Dr. Marcy Brown Marsden

Assistant Professor

Haggerty Science Bldg. 140
(972) 721-5245
mebrown@acad.udallas.edu

B.S., Biology, University of Dallas
Ph.D., Purdue University

The non-native shrub genus Ligustrum has been show to be an increasing problem in the forests of the southeastern United States. Invasion of Ligustrum has been facilitated through ornamental plantings of the shrub and establishment of Ligustrum stands as winter deer forage. Preliminary work on this species in the wooded property of the University of Dallas has shown nearly 60% reduction in number of native species when Ligustrum is present. This reduction in species threatens the diversity of Texas woodlands, and points to a need to understand Ligustrum establishment in a forest, and how it outcompetes adjacent native species and disperses to establish new stands.

The current research on Ligustrum focuses on several ecological levels, and the use of a combined observational and experimental approach. At the community level, we are studying Ligustrum invasions and how native plant populations are affected through diversity analysis and controlled removals of Ligustrum. At the population level, we are assessing demographic characteristics such as reproductive rates, rates of expansion and dispersal, and senescence. Identification of potential bird and mammal dispersers through trapping has been vital to understanding Ligustrum’s role as a food source. Finally, we are examining how each Ligustrum plant adapts to seasonal changes in its environment by altering its pattern of nutrient storage and photosynthesis. The newest work in the lab will incorporate biochemical study of Ligustrum, and in collaboration with the Ganter Lab will grow to include identification of cold-tolerance genes in this plant that may be important for overwinter survival.

In the four years of this study, 31 undergraduate research students have participated in the community ecology research program, and several have gone on to pursue graduate careers in the field of ecology and evolutionary biology. The research is well-suited for undergraduate students, as field studies require large numbers of individual field assistants. In this project students learn techniques for trapping and handling animals, mapping vegetation, and identifying plants. In the laboratory students learn to culture plants and assess nutrient reserves of plants. Ultimately, we hope this collaborative work will help to recognize the multiple ways in which a non-native species outcompetes native species, and identify mechanisms for minimizing the effects of non-native species.