Term of Award

Spring 2007

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Department

Department of Biology

Committee Chair

Lissa M. Leege

Committee Member 1

C. Ray Chandler

Committee Member 2

Edward B. Mondor

Abstract

The effects of herbivores and invasive plants on native plants are well known, but few studies have addressed their impacts on rare plants. Threatened or endangered plant species may be more susceptible to negative effects of biotic factors due to their already low distributions. My study quantifies the interactions between deer, an invasive plant, a rare herb and its associated plant community to assist in the conservation of native plants. Trillium reliquum is an endangered spring ephemeral herb that is native to three states in the southeast. It is threatened by the encroachment of Japanese honeysuckle (Lonicera japonica) and white-tailed deer (Odocoileus virginianus) herbivory. I selected five sites in Georgia to examine the impacts of deer and honeysuckle on T. reliquum across its Georgia range. Four treatment combinations were established within each population, including: 1) deer excluded, honeysuckle present 2) deer excluded, honeysuckle removed 3) deer accessible, honeysuckle present 4) deer accessible, honeysuckle removed. I measured deer and honeysuckle impacts on T. reliquum and plant community structure in 2005 and 2006. Trillium reliquum was found in both species rich and species poor habitats. Deer and honeysuckle did not negatively impact species richness. Levels of deer browse intensity varied across sites and honeysuckle was the most frequent vine at most sites. White-tailed deer decreased fruit production and increased dormancy in T. 2 reliquum. Honeysuckle was associated with small but stable trillium populations. Empirical data and matrix models demonstrated that removal of honeysuckle results in significant population increases. This suggests that honeysuckle suppresses T. reliquum emergence. Conservation efforts for T. reliquum should focus on long-term deer population management and the control of invaders. Also, the conservation of subadult and reproductive individuals is important to T. reliquum population growth.

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