Although deer were near extinction in Pennsylvania at the turn of the nineteenth to the twentieth century, the protections provided by the newly created Pennsylvania Game Commission and deer reintroductions quickly led to problems of overabundance.  Beginning in the 1940s, scientists at the USDA Forest Service Research Laboratory in northwestern Pennsylvania conducted a series of studies that documented the impacts of deer on forests and explored strategies to manage forests with high deer impact.  These studies ranged from long-term measurements of understory change in unmanaged old growth through exclosure and enclosure studies.  Each study provided evidence of deer impact on vegetation.  Taken together the studies show trends in long-term change that were not anticipated at the time of study design and implementation .  This paper will explore data from several studies to show the long-term changes in forest composition and structure – the legacy effects – of many decades of deer overabundance.

Results/Conclusions

Species that are unpreferred by deer increase in importance in both study plots and on the landscape.  Previous research has focused on the role of deer overabundance and other disturbances in increasing the proportion of understory herbaceous cover by hay-scented (Dennstaedtia punctilobula Michx.) and New York fern (Thelypteris noveboracensis L.)  This paper will also explore increases in the abundance of American beech (Fagus grandifolia Ehrh.), striped maple (Acer pensylvanicum L.), and black birch (Betula lenta L.).  The paper will also look at evidence from these studies that deer impact on forests is a joint function of deer density and landscape forage production.