LANDFIRE 2001 Refresh Existing Vegetation Type (EVT) CONUS

LANDFIRE's (LF) 2001 Existing Vegetation Type (EVT) product represents the current distribution of the terrestrial ecological systems classification developed by NatureServe for the western hemisphere. In this context, a terrestrial ecological system is defined as a group of plant community types that tend to co-occur within landscapes with similar ecological processes, substrates, and/or environmental gradients. See the EVT product page (https://landfire.gov/vegetation/evt) for more information about ecological systems and NVC classifications.
EVT is mapped using decision tree models, field data, Landsat imagery, topography, and biophysical gradient data. Decision tree models are developed separately for tree, shrub, and herbaceous lifeforms which are then used to produce a lifeform specific EVT product. These models are generated for each Environmental Protection Agency (EPA) Level III Ecoregion (https://www.epa.gov/eco-research/ecoregions). Riparian, alpine, sparse, and other site-specific EVTs are constrained by predetermined masks.
The final EVT and Environmental Site Potential (ESP) products are compared and rectified through a series of QA/QC measures. Values of one or more of these data layers are adjusted based on a hierarchical decision tree ruleset to align the respective lifeforms and life-zone of each ESP and EVT category.