Comprehensive Assessment of White-Tailed Deer Browse in the Presence of Beech Bark Disease at a Great Lakes National Park

Abstract

In northern hardwood forests, white-tailed deer (Odocoileus virginianus) impact both tree regeneration and groundlayer composition, leading to a dominance of American beech (Fagus grandifolia), an unpalatable species, as well as a reduction of preferred groundlayer species. Deer become especially problematic in areas with beech bark disease, such as at Sleeping Bear Dunes National Lakeshore. We analyzed datasets from Sleeping Bear Dunes, collected in 2009 and 2018, to assess vegetation change in three management units: a mainland unit with a long history of deer occupancy, and two islands, one with high deer pressure and one with no known history of permanent deer presence. For each unit, we tested for change in species richness and mean coefficient of conservatism. We also examined the groundlayer, testing for change in indices of abundance and size of preferred and avoided species. Finally, we compared regeneration of palatable and unpalatable tree species. We found increased nonnative species richness, decreased number and abundance of preferred herbaceous species, as well as decreased height of a preferred species. We also detected increased sapling density of beech while that of palatable species declined. Our data provide further evidence of the impacts of white-tailed deer on the forest understory. Management goals should focus on maintaining deer densities at or below 5 deer km–2 in order to promote growth of the full suite of herbaceous species typical of the region and habitat and to allow adequate regeneration of the overstory.