants of conservation concern are found
almost exclusively in fen habitats, including bog valerian (Valeriana uliginosa), scarlet
Indian paintbrush (Castilleja coccinea) ovate spikerush (Eleocharis ovata) (all NYS
Endangered), handsome sedge (Carex formosa), Schweinitz’s sedge (C. schweinitzii), swamp
birch (Betula pumila) (all NYS Threatened), and spreading globeflower (Trollius laxus)
(NYS Rare).
Fens are highly vulnerable to degradation from activities in nearby upland areas. Nutrient
pollution from septic systems, fertilizers, or road runoff, disruption of groundwater flow from
wells or excavation, sedimentation from construction activity, or direct physical disturbance
can lead to changes in the character of the habitat, including a significant decline in overall
plant diversity and invasion by non-native species and tall shrubs (Aerts and Berendse 1988,
Panno et al. 1999, Richburg et al. 2001, Drexler and Bedford 2002). Such changes can render
the habitat unsuitable for the animals and plants that require the special structural, chemical,
or hydrological environment of an intact fen.
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WET MEADOW (wm)
Ecological Attributes
A wet meadow is a wetland dominated by herbaceous (non-woody) vegetation and with little
or no standing water for much of the year. Wet meadows on the study site occurred in
association with hardwood and shrub swamp, emergent marsh, and calcareous wet meadow
(a special type of wet meadow described below).
The wet meadows on this site were generally located near intensive human activity (e.g.,
agricultural or recreational use) and therefore tended to be more chronically disturbed than
other wetlands on the site. Many were characterized by dense stands of one or more invasive
species such as reed canary grass, common reed, or purple loosestrife. Less disturbed areas
contained other species such as jewelweed, arrow-leaved tearthumb (Polygonum sagittatum),
spotted joe-pye weed, Canada and late goldenrods, and path rush (Juncus tenuis).
Occurrence at the Study Site
We mapped nearly 7.3 ha (18 ac) of wet meadow habitat in the study area, 70 percent of
which was concentrated in a linear band of wetland in the western end of the property. This
band was composed of different wetland types extending westward and then northward from
the Great Swamp, eventually crossing Wheeler Road. While all of these wet meadows were
rather disturbed, their habitat value should not be overlooked.
Conservation Considerations
Extensive wet meadows or those that are part of larger meadow complexes share much of the
habitat value of upland meadows (see above) for rare invertebrates, raptors, and grassland
breeding birds
Wet meadows are often part of larger complexes of meadows and shrubby oldfield habitats
that are prime sites for development, but they are often omitted from state, federal, and sitespecific wetland maps and are frequently overlooked in the environmental reviews of
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development proposals. Wet meadows on the site should be accurately delineated and
mapped, and they should be regarded as potentially important habitats during the
environmental review process.
CALCAREOUS WET MEADOW (cwm)
Ecological Attributes
A calcareous wet meadow is a wet meadow (see above) that is strongly influenced by
calcareous groundwater or soils. On the “Dover Knolls” site, these wetland communities
were often associated with the margins of calcareous swamps and fens.
Calcareous wet meadows on this site had many plant species common to other wet meadows
but were distinguished by the presence of various calcicoles such as spreading goldenrod,
New York ironweed (Vernonia noveboracensis), bog goldenrod, purple stem aster, fringed
gentian (Gentianopsis crinita), woolly fruit sedge, porcupine sedge, drooping bulrush
(Scirpus pendulus), and shrubs such as red-osier dogwood (Cornus sericea) and poison
sumac.
Occurrence at the Study Site
We documented a total of 11 calcareous wet meadows on this property. All were either
directly adjacent to the Great Swamp, or were embedded within wetland complexes that are
(or historically were) contiguous with the Great Swamp.
The largest calcareous wet meadow (1.1 ha [2.8 ac]) occurred along the edge of the Great
Swamp in the southwestern portion of the property. This occurrence was significant due to its
size, its moderate plant diversity and its position next to a large area of high quality
hardwood swamp. The calcareous wet meadow in the center of the walking track, just east of
Route 22, was surprisingly diverse with a number of sedges not found elsewhere on the
property. The occurrence immediately west of Hutchinson Avenue (just north of the HVPC
campus) may also have high habitat value due to its fen-like features, including small
tussocks and pools. The smallest calcareous wet meadow, located nearly halfway between
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the sewage treatment plant and the golf course, should not be overlooked because it
contained several strong calcicoles including grass-of-parnassus.
Conservation Considerations
Calcareous wet meadows that are part of larger meadow complexes may share many of the
habitat values of large upland meadows (see above). High quality calcareous wet meadows
with diverse native plant communities may support some of the rare plants of fens, such as
NYS Threatened Schweinitz’s sedge (Carex schweinitzii), and a variety of rare butterflies if
their host plants are present.
Several reptile species of conservation concern may use calcareous wet meadows for summer
foraging and even nesting. Klemens (2005) discusses the known and potential reptile species
associated with the calcareous wet meadows on the “Dover Knolls” site.
Calcareous wet meadows share with fens many of the same sensitivities to disturbance. They
are particularly vulnerable to nutrient enrichment and siltation, which often facilitate the
spread of non-native species. In addition, because calcareous wet meadows tend to be on the
dryer end of the wetland continuum, they are often omitted from state, federal, and sitespecific wetland maps and are frequently overlooked in the environmental reviews of
development proposals. Calcareous wet meadows on this site should be accurately delineated
and mapped, and they should be regarded as potentially significant habitats during the
environmental review process.
