A comparative evaluation was performed using descriptors oflandscape and land cover patterns as to how they relate tovarying levels of anthropogenic disturbance and the structure ofbiotic communities. A spatial analysis program (a modifiedversion of SPAN) was used to compute measures of land coverdiversity, dominance, contagion, scaled dominance and contagion,fractal dimension of land cover patches, mean forest-wetlandpatch size, amount of forest edge, clustering of selected foresttypes, and the largest cover patches within two 100-km²watersheds of the Ridge and Valley province of centralPennsylvania. Landscape pattern analysis was conducted on asubwatershed basis, emphasizing different levels ofresidential-agricultural versus forest land cover, the majordifference between the two watersheds. Bird and vascular plantguilds were chosen to represent the overall biotic community. Thegeneral descriptors of diversity, contagion, mean forest-wetlandpatch size, proportion of forest cover, and the amount of forestedge were most effective in reflecting the disturbance levelswithin the watersheds and changes in guild composition for bothbirds and plants.