Date of Graduation
Eberly College of Arts and Sciences
James B. McGraw.
American ginseng (Panax quinquefolius L.) is a long-lived understory herb considered rare within its range. Harvesting pressures and habitat degradation/destruction are thought to be the primary causes of population decline although others factors such as browsing by white-tailed deer (Odocoileus virginianus Zimm.) have not yet been explored. To understand the effects of deer browsing on natural ginseng populations, my research focused on four specific objectives. First, I investigated how plant characteristics and microsite conditions influence the susceptibility to being browsed. I found that apparency plays a role in influencing browse selection, such that large, reproductive plants in visible and accessible areas are more prone to browse than smaller, protected plants. The second study addressed the effects of deer browsing on individual plant growth, reproduction, and fate. Complete browsing terminated growth and reproduction in the season that it occurred. Carryover effects such as reductions in size-related measures, bud number, alteration of reproductive status, and reemergence were seen in the season following the browsing event. Consecutive years of browsing magnified these effects. The third study examined the role of deer as possible dispersers of ginseng seeds. The results of feeding trials using captive deer revealed that seeds are destroyed during the processes of mastication and digestion. Thus, deer are predators and not dispersers of ginseng seeds. Loss of seeds can negatively impact the seed bank and ultimately population growth and viability. The fourth study investigated the effects of deer browsing on population growth (lambda) using demographic matrix models. The general effect of deer browsing was a decline in lambda. These reductions in lambda are most likely due to selective browsing, carryover effects, and seed destruction. The overall conclusion from these studies is that overabundant white-tailed deer are negatively impacting natural ginseng populations. Due to current browse pressures, natural ginseng populations may be unable to support both deer and harvest. A plausible solution to this problem is the reduction of deer herds.
Furedi, Mary Ann, "Effects of herbivory by white -tailed deer (Odocoileus virginianus Zimm.) on the population ecology and conservation biology of American ginseng (Panax quinquefolius L.)" (2004). Graduate Theses, Dissertations, and Problem Reports. 2138.