GAP- VAFWIS Database Descriptions
Land cover categories, primarily vegetation types, were derived from Landsat Thematic Mapper satellite imagery. The base images were acquired around 1992. Other data used in the classification include elevation models, relative phenological index, and National Wetland Inventory. The resulting classification has a 30m cell size and is clipped to the boundary of Virginia. The purpose of this product is to depict the land cover of Virginia and to provide a base habitat surface with which to produce vertebrate species distribution models.
Predicted Species Distribution
Predicted species distribution identifies areas where a species may potentially occur. This prediction is based on known range (by county) and known habitat use. Both county range and habitat use were determined through BOVA species information. Habitat use was matched to the habitat categories in the VAGAP Habitat layer. The result is a raster image that shows areas of potentially suitable habitat within a species' range.
Species richness is the total number of species that are predicted to potentially occur within an area. Overall species richness is the sum of all VAGAP predicted species distribution. There are 568 terrestrial vertebrate species that were modeled as part of the Virginia Gap Analysis. However, the greatest number of species having potentially suitable habitat on the same area is 341 (southeast Virginia). This is the most species rich area in Virginia. The least species rich area, or area with the lowest number of species with potentially suitable habitat, is 0. This occurs on barren areas in some parts of the Commonwealth.
Amphibian species richness is the total number of amphibian species that are predicted to potentially occur within an area. There are 78 amphibian species that were modeled as part of the Virginia Gap Analysis. However, the greatest number of amphibians having potentially suitable habitat on the same area is 33. The southeast is the most species rich area in Virginia. The least species rich area, or area with the lowest number of species with potentially suitable habitat, is 0. This occurs on lower lands in Northern Virginia.
Reptile species richness is the total number of reptile species that are predicted to potentially occur within an area. There are 67 reptile species that were modeled as part of the Virginia Gap Analysis. However, the greatest number of amphibians having potentially suitable habitat on the same area is 45. Southeastern Virginia is the most species rich area for reptiles. The least species rich area, or area with the lowest number of species with potentially suitable habitat, is 7. This occurs on developed lands in southwestern Virginia.
Bird species richness is the total number of avian species that are predicted to potentially occur within an area. There are 317 birds species that were modeled as part of the Virginia Gap Analysis, the largest of any taxonomic group. However, the greatest number of birds having potentially suitable habitat on the same area is 252. Southeastern Virginia and the Easternshore are the most species rich areas for birds. The least species rich area, or area with the lowest number of species with potentially suitable habitat, is 32. Lower avian species richness tends to occurs in the piedmont.
Mammals species richness is the total number of mammal species that are predicted to potentially occur within an area. There are 106 mammal species that were modeled as part of the Virginia Gap Analysis. However, the greatest number of mammals having potentially suitable habitat on the same area is 61. The mountains of northwestern Virginia are the most species rich area for mammals. The least species rich area, or area with the lowest number of species with potentially suitable habitat, is 0. This occurs on open water in southeastern Virginia.
Species Richness - T&E Species
T&E species richness is the total number of federal or state threatened or endangered species (listed species) that are predicted to potentially occur within an area. There are 38 listed or T&E species that were modeled as part of the Virginia Gap Analysis. However, the greatest number of T&E species having potentially suitable habitat on the same area is 15. Southwestern Virginia are the most species rich area for T&E species. The least species rich area, or area with the lowest number of T&E species with potentially suitable habitat, is 0. This occurs in Buchanan County.
Underprotected Richness is the total number of species, considered "underprotected" from the Gap Analysis, predicted to potentially occur within an area. Each species predicted potential distribution was compared with information about protected lands. Protected lands are state, federal, and local government owned lands with some mandate for protecting open space. Protected lands were derived from Virginia Department of Conservation and Recreation's Conservation Lands Database. Species with less than 10% of their predicted potential distribution in protected areas were considered "underprotected". Out of 568 species assessed in the Virginia Gap Analysis, 148 were underprotected (~26%). The Underprotected layer shows where the most underprotected species are likely to occur. The highest underprotected richness, 76 species, occurs in southeastern Virginia. The lowest underprotected species richness is in the mountains of western Virginia.