Download Title: Fine-scale and Microhabitat Factors Influencing Terrestrial

Title: Fine-scale and Microhabitat Factors Influencing Terrestrial Amphibian Occupancy
and Diversity in Low-elevation Old Growth Forest
Introduction:
The distribution of species in a forest ecosystem is a function of abiotic and biotic factors.
An understanding of the mechanisms that drive biological diversity in forested systems is crucial
for the preservation of species and management of ecosystems. Examining patterns in wholeecosystem biodiversity (α-diversity) with respect to environmental factors requires tremendous
resources and often is infeasible for land managers and researchers. Therefore, employment of
surrogate species to serve as proxies for α-diversity is often necessary. Taxa likely to exhibit
faithful distributional patterns to such factors are those with limited dispersal capabilities, low
reproductive success, and sensitivity to environmental conditions. Indeed one such group,
amphibians, is particularly responsive to environmental gradients. They are acutely sensitive to
contaminates, water and soil chemistry, and dewatering because of their highly permeable skin.
Additionally, as ecotherms, they rely on landscape structure, thermal and hydrologic regimes,
and prey availability – making them especially sensitive to habitat quality. More specifically,
terrestrial salamanders are purportedly effective indicator species for monitoring the health and
integrity of North American forests.
Terrestrial salamanders are a vital component in temperate forest ecosystems of the
eastern US, and mesic forests of the Appalachian Mountains contain the greatest diversity of
them in the world. However, a lack of data exists documenting species-specific responses to finescale natural environmental variables, especially in sparsely distributed mature forest of central
Appalachian. Furthermore, because terrestrial salamander communities are known to have
differential responses to environmental gradients based on species-specific niche requirements,
the degree of endemism in terrestrial Appalachian salamanders limits applicability of species
with known responses. It is, therefore, crucial to understand the relationship of terrestrial
amphibians to natural environmental gradients in Appalachia. The objectives of this study are to
determine what abiotic (aspect; slope; elevation; soil moisture, pH, and nutrient content) and
biotic (vegitative composition) factors affect fine-scale distribution and abundance of terrestrial
amphibians.
We plan to address these objectives by conducting extensive terrestrial amphibian
surveys, and quantifying fine-scale habitat parameters and geospatial features of Lilley Cornett
Woods, a forest in the Cumberland Plateau-region of south-eastern Kentucky, containing several
mixed mesophytic old growth stands. Owing to its rich amphibian diversity, lack of
anthropogenic disturbance, and heterogeneous landscape and vegetative structure, Lilley Cornett
Woods serves as an exemplary location to conduct this study. This study will not only uncover
relationships of biodiversity in forested ecosystems that can help aid in management and
conservation decisions, but also contribute important life-history and ecological information to
the current knowledge of a group of organisms that are currently experiencing precipitous
declines on a global scale.
Methods:
The Lilley Cornett Woods (LCW) Appalachian Ecological Research Station (Letcher
County, KY, USA) is a 223-ha tract of land in the Cumberland Plateau. My study will take place
in Short Trail Stand (STS), a mixed mesophytic old growth stand of LCW. STS contains 57
circular 0.04-ha sample plots, originally established in 1975, representing approximately 10% of
the total upland area in STS. Sample plots were created along vertical ravines (concave slope
shape) and ridges (convex slope shape) for each slope position (lower [<365 m], middle [365 m
– 427 m], upper, and ridge [> 1480 m]). Two sampling events will occur during three seasons
(spring, summer, and fall) of 2016 at all 57 sites, resulting in six replications at each site (two per
season). A subset of the 57 sites will be selected randomly for an additional sampling event
(three per season) each season to calculate probability of detection for terrestrial salamander
species in STS.
To eliminate sampling bias, increase replicability, and ensure plots are sampled
thoroughly, a simple random sample design will be used, wherein the direction of linear visual
encounter survey (VES) transects at each plot are determined by randomly selecting a bearing
between 0° and 180°, with the midpoint of all transects pivoting and centering on the plot
marker, which is positioned at the geometric center of each sample plot. A 50x6-m transect will
be established and searched opportunistically for amphibians under all natural cover (rocks and
woody debris. Visual encounter surveys will be conducted at every site during the spring,
summer, and fall of 2016–2017 (n=6), during times of day most advantageous for encountering
amphibians (0800 – 1100 hrs and 1500 – 1900 hrs).
Quantification of forest canopy openness will be achieved using hemispherical canopy
photography, wherein a 180° fish-eye lens is used to capture canopy structure, as well as canopy
light transmission. Fallen coarse woody debris (CWD; logs and branches; excluding snags)
larger than 20 cm in diameter will be measured at each 50x3-m VES transect. Leaf litter density
will be determined by measuring leaf-litter depth and wet-mas. Soil moisture, pH, and
temperature will be measured during each quadrat-sampling event. Soil pH will be measured at
the upper-most horizon below leaf-litter. Aspect and elevation of each plot will be collected
using ArcGIS 10.1. The slope of each plot will be measured using a clinometer.
Amphibian count data will be used to calculate species richness and evenness, and
biological diversity indices (Simpson and Shannon-Wiener) for each site (n=60). Geospatial data
(aspect, slope, and elevation), and environmental data (soil pH, moisture, and temperature;
CWD, leaf-litter density, and canopy openness) will then be used in regression models as
predictor variables for amphibian diversity metrics using SPSS 22.