It has been well documented that deer browsing can alter forest community regeneration and composition by reducing the growth of or eliminating palatable plant species and simultaneously encouraging growth and facilitating the growth of more unpalatable or browse-resilient plant species. These shifts in community composition and structure have become a pertinent concern to forest managers, presenting a complex and pervasive issue. This becomes especially problematic in areas where the management objective is specific the maintenance of native plant communities. The degree of these composition shifts are dependent on deer numbers and available forage, which can vary greatly between throughout a region.
This study will be conducted in and around the Allegheny National Forest in northwestern Pennsylvania in partnership with the U.S. Forest Service. Vegetation surveys and deer density estimates will be conducted annually from 2013-2015. The goal of the project is to evaluate the effect ungulates have on habitat heterogeneity at differing spatial scales and vice versa, how the forest may influence deer densities and site selection.
We will couple forest community assessments and deer population data with spatial metrics to (1) explore how browsing co-varies with deer density and habitat heterogeneity over space and time. Simultaneously, we are placing replicated experimental sites throughout the region to explicitly test (2) how localized foraging impacts on vegetation vary across a range of deer densities and explore how habitat heterogeneity in the surrounding landscape mediate these impacts. Finally, there is an opportunity to use habitat selection and home range analyses to determine (3) if habitat heterogeneity and population density influence herd movement and browse site selection. The results will allow for the evaluation of whether ungulate densities are indicators of browse impacts and whether the impacts are co-varied with other spatial characteristics. The addition of deer spatial data will assist in the determination to whether habitat heterogeneity is a result of a top-down or bottom-up trophic process.
Principle investigator: Dave W. Kramer