INTERMITTENT WOODLAND POOL (iwp)
Ecological Attributes
An intermittent woodland pool is a small wetland habitat that has standing water during
winter and spring and typically dries by mid- to late summer. Intermittent woodland pools
are surrounded partially or entirely by upland forest and are a subset of the “vernal pool”
habitat (which may or may not be surrounded by forest). The hydroperiod, or duration of
standing water, varies from year to year depending on precipitation, soils, and other factors.
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Intermittent woodland pools have no permanent inlet or outlet and are generally isolated
from other wetland systems.
Despite the small size of intermittent woodland pools, those that hold water through early
summer can support amphibian diversity equal to or greater than that of much larger
wetlands (Semlitsch and Brodie 1998, Semlitsch 2000). The seasonal drying and isolated
nature of these pools help exclude fish, which are major predators on amphibian eggs and
larvae. The surrounding forest provides essential habitat for adult and juvenile amphibians
during the non-breeding season.
Nearly all intermittent woodland pools on the study site occurred in upland deciduous forest
habitat. While most of the smaller pools appeared heavily shaded during the summer, the
largest ones contained small canopy gaps that allowed sunlight to reach more of the pool
surface. Most of the site’s woodland pools had maximum water depths of 30-35 cm (12–14
in) during our early fall visits in 2004.
Wetland vegetation in the intermittent woodland pools was not as extensive as that in other
wetlands, but several common species were present in most occurrences. Trees such as red
maple, American elm, and green ash grew along the edge and on large consolidated
hummocks (woody root crowns) in the pool. Various shrubs such as winterberry, highbush
blueberry, and silky dogwood were also relatively common on these hummocks. The ground
layer was typically sparse, but species such as tussock sedge, hop sedge, cinnamon fern, and
water horehound (Lycopus) were locally abundant.
Occurrence at the Study Site
We mapped a total of five intermittent woodland pools within the study site. The pools are
numbered 1-5 on the large format habitat map. Pools 1-4 are in the hilly eastern part of the
property; pool 5 is at the edge of a hardwood swamp in the northwestern portion of the site,
approximately 855 feet north of Wheeler Road.
Each of these intermittent woodland pools should be considered ecologically significant. In
particular, pool #1 might be of particularly high habitat quality due to its size, structure, and
isolation from human activities.
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Conservation Considerations
We consider intermittent woodland pools to be one of the most imperiled habitats in the
region. They are frequently overlooked in environmental reviews of proposed developments
and are drained, filled, or dumped in by landowners and developers. Intermittent woodland
pools are often excluded from federal and state wetland protection due to their small size,
their temporary surface water, and their isolation from other wetland habitats. It is these very
characteristics of size, isolation, and intermittency, however, that make woodland pools
uniquely suited to species that do not reproduce or compete successfully in larger wetland or
pond systems.
Intermittent pools provide critical breeding and nursery habitat for an array of rare amphibian
species, especially several species of salamander and frog. Klemens (2005) gives a complete
account of the known and potential amphibian and reptile species associated with intermittent
woodland pools on the “Dover Knolls” site. Several vulnerable duck species may use
intermittent woodland pools for nesting, brood-rearing, and foraging. The invertebrate
communities of these pools can be rich, providing abundant food for a variety of songbirds.
Miller (2005) discusses the known and potential bird species of the intermittent woodland
pool habitat on the “Dover Knolls” site. Springtime physa, a regionally rare snail, is often
associated with intermittent woodland pools. At least two rare plants, featherfoil (Hottonia
inflata) (NYS Threatened) and false hop sedge (Carex lupuliformis) (NYS Rare), occur in
intermittent woodland pools in the lower Hudson Valley.
Important overall conservation measures for intermittent woodland pools include protecting
pools from filling, draining, dumping, dredging, logging, pollution, siltation, or compaction;
protecting large areas of surrounding forests; and preserving overland connections between
pools. Calhoun and Klemens (2002) recommended protecting a 228 m (750 ft) forested
radius around each intermittent woodland pool, an area representing the critical habitat zone
for obligate pool-breeding amphibians.
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RIVER (r)
A single occurrence of river habitat, the Swamp River, was mapped on this site. Nearly all of
the onsite portion of this river channel was dredged and straightened sometime prior to the
1930s. As a result, key habitat features such as meanders and side channels were missing,
although some of these features still occurred along a tiny stretch of the river near the
southern property line. Water flows northward at a particularly sluggish rate, perhaps due to
the widened and deepened channel.
This river supported a number of aquatic plant species, especially in areas where the forest
canopy was more open. Common species included spiny coontail, common coontail
(Ceratophyllum demersum), waterweed (Elodea canadensis), water chickweed (Callitriche
palustris), Illinois pondweed (Potamogeton illinoensis), variable pondweed (P. gramineus),
southern pond lily, and common duckweed.
Although historically disturbed, this portion of Swamp River may provide important habitat
for several rare species. Spiny coontail, a New York State Threatened species, was observed
in the river at several locations during this study. The New York State Threatened longear
sunfish (Lepomis megalotis), has been observed in other portions of Swamp River during
other surveys (Murphy 1998) and could conceivably be found at this site. The river may also
be primary foraging, migration, and winter habitat for turtle species of conservation concern.
Klemens (2005) discusses the known and potential reptile and amphibian species of the river
habitat on the “Dover Knolls” site. Mink (Mustela vison) (a declining species) was observed
in Swamp River during this study.
CONSTRUCTED POND (cp)
Constructed ponds include those water bodies that have been excavated or dammed by
humans, either in existing wetlands or in upland terrain, for such purposes as aesthetics,
recreation, and drinking water.
