Master of Science (MS)
Renewable Natural Resources
Colonization of natural areas by Chinese privet (Ligustrum sinense Lour.) threatens biodiversity and preservation of native habitat in the southeastern United States. High rates of seed production and dispersal, coupled with clonal growth, result in a competitive advantage when introduced to novel areas. Land managers have attempted to control L. sinense through prolonged flooding, prescribed fire, and herbicide application with little success. I determined presence of L. sinense invasion in four sites in Louisiana and assessed key reproductive, growth, and survivorship characteristics defining its life course. I used vegetation surveys, germination trials, dendrochronology, and demographic models to elucidate stages in L. sinense’s life cycle that contribute most to population growth. Populations of L. sinense have the potential for rapid growth. I germinated seeds under growth chamber, greenhouse, and field conditions. Stage-based matrix projection models showed the finite rate of population increase (λ) ranged from 1.48 in the field to 2.26 in the growth chamber. I used elasticity analysis to identify the proportional contribution of remaining in a stage (P), growing to a subsequent stage (G), and fecundity (F) to population growth, and perturbed matrices to mimic management strategies. A 50% reduction in PSEEDLING, PJUVENILE, and PSMALL ADULT reduced λ to 1.66 in the growth chamber and 1.63 in the greenhouse. Under field conditions, a 50% reduction in all Pi was required to bring λ to 1, so that populations were stationary. Reductions in FADULT did not immediately cause a decline in population growth. Approaches that target multiple life stages may be more successful for managing L. sinense. Using field germination rates, reduction of FLARGE ADULT by 50%, plus a 50% reduction of GSEEDLING and GJUVENILE, and PSMALL ADULT and PLARGE ADULT made population growth stationary (λ = 1.04). Management techniques that increase annual mortality of specific life stages may be more cost effective than targeting all individuals within a population. This study has identified transitions that contribute most to population growth over a range of growing conditions and indicated management options that may streamline control of this invasive plant.
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Klock, Metha Martine, "Using demographic models to manage Chinese privet (Ligustrum sinense Lour.)" (2009). LSU Master's Theses. 3117.