Doctoral Dissertation Research: Biogeomorphic Effects of Ligustrum Sinense (Chinese Privet) Invasion on the Oconee River Floodplain in North Georgia

University Of Georgia Research Foundation Inc, Athens GA

Investigators

Abstract

Invasive species are an important component of human-induced global change. Invasive plants can alter both the structure and composition of native plant communities and the disturbance regimes of invaded ecosystems. Although some of the ecological effects of nonindigenous plants invading riparian zones have been studied, feedbacks between fluvial disturbance regimes in riparian zones and nonindigenous plants invading these habitats are poorly understood. This doctoral dissertation research project will investigate the effects of invasive Ligustrum sinense (Chinese privet) on floodplain forest structure and composition as well as on rates of floodplain sedimentation in the Oconee River watershed of the Georgia Piedmont. The study will include both a landscape-scale analysis of L. sinense spread and subsequent geomorphic changes and a local-scale investigation of altered forest composition and structure, fluvial landforms, and changes in sedimentation rates associated with invasive L. sinense. The landscape-scale analysis will use aerial photograph interpretation to determine the timing of L. sinense invasion and its rate of spread. Attention also will be given to any changes in stream channel morphology associated with L. sinense invasion. The local-scale analyses will use sampling transects in two heavily invaded areas and an area with sparse density of L sinense to collect vegetation data, soil samples, and depth-to-water-table measurements as well as needed data to calculate average annual rates of sediment accretion. Comparisons will be made of vegetation and environmental data among sites to identify fluvial landforms and conditions associated with successful L. sinense invasion and to determine whether L. sinense invasion has been associated with changes in the composition and structure of floodplain forests and changes in rates of floodplain sedimentation. This project will improve general understandings of possible feedback relationships between flood regimes and vegetation changes caused by invasive plants; and it will provide insights into the fate of Piedmont floodplain forests invaded by L. sinense in the coming decades. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.