Only three occurrences of constructed pond habitat were found on the study site. The pond in
the southeastern end of the golf course had small bands of emergent marsh along the edge,
but still retained an unnatural appearance due to the effects of human activities on the
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surrounding lands (e.g. nutrient enrichment, pesticides). Another small constructed pond was
in the northwestern end of the site, along the edge of an agricultural field. The largest
occurrence was the 3.6 ha (9 ac) reservoir in the eastern part of the site. Although a dam
maintains the water level, other aspects of this lake mimic a natural pond including a nearly
continuous border of upland forest and abundant aquatic vegetation such as western
waterweed (Elodea nuttallii) and two-headed water starwort (Callitriche heterophylla).
If constructed ponds are not intensively disturbed by human activities, they can be important
habitats for many of the common and rare species associated with natural open water
habitats. Numerous rare species of submerged aquatic plants can occur in constructed ponds.
Several raptors and marsh birds may use these open water areas for hunting and foraging.
Constructed ponds may also be important breeding and migratory stopover habitat for
various ducks. Several turtle species of conservation concern may use constructed ponds as
vital refuge habitat during droughts and for overwintering and breeding. Klemens (2005) and
Miller (2005) discuss the known and potential reptile, amphibian, and bird species of the
constructed pond habitats on the “Dover Knolls” site.
INTERMITTENT & PERENNIAL STREAM
Perennial streams flow continuously during years with normal precipitation, but some may
dry up during droughts. Intermittent streams flow only during certain times of year or after
rains and snowmelt. They are the headwaters of many perennial streams, and are significant
water sources for lakes, ponds, and wetlands of all kinds. At least 25 streams or segments of
streams were mapped on the study site, most of which were intermittent in nature and located
in the hilly eastern part of the site.
Several species of conservation concern could occur in and near the streams of the study site.
Plants such as goldenseal (Hydrastis canadensis) (NYS Threatened) and winged monkey
flower (Mimulus alatus) (NYS Rare) may occur along the channel margins of small streams
in hardwood forests. Several rare dragonflies such as arrowhead spiketail (Cordulegaster
obliqua), tiger spiketail (Cordulegaster erronea), and gray petaltail (Tachopteryx thoreyi)
inhabit intermittent streams associated with forest seeps, while others such as sable clubtail
(Gomphus rogersi) favor clear perennial streams in upland forest. Both perennial and
intermittent streams provide vital breeding, larval, and adult habitat for amphibians,
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particularly several salamander species. Klemens (2005) discusses the known and potential
reptile and amphibian species of the stream habitats on the “Dover Knoll” site.
The habitat quality of a stream is affected not only by direct disturbance to the stream or its
floodplain, but also by land uses throughout the watershed. Activities in the watershed that
cause soil erosion, increased surface water runoff, reduced groundwater infiltration, or
contamination of surface water or groundwater are likely to affect stream habitats adversely.
Removal of trees or other shade-producing vegetation can lead to elevated stream
temperatures that can adversely affect aquatic invertebrate and fish communities. Effective
protection of stream habitats, therefore, requires attention not only to the stream channel, but
to land uses in the riparian corridor and throughout the stream’s watershed.
SPRINGS & SEEPS
Springs and seeps are places where groundwater discharges to the ground surface, either at a
single point (a spring) or diffusely (a seep). Although springs often discharge into ponds,
streams, or wetlands such as fens, we mapped only springs and seeps that discharged
conspicuously into upland locations. The habitats created at springs and seeps are determined
in part by the hydroperiod and the chemistry of the soils and bedrock through which the
groundwater flows before emerging.
At least eight distinct springs or seeps were observed on the site, with nearly all occurrences
located along the lower slopes or in the upper plateau area of the eastern hills. One unusual
seep, located in a region of calcareous groundwater approximately halfway between the
sewage treatment plant and the golf course, may possess special habitat potential due to its
apparent calcareous chemistry.
Springs and seeps can be important water sources for many organisms during droughts, and
during winter when some of these habitats may remain free of ice. Because groundwater
discharges at a fairly constant temperature, spring and seep habitats tend to be warmer than
surrounding habitats in winter, and cooler than surrounding habitats in summer. This enables
them to support certain organisms that occur rarely or not at all in other habitats in the region.
Springs can be easily disrupted by disturbance to upgradient land or groundwater.
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A few rare invertebrates such as northern spring amphipod (Gammarus pseudolimnaeus) and
Piedmont groundwater amphipod (Stygobromus tenuis tenuis) appear to be restricted to
springs in the region. Springs emanating from calcareous bedrock or calcium-rich surficial
deposits sometimes support an abundant and diverse snail fauna. Gray petaltail and tiger
spiketail are two rare dragonflies of seeps in the region.
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RARE PLANTS
We found seven plant species listed as rare statewide, 9 regionally rare species and 1
regionally scarce species on the “Dover Knolls” site (Table 2.). Each is briefly discussed
below. The statewide rarity ranks are given in parentheses after the plant name. Each
description also includes rare plant location numbers that correspond to the individual rare
plant numbers depicted on the accompanying large format habitat map. An explanation of the
statewide (NYS- or NYNHP-listed) and regional rarity ranks is given in Appendix A.
STATEWIDE RARE SPECIES
Emmons’ sedge (Carex albicans var. emmonsii) (NYNHP S3W)
Rare Plant Location # 1
Emmons’ sedge has been found in the southern half of New York State primarily on rocky,
wooded slopes, but occasionally in other habitats such as open ridge summits and on
hummocks in deciduous swamps (Barbour 1997). On the “Dover Knolls” site, we found a
small stand of Emmons’ sedge at the southeast corner of the golf course on disturbed,
calcareous, sandy soil (location # 1).
