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U.S. Geological Survey - Gap Analysis Project Species Habitat Richness

May 10, 2019

The Species Richness Maps included here are based on the Gap Analysis Project (GAP) habitat maps, which are predictions of the spatial distribution of suitable environmental and land cover conditions within the United States for individual species. Individual species habitat distribution models were summed to create the total richness for each vertebrate taxa. The summing process was coded in Python 2.7 and employed the arcpy module for geoprocessing steps. The code is documented in the log file which is included in the Sciencebase item along with the richness data for each taxa (See processing steps for file names and sciencebase urls). Mapped habitat distribution areas represent places where the environment is suitable for the species to occur (i.e. suitable to support one or more life history requirements for breeding, resting, or foraging), while areas not included in the map are those predicted to be unsuitable for the species. We developed habitat maps using a deductive modelling process by compiling information on species habitat associations into a habitat relationship database. Information was compiled from the characterizations of species habitat in books, databases and primary literature, as well as from expert opinion. We used habitat descriptions to determine which of the National GAP Land Cover ecological systems and land use classes the species could occur in. The dataset contains over 580 map classes and represents detailed and nationally consistent data on vegetation in the United States and provides the ecological context necessary to build fine grain habitat associations. For many species, we used additional environmental variables including elevation, proximity to water features, proximity to wetlands, level of human development, forest ecotone width and forest edge. For a full description of the species habitat distribution modeling see: Gergely,K.J., Boykin, K.G., McKerrow, A.J., Rubino, M.J., Tarr, N.M., and Williams, S.G., 2019, Gap Analysis Project (GAP) terrestrial vertebrate species richness maps for the conterminous U.S.: U.S. Geological Survey Scientific Investigations Report 2019 5034, https://doi.org/10.3133/sir20195034.