Wednesday, August 4, 2010

PS 52-45: 43 years of fire in sagebrush steppe

Andréa L. Kuchy and Stephen C. Bunting. University of Idaho

We explored the relationships between fire and climate by investigating a range of potentially important climatic variables in an effort to understand the relationship between seasonal climate patterns and large fire (5000+ hectares) events over four decades. There are few studies of fire history in the sagebrush steppe and none that examine the changes in occurrence and size of large fires and consecutive climatic conditions. We used historic records from 1960 to 2003 to explore regime characteristics of large fires and total fires at multiple spatial scales across the sagebrush steppe ecoregions.

Shifts in the fire regime between 1960 to 1982 and 1983 to 2003 were characterized by an increase in the total number of large fires and more than doubling in total area burned by large fires during the second half of the study period. Total current year maximum temperature was positively correlated with fire size at the broadest scale, although these effects were not observed for precipitation or at finer spatial scales. Results indicate that high air temperatures and exotic annual grasses combined provide an environment favorable to large fire events. These results and the projected trend toward warmer, drier growing seasons and summers suggest that sagebrush steppe systems are likely to continue to experience an increase in large fires in the future.