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Alexa McKerrow


Science Analytics and Synthesis

Email: amckerrow@usgs.gov
Office Phone: 919-513-2853
Fax: 919-515-4454
ORCID: 0000-0002-8312-2905

Supervisor: Mark T Wiltermuth
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This layer represents a crosswalk of the GAP/LANDFIRE National Terrestrial Ecosystems 2011 land cover to the Class level of the U. S. National Vegetation Classification (USNVC). At the Class level vegetation types are distinguished based on dominant growth form (for example - Forest & Woodland). In addition to the vegetation types in the map legend there are land use classes (for example - open water, agriculture) that are not a part of the USNVC. Visit these sites for more information about the National Classification, the Federal Geographic Data Committee- Vegetation Subcommittee and the USNVC Standard. These data cover the entire continental U.S. and are a continuous data layer. These raster data have a 30 m...
Categories: Data; Types: Map Service, OGC WMS Layer
This provisional Biogeographic Analysis Package provides an analysis of protection status for ecological systems within Omernik Level III Ecoregions. The ecological system classification defines groups of plant communities that tend to co-occur within landscapes with similar ecological processes, substrates, and/or environmental gradients and is the primary map class used in the Gap Analysis Program (GAP) land cover layer (based on 2001 satellite imagery). This package can be used to identify the ecoregions where ecological systems have the greatest representation in GAP Status 1 and 2 lands (lands managed for the protection of biodiversity) and the ecoregions where ecological systems are the least protected....
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This layer represents a crosswalk of the GAP/LANDFIRE National Terrestrial Ecosystems 2011 land cover to the Division level of the U. S. National Vegetation Classification. At the Division level vegetation types are distinguished by combinations of growth forms, broad diagnostic plant species, and continental differences in mesoclimate, geology, substrates, hydrology, and disturbance regimes (for example - Vancouverian Cool Temperate Forest & Woodland). In addition to the vegetation types in the map legend there are land use classes (for example - open water, agriculture) that are not a part of the USNVC. Visit these sites for more information about the National Classification, the Federal Geographic Data Committee-...
Categories: Data; Types: Map Service, OGC WMS Layer
"GAP distribution models represent the areas where species are predicted to occur based on habitat associations. GAP distribution models are the spatial arrangement of environments suitable for occupation by a species. In other words, a species distribution is created using a deductive model to predict areas suitable for occupation within a species range. To represent these suitable environments, GAP compiled existing GAP data, where available, and compiled additional data where needed. Existing data sources were the Southwest Regional Gap Analysis Project (SWReGAP) and the Southeast Gap Analysis Project (SEGAP) as well as a data compiled by Sanborn Solutions and Mason, Bruce and Girard. Habitat associations were...
Tags: ArcGIS
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Uses direct output files of Aquatic Gap Analysis Program (AGAP) fish distribution models and National Fish Habitat Partnership (NFHP) 2010 Habitat Condition Indicies (HCI) to make summarized conclusions of stream condition and fish biological potential for Level 3 Ecoregions across the Conterminous United States (CONUS). Initial AGAP and NFHP products were represented at the local catchment scale of the National Hydrography Dataset Plus Version 1 (NHDPlusV1). To summarize AGAP and NFHP data into Level 3 EcoRegions a length-weighted average was used (i.e. the cumulative HCI value for each river reach within an ecoregion was weighted by the reach length with the formula (H1*L1+H2*L2...+HX*LX)/(H1+H2...+HX) where...
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