PARENT SESSION
Poster Session 2: Forest Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Simulating effects of fire on forest composition and structure in the Pacific Northwest.
Busing, Richard1, Solomon, Allen2, 1 U.S. Geological Survey, Corvallis, OR2 U.S. Environmental Protection Agency, Corvallis, OR
ABSTRACT- The FORCLIM forest gap model has successfully projected forest composition across broad climatic gradients in western Oregon. Now, we have modelled fire regime effects to improve agreement between simulated and actual tree species composition. The individual-based model was modified for simulation of ground fires as well as crown fires. Each tree species was placed in one of four categories of mortality response to fire severity. Typically, simulated susceptibility of individuals to fire decreased as tree diameter increased. Simulated fire regimes, characterized by the frequency of light fires and the frequency of severe fires, were based on USDA Forest Service studies. Seven forested ecoregions in western Oregon were modeled with each ecoregion having a unique fire regime. Fire tended to reduce stand basal area and, under some regimes simulated, caused strong changes in composition. Simulated catastrophic fire reduced stand biomass, basal area and leaf area. Non-catastrophic fires influenced the regeneration success of species thereby affecting composition. Regimes with frequent, low-severity fires (e.g., dry Oregon white oak and ponderosa pine forests) had particularly strong and realistic effects on species composition.
Key words: fire disturbance, forest dynamics, Pacific Northwest