MAPPING FIRE REGIME CONDITION CLASS : A METHOD FOR WATERSHED AND PROJECT SCALE ANALYSIS

Fire regime and associated condition class mapping have provided key data for development of cohesive strategies for restora­ tion of fire-adapted ecosystems and for the National Fire Plan within the U.S. Department of Agriculture, Forest Service and U.S. Department of Interior land management agencies. Fire regime condition class (FRCC) provides data that can be used to infer risk to ecosystem sustainability and risk of uncharacteristic wildland fire behavior and effects. These spatial data when combined with human community locations can be used to identify communities at risk from uncharacteristic wildland fire. When combined with spatial data on air, native species, and water, opportunities for fuel management and fire use can be iden­ tified that benefit local communities and minimize risk or potentially enhance resources and sustainability. Scenarios of spa­ tial prioritization, fire use and fuel management levels, and associated resource and risk reduction effects can be evaluated by combining these data with tools to model future outcomes. In combination with vegetation composition and structure, under­ standing of FRCC provides the framework for design of projects on the ground. A method for coarse-scale (1-km2) mapping of FRCC and associated fire management data across the conterminous U.S. has been developed and applied. However, no method had been developed and applied for finer-scale (30-m) watershed and project mapping of FRCC and associated prioritization and planning data. The study described in this paper used data from selected landscapes in the western U.S. to develop a method for FRCC analysis at watershed and project scales. Results indi­ cate that the definitions and methods for mapping and understanding fire regime condition classes should change with scale of application. At a coarse scale, such as that used for national, regional, and state levels of prioritization and planning, the variation of fire regime frequency and severity can be collapsed into broad categories, and condition class departure can be assigned via rule sets. The large pixel area accounts for natural variation within and between fire regimes and condition class­ es that occurs across multiple stands or patches. At the finer scales (<1 km2) of watershed assessment and project analyses, any one of a number of the vegetation–fuel classes characteristic of the natural or historical system can occur. Methods at this finer-scale focus on determination of the composition of characteristic classes and the associated variation in fire interval and severity. Standardized steps were developed, which combine available information with ground reconnaissance, and integra­ tion with the “box model. ” keywords: condition class, fire regimes, fuels, natural range of variability, planning, western United States. Citation: Hann, W.J. 2004. Mapping fire regime condition class: a method for watershed and project scale analysis. Pages 70–87 in R.T. Engstrom, K.E. M. Galley, and W.J. de Groot (eds.). Proceedings of the 22nd Tall Timbers Fire Ecology Confer­ ence: Fire in Temperate, Boreal, and Montane Ecosystems. Tall Timbers Research Station, Tallahassee, FL. INTRODUCTION Hardy et al. (2001) and Schmidt et al. (2002) map Fire regime condition class (FRCC) is now a key FRCC and associated information to support nation­ al scale strategic fire and fuels planning using coarsevariable for assessment of wildland fire risk to peo­ scale 1-km2 data for the conterminous United States. ple (communities) and ecosystems in the United They define and map five historical natural fire States. Condition classes, numbered from 1 to 3, repregimes using a rule set approach to unique combi­ resent increasing levels of risk from uncharacteristic nations of biophysical data. The fire regimes, based wildland fire behavior and effects (Hann and Bunnell on Heinselman (1981), Morgan et al. (1996), and 2001, Hardy et al. 2001, Schmidt et al. 2002). Also, Brown (1995), are 0to 35-year frequency with low condition classes are generally equivalent to low, severity (I), 0to 35-year frequency with standmoderate, and high departure from the natural or hisreplacement severity (II), 35to 100+-year frequency torical range of variability (HRV), considered a basewith mixed severity (III), 35to 100+-year frequency line for coarse-filter assessment of risks to ecosyswith stand-replacement severity (IV), and 200+-year tems, habitats, and social values (Morgan et al. 1994, frequency with stand-replacement severity (V). They Hann et al. 1998, Landres et al. 1999). define fire frequency or interval as “the average num­