Bicknell’s sedge (Carex bicknellii) (NYS Threatened, NYNHP S3W)
Rare Plant Location #s 2 & 3
Bicknell’s sedge occurs on dry slopes and ridges with calcareous, often sandy, soils. We
found two distinct occurrences on marble knolls north of the golf course. The first occurrence
(location # 2) was on marble knoll # 1, where we found two patches of Bicknell’s sedge. One
patch had approximately 30 plants in dry, herbaceous meadow on the east slope of the knoll.
The other patch, with more than 40 plants, was on the west rim of the knoll summit. The
second occurrence (location # 3) was found on marble knoll #2, and had 8-10 plants of
Bicknell’s sedge.
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Bush’s sedge (Carex bushii) (NYNHP S3W)
Rare Plant Location #4
This is a moderately tall sedge of calcareous old fields. We found a few plants growing with
Bicknell’s sedge on marble knoll # 2.
Carolina whitlow-grass (Draba reptans) (NYS Threatened, NYNHP S2)
Rare Plant Location #s 5, 6, 7, 8, 9, & 10
This is a small (3-8 cm [1.2-3.1in] tall) herb of the mustard family (Brassicaceae) blooming
and fruiting in early spring. We found three distinct occurrences on the marble knolls: a)
hundreds of plants on marble knoll # 1, in at least 4 different openings on the east slope and
on the summit (locations # 5, 6, 7, 8); b) one individual on a small marble outcrop east of
the Pleasant Ridge Road fen (location # 9); c) approximately five plants on marble knoll #
11 southeast of the golf course (location # 10).
Spiny coontail (Ceratophyllum echinatum) (NYS Threatened, NYNHP S3W)
Rare Plant Location #s 11, 12, 13, 14 & 15
This is an aquatic herb of the hornwort family (Ceratophyllaceae) and is typically found in
non-eutrophic, somewhat calcareous ponds and sluggish streams. We found this plant only in
the Swamp River and several associated emergent marshes, both north and south of Wheeler
Road, where it was locally common.
Yellow wild flax (Linum sulcatum) (NYS Threatened, NYNHP S2)
Rare Plant Location #s 16, 17, 18, & 19
This is a 25-70 cm (10-27.5 in) tall herb of the flax family (Linaceae), with narrow leaves
and 1.5-3 cm (0.6-1.1 in) wide yellow flowers in late summer. We found three distinct
occurrences on different marble knolls: a) approximately 100 individuals along open
meadow on marble knoll # 6 (location # 19) b) two different patches with a total of more
that 100 individuals on marble knoll # 9 (location #s 16 & 17) c) on a northwest-facing,
cliff-like marble exposure on marble knoll # 8 (location # 18).
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RESULTS: RARE PLANTS
Smartweed dodder (Cuscuta polygonorum) (NYS Endangered, NYNHP S1)
Rare Plant Location #s 20, 21, & 22
This is a parasitic, vine-like herb of the dodder family (Cuscutaceae) found in shallow
emergent marshes and wetland margins of streams and ponds. This plant may have an
affinity for circumneutral or alkaline soils and waters. We found smartweed dodder in three
locations: a) two different patches along the margin of Swamp River south of Wheeler Road,
growing on water willow (Decodon verticillatus) (location #s 20 & 21), b) one patch in
emergent marsh along the edge of Swamp River north of Wheeler Road, growing on
smartweed (Polygonum) (location # 22).
REGIONALLY RARE AND REGIONALLY SCARCE SPECIES
We found the regionally rare silver-fruited sedge (Carex argyrantha) in a barren like
opening in upland deciduous (oak-hickory) forest. This large (50-80 cm [20-31.5 in] tall)
sedge occurs in open barrens and along path edges on rock ridges in southeastern New York.
We found two individuals of mossycup oak (Quercus macrocarpa): a young tree (ca. 17 cm
[7 in] dbh) along the east margin of the road to the sewage plant (along edge of Great
Swamp), and a large (ca. 100 cm [40 in] dbh) tree on the north side of Wheeler Road in a row
of trees bordering the golf course.
Other regionally-rare species included plantain-leaved sedge (Carex plantaginea) and
leatherwood (Dirca palustris) in the ravine west of the reservoir, Fries’s pondweed
(Potomageton friesii) in the Swamp River, winged loosestrife (Lythrum alatum), woolly
sedge (Carex pellita), rich woods sedge (Carex oligocarpa) and big bluestem (Andropogon
gerardii) in the fen adjacent to Pleasant Ridge Road, and Sprengel’s sedge (Carex
sprengelii) in intermittent woodland pool # 4.
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RESULTS: RARE PLANTS
Table 2. Rare plants found at the “Dover Knolls” study site, 2004.
Scientific Name
Common name
Rarity
Rank1
Habitat(s)2
Rare plant
location #
NYS- or NYNHP-listed
rare species
Carex albicans var. emmonsii
Carex bicknellii
Carex bushii
Draba reptans
Ceratophyllum echinatum
Linum sulcatum
Cuscuta polygonorum
Emmons' sedge
Bicknell's sedge
Bush's sedge
Carolina whitlow-grass
spiny coontail
yellow wild flax
smartweed dodder
S3W
T, S3W
S3W
T, S2
T, S3W
T, S2
E, S1
c, cclt
mk
mk
mk, cclt
s, em
mk, cclt
r, em
big bluestem
silver-fruited sedge
plantain-leaf sedge
rich woods sedge
woolly sedge
Sprengel’s sedge
leatherwood
winged loosestrife
Fries's pondweed
mossycup oak
RS
RR
RR
RR
RR
RR
RR
RR
RR
RR
f
clt
r
f
f
iwp
r
f
s
c, sw
1
2, 3
4
5, 6, 7, 8, 9, 10
11, 12, 13, 14, 15
16, 17, 18, 19
20, 21, 22
Regionally rare or scarce species
Andropogon gerardii
Carex argyrantha
Carex plantaginea
Carex oligocarpa
Carex pellita
Carex sprengelii
Dirca palustris
Lythrum alatum
Potomageton friesii
Quercus macrocarpa
1
2
---------------------
NYS ranks: E = Endangered; T = Threatened; R = Rare (see Appendix A).
