Short-term effects of fuel treatments on fisher habitat in the Sierra Nevada, California

Abstract

The characteristics of western forests have changed as a result of fire suppression and fuel reduction treatments have become a public land management priority. The effects of these treatments on wildlife habitat, however, have received limited attention. The fisher (Martes pennanti) is a species of concern in California and is vulnerable to fuels treatments due to its association with dense forests and use of large and old trees as resting sites. We evaluated the effect of fuels treatments by estimating predicted resting and foraging habitat at two sites in the Sierra Nevada that are part of the national Fire and Fire Surrogate Study. One site included three treatments (mechanical harvest, prescribed fire, and mechanical harvest plus prescribed fire) and the other included early and late-season prescribed fire; both sites included control treatments. We sampled vegetation before and after treatment application to estimate variables that were included in resource selection probability functions. Predicted resting habitat was significantly lower for mechanical plus fire treatments, but the control did not differ from the fire only or the mechanical only treatment. Late, but not early, season burns had significant impact on predicted resting habitat. Reductions in canopy cover affected predicted resting habitat directly. Fisher foraging habitat, unlike resting habitat was unaffected by treatments at either site. Within a stand, a number of management actions can mitigate the potentially negative short-term effects of fuels treatments on fisher habitat. Evaluating the effects of fuels management at the resting site, home range and landscape scales will be necessary to administer a treatment program that can address fuel accumulation while also restoring and maintaining fisher habitat.