U.S. Joint Fire Science Program


Date of this Version


Document Type



Fire Science Brief, Issue 28, December 2008


US government work.


The massive Cedar and Otay fires of 2003 in southern California offered researchers an unexpected opportunity to examine the effects of fi re on mammal communities. Jay Diffendorfer and his colleagues had already been sampling small mammal communities at the Rancho Jamul Ecological Reserve where the Otay fi re broke out. There the researchers could see the difference in small mammal communities, pre- and postfire and the impacts of postfire, exotic grass invasion. At the Cleveland National Forest, where the Cedar fire occurred, the team examined whether the size and severity of the fire affected small mammal communities, as well as carnivores and bats. Fire changed small mammal communities in both study areas—probably because of the subsequent shift in postfi re vegetation. In general, after the fire, species specializing on open, grassy areas were present, while in unburned areas, there were more shrub-specializing species. The research suggests that the frequency and intervals of fire are likely much more important than fire severity and size, because of the potential to convert the vegetation from shrubs to grassy habitat dominated by non-natives. Since vegetation drives mammal diversity, management goals that focus on preserving native vegetation may be the key to preserving animal diversity.