INTERMOUNTAIN WEST LIGHTNING-CAUSED FIRES - CLIMATIC PREDICTORS OF AREA BURNED

An increase in continuous fine fuels promoted by the expansion of aggr essive annual exotic grasses in the Intermountain West has altered the region's fire regimes, with both ecologic and economic ramifications. I examine the predictive nature of seasonal climatic variables, seaso nal precipitation and temperature data up to 2 years before the actual summer fire season, to forecast the area burned by lightning-caused f ires during the 13 fire seasons (1980-1992). Five climatically-distinc t regions in the shadscale, sagebrush-steppe, sagebrush-semidesert, an d open pine with grass communities of California, Idaho, Nevada, Orego n, and Utah were included in the analysis. The amount of associated va riance ranged from 43 to 62% between area burned and seasonal climatic variables. Results show that the seasonal climate that promotes fires is distinctly regional, even in areas of similar vegetation. However, the area burned increases primarily when the climate favors the growt h of annual grasses over perennial species, or promotes either cooler or wetter conditions during the previous summer (fire) seasons. These results provide land managers with additional information for making d ecisions on presuppression activities.