A national inventory of the existing vegetation across the U.S. has been central to the missions of both the Landscape Fire and Resource Management Planning Tools Project (LANDFIRE) and the National Gap Analysis Program. Recently these two programs have come together to collaborate on the next generation highly detailed land cover map for the U.S. This collaboration leverages the mapping and inventory to meet needs for both fire and fuels management, as well as for wildlife habitat conservation planning. While the initial mapping effort focused on the Ecological Systems Classification, a 2011 update and a 2016 remap are incorporating a crosswalk to the U.S. National Vegetation Classification specific to the current hierarchy that was formally released in 2016. The crosswalk to the hierarchical structure of the USNVC allows for scaling of the map legend in a standardized approach.
There are 551 natural vegetation classes represented in the GAP/LANDFIRE National Terrestrial Ecosystems Map for the conterminous U.S. The crosswalk allows for the aggregation of the mapped clasess into the hierarchical structure of the USNVC; specifically, the ecological systems are crosswalked to the middle and upper levels of the USNVC. For example three of the map units, the East Gulf Coastal Plain Southern Loess Bluff Forest, West Gulf Coastal Plain Mesic Hardwood Forest and the East Gulf Coastal Plain Southern Mesic Slope Forest are crosswalked into a single USNVC Group, the Southern Mesic Beech – Magnolia – Oak Forest Group. That group provides the ecological context at a regional scale for the areas mapped as those three forest types. The natural vegetation classes are aggregated into 240 groups, 112 macrogroups, 51 divisions, 22 formations, 13 subclasses and 6 classes. For the three map units listed, the middle and upper higher levels of the hierarchy are the Southern Mixed Mesic Mixed Broadleaf Forest Macrogroup, Southeastern North American Warm Temperate Forest & Woodland Division, Warm Temperate Forest & Woodland Formation, Temperate and Boreal Forest & Woodland Subclass, and the Forest & Woodland Class.