Faunal responses to fire in chaparral and sage scrub in California, USA

Abstract

Impact of fire on California shrublands has been well studied but nearly all of this work has focused on plant communities. Impact on and recovery of the chaparral fauna has received only scattered attention; this paper synthesizes what is known in this regard for the diversity of animal taxa associated with California shrublands and outlines the primary differences between plant and animal responses to fire. We evaluated the primary faunal modes of resisting fire effects in three categories: 1) endogenous survival in a diapause or diapause- like stage, 2) sheltering in place within unburned refugia, or 3) fleeing and recolonizing. Utilizing these patterns in chaparral and sage scrub, as well as some studies on animals in other mediterranean-climate ecosystems, we derived generalizations about how plants and animals differ in their responses to fire impacts and their postfire recovery. One consequence of these differences is that variation in fire behavior has a much greater potential to affect animals than plants. For example, plants recover from fire endogenously from soil-stored seeds and resprouts, so fire size plays a limited role in determining recovery patterns. However, animals that depend on recolonization of burned sites from metapopulations may be greatly affected by fire size. Animal recolonization may also be greatly affected by regional land use patterns that affect colonization corridors, whereas such regional factors play a minimal role in plant community recovery. Fire characteristics such as rate of spread and fire intensity do not appear to play an important role in determining patterns of chaparral and sage scrub plant recovery after fire. However, these fire behavior characteristics may have a profound role in determining survivorship of some animal populations as slow-moving, smoldering combustion may limit survivorship of animals in burrows, whereas fast-moving, high intensity fires may affect survivorship of animals in aboveground refugia or those attempting to flee. Thus, fire regime characteristics may have a much greater effect on postfire recovery of animal communities than plant communities in these shrubland ecosystems.