LANDSCAPE CHANGE AND HABITAT AVAILABILITY IN THE SOUTHERN APPALACHIAN HIGHLANDS AND OLYMPIC PENINSULA

Abstract

Methods for predicting the ecological impacts of land use change on biodiversity and ecosystem function are needed to guide land planning and resource management decisions. This study explores the consequences of alternative scenarios of land cover change on the abundance and arrangement of potential habitat for a suite of species in the Little Tennessee River Basin (LTRB) in the Southern Appalachian Highlands and the Hoh River Basin (HORB) on the Olympic Peninsula. We addressed two questions: (1) How does land ownership affect the availability of suitable habitat for a variety of species in changing landscapes (and how do restrictions on forest harvest then change habitat availability)? (2) Are species differentially affected by land cover changes that vary among landowners? Scenarios of land cover change were projected by using a spatially explicit model in which the probability of land being converted from one cover type to another was conditional upon social, economic, and ecological factors. Potential habitat was defined for each species based on resource needs related to land cover and topography and was mapped at each time step. Spatial pattern of potential suitable habitat for each species was analyzed by computing area, number of patches, mean patch size, and area of the largest patch of suitable habitat. Simulations extended for 100 yr with a 5-yr time step. The different scenarios, based on historical periods and management options regulating forest loss, produced qualitatively different landscapes. Restrictions on forest harvest produced more, better-connected habitat for forest species. However, habitat changes for species were only partially predicted by changes in land cover types. For example, a 5–10% decrease in the amount of grassy or brushy cover in the HORB resulted in a 10–20% reduction in habitat for honeysuckle. When responses of all species were considered collectively, there were effects of both private and public ownerships in the LTRB but no interaction between the two ownership types. In the HORB, variation in the rates of land cover change for public lands had the greatest effect on species habitats. Our results suggest that both landscape-level approaches, which provide a means to quantify and monitor broad-scale changes related to biodiversity and ecosystem processes, and species-level approaches, which provide an appropriate context for interpreting the significance of landscape-level changes, are useful for effective conservation.