NYNHP ranks: S1, S2, S3, W (see Appendix A).
Regional ranks: RR = regionally rare; RS = regionally scarce (see Appendix A).
Habitat abbreviations:
c
cultural
cclt
calcareous crest, ledge, and talus
clt
crest, ledge, and talus
cwm
calcareous wet meadow
em
emergent marsh
f
fen
iwp
intermittent woodland pool
mk
marble knoll
r
ravine
s
stream and river
sof
shrubby oldfield
sw
hardwood and shrub swamp
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DISCUSSION
DISCUSSION
Kiviat (1988) identified four zones in the Town of Dover of particular biological sensitivity
due to their ability to support rare plant and animal species--the marble hills, the Swamp
River wetland complex, the fens, and the East Mountain and West Mountain escarpments.
The “Dover Knolls” site contains large areas of those kinds of environments. The areas that
we feel are of greatest conservation concern on the site are the eastern forested hills, fens,
marble knolls, swamp river & wetlands, and intermittent woodland pools and adjacent
forests.
This report describes existing conditions in 2004 and early 2005. The discussion below
includes some general recommendations for protecting biodiversity on the site, but without
reference to any particular feature of the proposed development project.
EASTERN HILLS
The habitats of particular concern in the eastern hills are the extensive forests, the crest,
ledge, and talus habitats, the oak-heath barrens, the intermittent woodland pools, and the
ravine. The forests are part of a much larger forest area that, though fragmented by roads and
development east and south of the study site, still retains over 400 ha (1000 ac) without roads
or developed lots. Large forests provide habitat for wide-ranging species with large spatial
requirements and “forest interior” species sensitive to disturbance from forest edges. Large
forests are an increasingly rare occurrence in Dutchess County, which magnifies the
importance of those that remain.
The acidic crest, ledge, and talus areas, the oak-heath barrens, and surrounding forests may
provide habitat for several reptiles of conservation concern (see Klemens 2005) that are
known to occur in the Town of Dover. Maintaining undisturbed denning, basking, breeding,
and foraging habitats would require protection of large contiguous areas of forests, ledges,
and crests. Those measures would also help to protect the habitats of interior forest birds, rare
invertebrates of the barrens, and rare plants of the crests, ledges, and barrens.
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DISCUSSION
The forests are also part of the critical habitat complex for the mole salamanders and wood
frogs that breed in intermittent woodland pools. Klemens (2005) discusses known and
potential amphibians associated intermittent woodland pools on the “Dover Knolls” site.
Protecting the juvenile and adult habitat for those amphibians requires maintenance of large
areas of undisturbed forest around the pools. We identified four woodland pools on the study
site in the eastern hills. We recommend protecting an undisturbed zone of approximately 230
m (750 ft) radius around the pools for amphibian non-breeding habitat, and protecting broad
undisturbed corridors between pools to permit safe movement by amphibians between pools
(Calhoun and Klemens 2002).
The shaded environment, the rocky stream substrate, and the clear, cold stream water are
important habitat components of the deep ravine west of the reservoir. The ravine habitat is
vulnerable not only to removal of vegetation on the ravine walls, but also to disturbance
elsewhere in the stream’s watershed that would lead to increased surface runoff, increased
erosion and siltation, or increased surface water temperatures. Any land disturbance on the
hillsides north and south of the ravine could potentially affect the integrity of the ravine walls
and the stream habitat.
The fen areas at the northeast edge of the property are supported in part by the habitats of the
hills rising to the south. Fen habitats are especially sensitive to alterations in surface and
groundwater hydrology and water chemistry. Land disturbance that would affect the quantity
or quality of groundwater flows or surface runoff in the vicinity of the fens would have the
potential to degrade or destroy the fen habitats.
To protect the habitats of the eastern hills, we recommend confining new development to the
lowland areas that are part of the former HVPC campus, and avoiding disturbance to areas in
the watersheds of the ravine or the fens, or within a 230 m (750 ft) radius of the intermittent
woodland pools. Maintaining an undisturbed watershed would also serve to safeguard the
reservoir as a future drinking water source. Avoiding construction of new roads in the hill
region and preventing ATV use of existing roads would protect against the hazards of forest
fragmentation such as disruption of wildlife movement patterns, disruption of nesting
territories of interior birds, road mortality of amphibians & reptiles, and further invasion of
non-native plants.
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DISCUSSION
FENS
Of the four fens identified on the site, the large fen adjacent to Pleasant Ridge Road appears
to be the highest quality, a judgment based on the vegetation structure, plant community, and
size. The fen is connected by small culvert under Pleasant Ridge Road to a wetland lobe of
the Great Swamp. This fen appears to be suitable habitat for the bog turtle. Although
Klemens (2005) found none in his 2004 survey, the bog turtle is often very elusive and may
in fact inhabit this fen now or at some time in the future. The fen south of Wheeler Road,
though small, holds some potential for rare fen species due in part to its contiguity with a
large wet meadow and shrub swamp complex. The western-most of the two fens east of Rt.
