Schmidt, Kirsten M.; Menakis, James P.; Hardy, Colin C.; Hann, Wendel J.; Bunnell, David L. 2002. Gen. Tech. Rep. RMRS-GTR-87. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 41 p. + CD.

We produced seven coarse-scale, 1-km2 resolution, spatial data layers for the conterminous United States to support national-level fire planning and risk assessments. Four of these layers were developed to evaluate ecological conditions and risk to ecosystem components: Potential Natural Vegetation Groups, a layer of climax vegetation types representing site characteristics such as soils, climate, and topography; Current Cover Type, a layer of current vegetation types; Historical Natural Fire Regimes, a layer of fire frequency and severity; and Fire Regime Current Condition Class, a layer depicting the degree of departure from historical fire regimes, possibly resulting in alterations of key ecosystem components.

The remaining three layers were developed to support assessments of potential hazards and risks to public health and safety: National Fire Occurrence, 1986 to 1996, a layer and database of Federal and non-Federal fire occurrences; Potential Fire Characteristics, a layer of the number of days of high or extreme fire danger calculated from 8 years of historical National Fire Danger Rating System (NFDRS) data; and Wildland Fire Risk to Flammable Structures, a layer of the potential risk of wildland fire burning flammable structures based on an integration of population density, fuel, and weather spatial data.

This paper documents the methodology we used to develop these spatial data layers. In a Geographic Information System (GIS), we integrated biophysical and remote sensing data with disturbance and succession information by assigning characteristics to combinations of biophysical, current vegetation, and historical fire regime spatial datasets. Regional ecologists and fire managers reviewed and refined the data layers, developed succession diagrams, and assigned fire regime current condition classes. "Fire Regime Current Conditions" are qualitative measures describing the degree of departure from historical fire regimes, possibly resulting in alterations of key ecosystem components such as species composition, structural stage, stand age, canopy closure, and fuel loadings. For all Federal and non-Federal lands, excluding agricultural, barren, and urban/developed lands, 48 percent (2.4 million km2) of the land area of the conterminous United States is within the historical range (Condition Class 1) in terms of vegetation composition, structure, and fuel loadings; 38 percent (1.9 million km2) is moderately altered from the historical range (Condition Class 2); and 15 percent (736,000 km2) is significantly altered from the historical range (Condition Class 3). Managers can use these spatial data to describe regional trends in current conditions and to support fire and fuel management program development and resource allocation.