Term of Award

Fall 2014

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Department

Department of Biology

Committee Chair

Subhrajit Saha

Committee Member 1

Lissa Leege

Committee Member 2

Ray Chandler

Abstract

Baptisia arachnifera (Hairy Rattleweed) is an endangered herbaceous legume that only occurs in Wayne and Brantley Counties of Georgia, United States. Many of the remaining populations exist in areas now managed for timber. This study investigated the effects of Imazapyr, an herbicide commonly used in timber management, on health and vitality of B. arachnifera under both field and greenhouse conditions. This study also analyzed leaf and soil samples from six populations of B. arachnifera to determine the nutrient content of the leaves. A recensus of a B. arachnifera population was also conducted in a site without commercial timber management. In the greenhouse, all B. arachnifera that were treated with herbicide died, regardless of herbicide application level. Control treatments did not die. Field results showed death of plants treated with low and high levels of herbicide dying before the control plants also died due to heat stress. The nutrients Al, B, Cu, Fe, Mn, Na and Zn were found in varying concentrations in leaf tissue between B. arachnifera population sites. A significant difference was found in calcium concentration in the soil between sites where B. arachnifera are present and absent. A higher percentage of sub-adult B. arachnifera were found in the 2013 census than the 2010 census of the site without commercial timber management. However, a higher percentage of seedlings, juveniles and reproductive B. arachnifera were found in the 2010 census. The finding of this study do not support the use of herbicide Imazapyr on sites with B. arachnifera. Future directions for research should include a closer look at how other competition controls such as burning and thinning affect each life stage of B. arachnifera, as well as studies on the overall health of each individual population of this endangered species on both managed and unmanaged timber land.

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