22 was somewhat overwhelmed by tall wetland shrubs, with the fen plant community
confined to small openings between the shrubs. Nonetheless, this fen could still support rare
species, especially if other suitable fen habitats occur nearby (offsite). The eastern of those
two fens was small, but had typical fen-like structure and was part of a larger wetland
containing other fen habitat areas. We believe that this fen should also be treated as potential
habitat for the rare plants and animals associated with fens.
To protect the potential biodiversity values of the fens, maintain broad buffer zones of
undisturbed vegetation and soils around each fen, and avoid activities in the upgradient areas
that would alter the quantity or quality of groundwater or surface runoff feeding the fens. If
turtles are found or suspected in the large fen on Pleasant Ridge Road, it may be important to
maintain or even enhance the culvert under the road to allow safe passage between the fen
and the habitats of the Great Swamp to the north.
MARBLE KNOLLS
We found 5 state listed plant species on the marble knolls. Klemens (2005) and Miller (2005)
discuss rare reptile, amphibian, and bird species they observed in the marble knoll habitat.
Many more rare species of plants and animals are known from other such knolls in the Town
of Dover and elsewhere in the Harlem Valley. For some of these the knoll habitats would be
part of a larger habitat complex that includes upland forests, meadows, and intermittent
pools. The marble knoll conservation unit should therefore encompass the larger landscape
around the knolls, and should include contiguous habitats of potential importance to knollinhabiting species.
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DISCUSSION
We recommend protection of the knolls themselves, and large undisturbed swaths connecting
the knolls to each other and to nearby forest and meadow habitats. We also recommend
future surveys for additional rare plants, rare reptiles and amphibians, rare land snails, and
rare tiger beetles on the marble knolls.
SWAMP RIVER/GREAT SWAMP
The Great Swamp is the most extensive wetland complex in the Town of Dover, and is one
of the most important wetland complexes in southeastern New York. We found two rare
plants in the Great Swamp, and numerous other rare plants and animals are known from other
(offsite) areas of the swamp. While the stream and wetland habitats are subject to a host of
influences from throughout the upstream and upgradient watershed, these habitats will also
be affected by onsite land uses. All but the eastern most edge of the site is in the watershed of
the Great Swamp and the Swamp River, and the contiguous wetland areas of the Great
Swamp extend to the extreme western and northeastern portions of the study site.
To protect the swamp and the river, particular attention should be paid to preventing siltladen or chemically contaminated water from reaching any of the wetlands or streams on the
site. All earth-moving and other construction activities should be carefully designed, and
carefully timed and executed, with ample erosion and stormwater controls to prevent siltation
or other pollution from reaching the streams or wetlands.
INTERMITTENT WOODLAND POOLS
Four of the 5 intermittent woodland pools identified on the site were surrounded by extensive
upland deciduous forest. All could support woodland pool-breeding amphibians of
conservation concern. The pools could be important not only to these amphibians but to a
host of other wildlife species that may use them regularly or intermittently, such as various
reptiles, amphibians, waterfowl, bear, bobcat, and fisher. The pool ecology will be
maintained only by prevention of direct disturbance or surface water contamination, and by
protecting the surrounding forests including the connecting areas between pools. The small
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DISCUSSION
intermittent woodland pool in the northwestern part of the site may be important habitat for
various reptiles and amphibians that may occur in this region.
The blueberry/azalea swamp in the southwestern corner of the site (but connected by shallow
wetland to the Great Swamp complex) may also serve as important habitat for various plant
and animal species of conservation concern.
To protect the habitat values of the intermittent woodland pools for pool-breeding
amphibians and other wildlife using the pools, we recommend protecting as much as possible
a 230 m (750 ft) forested radius around each pool and other similar wetlands (Calhoun and
Klemens 2002). Protection should include maintaining the forested canopy and the
microhabitats of the undisturbed forest floor.
SUMMARY RECOMMENDATIONS
Our summary recommendations for the “Dover Knolls” site include the following:
1. As much as possible, concentrate new development in areas with existing structures,
roads, and disturbed habitats.
2. Protect from further disturbance the special habitat areas outlined in the discussion
above, and protect habitat connections between those areas and offsite habitats.
3. Carefully design and implement strict erosion, siltation, and stormwater controls on
all areas of new soil disturbance or vegetation removal.
4. Minimize the extent of new impervious surfaces; maximize the onsite surface water
retention and infiltration.
5. Ensure that wet meadow and calcareous wet meadow wetlands are accurately
delineated and mapped, and that all wetland areas contiguous with the Great Swamp
via offsite wetland lobes be considered part of the Great Swamp and receive the same
level of protection (e.g. 100 foot buffer).
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REFERENCES CITED
REFERENCES CITED
Aerts, R. and F. Berendse. 1988. The effect of increased nutrient availability on vegetation
dynamics in wet heathlands. Vegetatio 76:63-69.
Ambuel, G. and S.A. Temple. 1983. Songbird populations in southern Wisconsin forests:
1954 and 1979. Journal of Field Ornithology 53:149-158.
Askins, R.A. 1993. Population trends in grassland, shrubland, and forest birds in Eastern
North America. Current Ornithology 11:1-34.
Barbour, S. 1997. Rare plant survey of the northern Shawangunk Mountains. Report to the
Shawangunk Biodiversity Partnership, Mohonk Preserve, New York State Office of
Parks and Historic Preservation, and the Nature Conservancy.
Bednarz, J.C. and J.J Dinsmore. 1982. Nest sites and habitat of red-shouldered and red-tailed
hawks in Iowa. Wilson Bulletin 94(1):31-45.
