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• E. Mosbacher *
  Department of Biology, Clarion University of Pennsylvania
• C. Williams *
  Department of Biology, Clarion University of Pennsylvania

Abstract

Decades of chronic browsing by overabundant white-tailed deer (Odocoileus virginianus Zimmerman) has strongly influenced forest pattern and process on the Allegheny High Plateau Ecoregion of northwestern Pennsylvania, USA. Previous research has found that riparian forests contain the greatest herbaceous plant species richness of regional plant communities but little is known about the impacts of deer browsing on the structure and composition of the herbaceous layer (all vascular plants < 1 m tall) of Allegheny High Plateau riparian forests. We examined browse preference and browsing intensity by white-tailed deer on the herbaceous layer of five riparian forest study sites in the Allegheny National Forest during the summer growing season (July, September). Browsing intensity was low to moderate and differed significantly among sites and sample periods. Deer selectively foraged on a few preferred plant species during certain sampling periods, particularly Aster divaricatus, A. prenanthoides, Chelone glabra, Impatiens capensis, Pilea pumila, Polygonum virginianum and Ranunculus hispidis. We found that plant species richness and composition, and browsing intensity by white-tailed deer, are highly variable across riparian forests of the region. In order to assess or predict deer browsing impacts to regional riparian forests, we suggest that riparian sites be studied individually, perhaps on a watershed basis, as the surrounding landscape and available habitat may influence deer densities and foraging activity in an individualistic manner.