White-tailed deer herbivory impacts on tree seedling and sapling abundance in the Lake States Region of the USA

Abstract

White-tailed deer (Odocoileus virginiana Zimmermann) browsing reduces seedling and sapling abundance of more palatable winter woody browse such as Tsuga canadensis L. Carrière, Thuja occidentalis L., Betula alleghaniensis Britton, and Pinus strobus L. across the Lake States Region of the USA. White-tailed deer consume buds and twigs of tree seedlings and saplings as forage. Deer populations in the Lake States Region of the USA have increased over recent decades due to a decrease in predators and an increase in habitat fragmentation. Higher deer population densities present challenges to regeneration of tree species. The objective of this work was to quantify the effects of deer browsing on tree seedling and sapling abundance and species richness of woody tree species which vary in deer browse palatability. Deer browsing impact measurements from the tree regeneration indicator from the US Department of Agriculture Forest Service’s Forest Inventory and Analysis program were used to predict seedling and sapling abundance from overstory basal area and a deer browsing index in the Lake States Region. Overstory basal area was important in predicting seedling and sapling abundance for all species (p < 0.05). Deer browsing affected seedling and sapling abundance differently across species, with the most palatable species showing lower stocking or negligible effects with browse. Results support the importance of quantifying impacts of deer browsing for use in determining the survival and abundance of palatable species in the smallest size cohorts.