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Existing vegetation (EV) is the floristic composition and vegetation structure occurring at a given location at the current time. This feature set depicts the existing vegetation of the forests and grasslands of the Southwestern Region at the mid-scale as four products - life form, dominance type map units, canopy cover map units, and size map units at the time the source satellite images were acquired. Multi-season satellite images (Landsat-5 and/or Landsat ETM+) along with ancillary and derived data sets (e.g., Digital Elevation Models and spectral indices) were used to model vegetation at the mid-scale level, suitable for presentation at a scale of approximately 1:100,000. The mapping process conformed to national guidelines developed by the Forest Service as defined in the Existing Vegetation Classification and Mapping Technical Guide Version 1.0 (USDA Forest Service Gen. Tech. Report WO-67). A combination of pixel- and object-based classifiers were used to attribute polygons with life form, dominance type, canopy cover class, and size class. Polygons with shared attributes were subsequently aggregated for each product to the map units presented here. |