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Potential Natural Vegetation Groups

The LANDFIRE Rapid Assessment (RA) potential natural vegetation groups (PNVGs) spatial data layer delineates vegetation communities that are likely to exist under the natural range of variability in biophysical environments and ecological processes, including fire and other disturbances. This biophysical classification was based originally on Kuchler’s work (1964), modified during the Coarse-Scale Fire Regime Condition Class (FRCC) Assessment (Schmidt and others 2002), refined in the development of the Interagency FRCC Guidebook (Hann and others 2004), and then further refined during the RA process. In this process, the RA team conducted twelve week-long workshops throughout the conterminous United States to garner input from over 250 local land managers. Experts collaborated to refine the PNVG classification, write PNVG descriptions, model each PNVG to determine reference conditions, and assign mapping rules for each PNVG.

LANDFIRE Rapid Assessment PNVGs were mapped according to the following steps. First, local experts defined mapping rules for each RA PNVG using any combination of the following data sets: Coarse-Scale FRCC Assessment PNVGs (Schmidt and others 2002), ecological regions, precipitation, growing degree days, elevation, aspect, slope, topography, soil texture (percent sand, silt, clay, and coarse), soil depth, and existing vegetation. Second, overlapping and missed areas (in other words, those without PNVG assignments) were resolved based on RA PNVG descriptions, mapping notes, and comparison with other data sets. Lastly, RA PNVGs were rectified to existing vegetation types at the stand level, which involved the reassignment of PNVGs when the two layers did not ecologically agree (such as if an alpine existing vegetation type was assigned a desert PNVG). Reassignment was based on PNVG descriptions, adjacent RA PNVGs along similar ecological gradients, and the limitations and strengths of each of the input layers. This step resulted in one RA PNVG being assigned to each stand.

For more information about RA PNVG descriptions and modeling, please visit the RA Reference Condition Models section of this website.

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Kuchler A. W. 1964. Potential natural vegetation of the conterminous United States (manual and map). Special Publication 36. New York: American Geographical Society. 116 p.

Schmidt, Kirsten M., Menakis, James P., Hardy, Colin C., Hann, Wendel J., and Bunnell, David L. 2002. Development of coarse-scale spatial data for wildland fire and fuel management. General Technical Report RMRSGTR-87. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 41p. Available at: www.fs.fed.us/fire/fuelman.

Hann, Wendel J. et al. 2004. Interagency Fire Regime Condition Class Guidebook. Available at: www.frcc.gov.