Billings, G. 1990. Birds of prey in Connecticut . Rainbow Press, Torrington, CT. 461 p.
Calhoun, A.J.K. and M.W. Klemens. 2002. Best development practices: Conserving poolbreeding amphibians in residential and commercial developments in the northeastern
United States. MCA Technical Paper No. 5, Metropolitan Conservation Alliance,
Wildlife Conservation Society, Bronx, New York. 57p
Crocoll, S.T. 1994. Red-shouldered hawk (Buteo lineatus). In A. Poole and F. Gill, eds. The
Birds of North America, No. 107. Academy of Natural Sciences, Philadelphia, and
American Ornithologists’ Union, Washington, DC.
Drexler, J.Z. and B.L. Bedford. 2002. Pathways of nutrient loading and impacts on plant
diversity in a New York peatland. Wetlands. 22:263-281.
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REFERENCES CITED
Faber, M. 2002. Soil survey of Dutchess County, New York. Natural Resources
Conservation Service. National Cooperative Soil Survey, US Department of Agriculture.
Washington, DC. 356 p. + maps.
Fisher, D.W., Y.W. Isachsen, and L.V. Rickard. 1970. Geologic map of New York (Lower
Hudson Sheet). Map and chart series 15. 1:250,000 scale, 100 ft. contour. New York
State Museum and Science Service, Albany.
Godin, A.J. 1977. Wild mammals of New England. Johns Hopkins University Press,
Baltimore. 304 p.
Hill, N.P. and J.M. Hagan. 1991. Population trends of some northeastern North American
landbirds: A half-century of data. Wilson Bulletin 103(2):165-182.
Jones, A.L. and P.D. Vickery. 1995. Distribution and population status of grassland birds in
Massachusetts. Bird Observer 23(2):89-96.
Klemens, M.W. 2001. Bog turtle conservation zones. Appendix A in bog turtle (Clemmys
muhlenbergii), northern population, recovery plan. U.S. Fish and Wildlife Service.
Hadley, Massachusetts. 103 p.
Klemens, M.W. 2005. Amphibians and reptiles of the proposed Dover Knolls development
site, Town of Dover, Dutchess County, New York: Existing conditions. Michael W.
Klemens, LLC. Ridgefield, CT.
Kiviat, E. 1988. Significant habitats of the Town of Dover, Dutchess County, New York.
Report to Town of Dover Planning Board. Hudsonia Ltd., Annandale, N.Y. 46 p.
Kiviat, E. and G. Stevens. 2001. Biodiversity assessment manual for the Hudson River
estuary corridor. New York State Department of Environmental Conservation, Albany.
508 p.
Merritt, J.F. 1987. Guide to mammals of Pennsylvania. University of Pittsburgh Press,
Pittsburgh. 408 p.
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REFERENCES CITED
Miller, N.A. 2005. Bird surveys at the proposed Dover Knolls development site, Town of
Dover, Dutchess County, New York: Existing conditions. Report prepared for Michael
W. Klemens, LLC. Ridgefield, CT.
Murphy, D. 1998. Fish and crayfish: list of species identified during the 1997 field season in
the Great Swamp. Wildlife Conservation Society. Bronx, NY.
Panno, S.V., V. A. Nuzzo, K. Cartwright, B. R. Hensel, and I. G. Krapac. 1999. Impact of
urban development on the chemical composition of ground water in a fen-wetland
complex. Wetlands. 19: 236-245.
Richburg, J.A., W.A. Patterson III, and F. Lowenstein. 2001. Effects of road salt and
Phragmites australis invasion on the vegetation of a western Massachusetts calcareous
lake-basin fen. Wetlands. 21:247-255.
Robbins, C.S. 1980. Effect of forest fragmentation on breeding bird populations in the
Piedmont of the Mid-Atlantic region. Atlantic Naturalist 33:31-36.
Semlitsch, R.D. 2000. Size does matter: The value of small isolated wetlands. National
Wetlands Newsletter 22(1):5-6,13.
Semlitsch, R.D. and J.R. Brodie. 1998. Are small, isolated wetlands expendable?
Conservation Biology 12: 1129-1133.
Vickery, P.D. 1994. Birds of the grasslands. Sanctuary 33(5):26-27.
Wilcove, D.S. 1985. Nest predation in forest tracts and the decline of migratory songbirds.
Ecology 66(4):1211-1214.
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APPENDIX A
Appendix A. Explanation of ranks of species of conservation concern listed in the report.
Explanations of New York State ranks and New York Natural Heritage Program ranks are
from the New York Natural Heritage Program website, consulted December 3, 2004.
New York State Ranks
The following categories are defined in regulation 6NYCRR part 193.3 and apply to New York State
Environmental Conservation Law section 9-1503.
E
Endangered Species. Any species which meets one of the following criteria: species with 5 or fewer
extant sites or fewer than 1,000 individuals; species restricted to fewer than 4 USGS 7 ½ minute
topographical maps; or species listed as endangered by the U.S. Department of the Interior, as
enumerated in the Code of Federal Regulations 50 CFR 17.11.
T
Threatened Species. Any species which meets one of the following criteria: species with 6 to 20
extant sites or 1,000-3,000 individuals; species restricted to not less than 4 or more than 7 USGS 7 ½
minute topographical maps; or species listed as Threatened by the United States Department of the
Interior, as enumerated in the Code of Federal Regulations 50 CFR 17.11.
SC
Special Concern Species: Those species which are not yet recognized as endangered or threatened,
but for which documented concern exists for their continued welfare in New York. Unlike the first
two categories, species of special concern receive no additional legal protection under Environmental
Conservation Law section 9-1503.
