Term of Award

Spring 2010

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

Ray Chandler

Committee Member 2

Risa Cohen

Abstract

Trillium persistens, a federally endangered perennial herb, exists as fragmented populations in Georgia and South Carolina, U.S.A.I quantified the demography of T. persistens across its range and described its associated plant community, including a fire-dependent habitat. To examine the demography of T. persistens, one study site was established in each of four population fragments (Battle Creek, Moccasin Creek, Moody Creek, and Panther Creek) located in and around Tallulah Gorge State Park. At Moody Creek, T. persistens occurs in the threatened, fire-dependent Table Mountain pine ecosystem, dominated by Pinus pungens. To determine whether prescribed fire would impact T. persistens, 40 4-m2 plots containing T. persistens were established, with half receiving early-season prescribed fires in February, 2009. All four sites were censused over the 2009 and 2010 growing seasons to characterize T. persistens population dynamics and the composition of its associated plant community. I used these Census data to construct stage-based demographic matrix models to project population dynamics within each site over 25 years. Projections were determined using a low estimate and high estimate of fecundity. More individuals were found across sites in 2010 compared to 2009, but life stage structure did not differ between years. Fruit set was greater in 2010 compared to 2009 across sites. The associated plant community was variable among sites. Species richness differed significantly, ranging between 0.6-1.9, 0.65-1.8, and 4.2-6.35 species per site for herb, shrub, and tree, respectfully. Projections of T. persistens population size over 25 years based on the matrix models suggest overall decline of T. persistens across its range, with mean λ across sites ranging from 0.84-1.08. While the burn in 2009 did not show negative effects on T. persistens, land managers conducting prescribed burns in the future should use early-season cooler surface fires. Trillium persistens numbers should be monitored post-burn to see if they affect population sizes over time. Across sites, land managers should work to protect life stage transitions with the greatest impact on λ according to site, and monitor recruitment of new individuals.

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