Timber Harvest and Black Bear Population Dynamics in a Southern Appalachian Forest

Habitat capability models are frequently used in long-term land management planning to evaluate the effects of management alternatives on wildlife populations. We believe that the relationships between timber harvest operations and black bear (Ursus americanus) population dynamics in the southern Appalachians make habitat capability models alone inadequate to predict long-term population response to timber harvest. An explicit consideration of population dynamics is necessary. Most timber in the region is harvested by clear-cutting, which requires an extensive road system and subsequently increases the vulnerability of bears to hunters. We present a simple deterministic model in which habitat dynamics are linked to population dynamics in 2 ways. The 1st is through the classic notion of carrying capacity, the 2nd is through a vulnerability factor that depends on local road density, which is in turn a function of the amount of clear-cutting that has occurred. We simulate the dynamics of a bear population in an area of Pisgah National Forest under 3 management regimes that facilitate comparison of the effects of different rotation intervals on the population. We conclude that some timber harvest regimes may improve the biotic capability of bear habitat in terms of carrying capacity, but that these benefits may be easily outweighed by the concommitant increase in vulnerability to hunting. Under present conditions hunting is a stronger influence on the population than is biotic habitat quality.