Landscape-Level Habitat Modeling
for Amphibians and Reptiles in West Virginia

Introduction
Methods - Model Creation
Methods - Predicted Distribution Mapping
Results
Images

Jacquelyn M. Rowe and Charles B. Yuill
Natural Resource Analysis Center
College of Agriculture and Forestry
West Virginia University, Morgantown, WV 26506

INTRODUCTION

Certain amphibians and reptiles rely on the use of small surface water and wetlands features which cannot be adequately captured at the Gap Analysis mapping scale for land cover features. These species may be more strongly associated with surface water features and riparian areas than with any particular cover type. In order to more accurately model the distributions of these species, a separate, highly detailed land cover map focused on wetland, riparian, and surface water features has been developed by the West Virginia Gap Analysis project (WV-GAP).

Species which require the use of the wetland/riparian/surface water model are determined from the WV-GAP species habitat relationship database. If the database record for a particular species indicates no associations with specific terrestrial cover types(forested, woodland, shrubland, or other), but does include one or more associations with specific wetland or surface water features, the species requires the use of this special land cover model.

METHODS - MODEL CREATION

The original source for the wetlands was the National Wetlands Inventory (NWI) data for West Virginia, with wetlands classified according to Cowardin et al. (1979).All NWI wetland features were buffered to 30 m. The source of data for streams and associated riparian areas was the Environmental Protection Agency's (EPA's) River Reach version3 coverage. Small ponds in the Reach coverage were extracted as polygons and buffered to 30 m , similar to NWI wetlands. All streams in the Reach coverage were buffered according to stream order:

1st, 2nd order - 30 m either side of stream

3rd, 4th order - 60 m

5th order - 120 m

6th order - 150 m

wide rivers with both shorelines - 300 m

Wetlands and riparian features were combined with a grid of forested land cover from the EPA's Multi-Resolution Land Characteristics Consortium (MRLC) data for WV. (All WV-GAP satellite imagery has been registered to the MRLC data, which will be used as a forest/non-forest mask in vegetation classification and eventual edge-matching). The final model indicates type of wetland or riparian feature, and forest or non-forest land cover. The point locations of springs and caves buffered to 30 m were also used in the final distribution mapping process.

 This table lists the different habitat types mapped and their original source(s):

METHODS - PREDICTED DISTRIBUTION MAPPING

The predicted distribution of each species requiring the use of the model was mapped using the following steps:

1. Created a matrix of presence/absence for each species in each habitat type (see table above for habitat types).
2. Created a one-to-many database link between the habitat types in the presence/absence matrix and the wetland/riparian habitat polygon coverage attribute table.
3. For each species, selected all habitat types used by that species from the matrix. All appropriate habitat type polygons are also selected through the link.
4. Eliminated non-forested polygons, if species is limited to forested areas.
5. Performed further spatial selection to limit selected habitat polygons to those which intersect EMAP hexagons where species is reported to occur.

Species which require use of this model:

** - Not reported in WV-GAP hexagon of occurrence data to date.

RESULTS

A total of 39 species (25 amphibians, 14 reptiles) were modeled using this method. There are 83 species of amphibians and reptiles reported from West Virginia overall. The remaining species distributions will be predicted using the alliance-based land cover map. For each species modeled with this method, a map of appropriate habitat polygons within hexagons of occurrence was produced. These maps show the predicted distribution for each species. The maps are currently under review by a number of species experts around the state. A summary of the total area of each habitat type within the predicted distribution for each species was also calculated. Sample results for two species are shown below:

Longtail Salamander

View image of predicted distribution

Total area of habitat: 207223.57 hectares

Total number of hexagons with species reported: 82

Painted Turtle

View image of predicted distribution

Total area of habitat: 180854.12 hectares

Total number of hexagons with species reported: 40

IMAGES

NWI Wetlands

EPA River Reach

Caves and Springs

Forested Areas

These images show the individual coverages which were combined into the final habitat model through various Arc/INFO GRID operations.

Wetland and Riparian Habitats Map

This image shows the final version of the wetland/riparian/surface water features model. This map was created from merging NWI and EPA River Reach coverages, and reclassifying the resulting coverage to match WV-GAP's habitat types.

Species Richness in Habitat Polygons Map

This image shows the species richness of each habitat polygon in the wetland/riparian/surface water features model. Species richness seems to be highly influenced by the nature of the hexagonal distribution maps.

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