Effect of Deer and Forest Edge on Understory Plant Communities

ABSTRACT White-tailed deer (Odocoileus virginianus) impact the ecological integrity of eastern deciduous forests by modifying plant community composition and structure. Previous studies have shown that overabundant deer can negatively impact the recruitment and persistence of both woody and herbaceous plants. However, the strength and nature of these interactions can depend on habitat context. Forest edges provide favorable habitat for deer along with many introduced plant species, and have the potential to modify the nature of deer impacts. Here, we explore whether forest edges shape the impacts of deer on plant communities within the forest landscape. Specifically, we excluded deer, or, alternatively, allowed deer access, in plots along the edge and within the interior of two northern hardwood forests. Background deer abundance in these forests was approximately 6–12 individuals per km2. After eight years of exclusion, we surveyed plant communities within plots to assess the impacts of deer on plant community composition across the forested landscape. We found that the impacts of deer were robust across habitat context within the forest, with relatively weak impacts on cover and richness of both native and introduced species. Edge habitat, on the other hand, had strong impacts on cover of both native and introduced species, as well as woody and herbaceous species, but the magnitude of these impacts was variable across the two forest sites. This work suggests that deer can have modest impacts when at relatively low densities, and that these effects can be consistent across forest habitat types, while forest fragmentation and subsequent generation of edge habitat can be an important driver of composition in the forest understory.