New York Natural Heritage Program Ranks (Statewide)
S1
Critically imperiled in NY State because of extreme rarity (5 or fewer sites or very few remaining
individuals) or extremely vulnerable to extirpation from NY State due to biological factors.
S2
Imperiled in NY State because of rarity (6-20 sites or few remaining individuals) or highly vulnerable
to extirpation in NY State due to biological factors.
S3
Rare in NY State (usually 21-100 extant sites).
SH
Historical. No extant sites known in New York State but it may be rediscovered.
Regional Status (Hudson Valley)
RR
Hudsonia has compiled lists of native plants and animals that are rare in the Hudson Valley but
do not appear on statewide or federal lists of rarities (Kiviat and Stevens 2001). We use ranking
criteria similar to those used by the NYNHP, but we apply those criteria to the Hudson Valley
below the Troy Dam. Our regional lists are based on the extensive field experience of biologists
associated with Hudsonia and communications with other biologists working in the Hudson
Valley. These lists are subject to change as we gather more information about species
occurrences in the region. Species with New York State or New York Natural Heritage
Program ranks are presumed to be regionally rare also, but are not assigned a regional rank.
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APPENDIX B
Appendix B. Qualifications of Hudsonia personnel.
Erik Kiviat, Ph.D.
Science Director
Erik has studied the plants and animals of the region for 35 years and has authored over 80 publications and 125
technical assistance reports on wetland ecology, rare species conservation, habitat ecology, introduced species,
the Hudson River, and other subjects. Erik is author of The Northern Shawangunks: An Ecological Survey,
Hudson River East Bank Natural Areas, and Hackensack Meadowlands, New Jersey, Biodiversity: a Review
and Synthesis, and co-author of the Biodiversity Manual for the Hudson River Estuary Corridor. He is a
Certified Wetland Scientist, Certified Ecologist, and Certified Wildlife Biologist. Erik is a co-founder of
Hudsonia, and professor of environmental studies in the Graduate School at Bard College.
Gretchen Stevens, B.S.
Botanist, and Director of the Biodiversity Resources Center
Gretchen has 25 years’ experience in remote sensing, habitat assessments, habitat mapping, rare plant surveys,
and other field biology in the Northeast and elsewhere in the U.S. She is co-author of the Biodiversity Manual
for Hudson River Estuary Corridor, and A Beginner’s Guide to Wild Flowers of the Northeast, and has authored
numerous technical reports on biological assessments, rare plant surveys, and other subjects. Gretchen manages
the GIS laboratory at Hudsonia, curates the Bard College Field Station Herbarium, and supervises the Habitat
Mapping Program and the Biodiversity Education Program of the BRC.
Spider Barbour, B.S.
Ecologist
Spider has over 30 years' experience studying the biodiversity of southeastern New York, and has worked for
Hudsonia since 1981. With expertise in general ecology, botany, entomology and herpetology, he has authored
or co-authored numerous technical reports on biological assessments, rare plant surveys, and other subjects. As
an independent biologist, Spider has performed many types of surveys for clients including West Point Military
Academy, Palisades Interstate Parks Commission, The Nature Conservancy, New York-New Jersey Trail
Conference, New York State Museum, New York Natural Heritage Program, Harlem Valley Rail Trail
Association, and Scenic Hudson. Spider is co-author of Wild Flora of the Northeast, and of the bi-weekly
Nature Walk column in the Woodstock Times.
John T. Sullivan, B.S.
Biologist
John earned a B.S. in Plant Science from Cornell University, and has nearly 7 years experience conducting
biological inventories, habitat assessments, wildlife radiotelemetry and monitoring, and rare species surveys in
the Hudson Valley for several organizations including the New York Natural Heritage program, Hudsonia, The
Nature Conservancy and private consulting firms. Since joining Hudsonia in 2003, he has assisted with the
Blanding’s turtle habitat mapping project in southern Dutchess County, led the Fishkill Creek corridor habitat
mapping project in the towns of Beekman, LaGrange, and Fishkill, and worked on several other biological
assessment and habitat mapping projects in the Hudson Valley.
Hudsonia Ltd., © 2005
N
W
500
E
S
0
1000
0
500
1000
Scale 1:20,000
1000
2000
3000
1500
4000
5000
2000 Meters
6000 Feet
Figure 1. Location of the "Dover Knolls" study site, Town of Dover, Dutchess County N.Y.
#
Habitats and Developed Areas
calcareous wet meadow
constructed pond
cultural
developed
emergent marsh
fen
hardwood & shrub swamp
intermittent woodland pool
marble knoll
oak heath barren
red cedar woodland
river
shrubby oldfield
upland conifer forest
upland deciduous forest
upland meadow
upland mixed forest
waste ground
wet meadow
#
Y
N
W
200
600
Scale 1:10,000
0
200
0
600
400 Meters
E
calcareous crest, ledge, & talus
S
crest, ledge, & talus
1200 Feet
ravine
stream
Figure 2a. Habitats west of Route 22 on the "Dover Knolls" site, Town of Dover,
Dutchess County, N.Y. Habitats identified and mapped by Hudsonia Ltd, 2005.
#
Y
spring or seep
#
Y
N
W
E
S
#
Y
#
Y
#
Y
Scale 1:10,000
200
0
600
200
0
400 Meters
600
1200 Feet
#
Y
#Y
Y
#
#
Y
Figure 2b. Habitats east of Route 22 on the "Dover Knolls" site, Town of Dover, Dutchess County, N.Y.
Habitats identified and mapped by Hudsonia Ltd, 2005. See Figure 2a for key to habitats and developed areas.