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

入侵物种是人类引起的全球变化的重要组成部分。入侵植物可以改变本地植物群落的结构和组成，以及入侵生态系统的干扰机制。虽然已经研究了一些非土著植物入侵河岸带的生态效应，但对河岸带河流扰动机制与入侵这些生境的非土著植物之间的反馈作用知之甚少。本博士论文研究项目将探讨入侵女贞(女贞)对乔治亚州山前奥科尼河流域滩地森林结构和组成的影响，以及对滩地沉积速率的影响。这项研究将包括对中华绒毛虫传播和随后的地貌变化的景观尺度分析，以及对与入侵中华绒毛虫相关的改变的森林组成和结构、河流地貌和沉积速率变化的局部尺度调查。景观尺度分析将使用航空照片解译来确定中华绒毛虫入侵的时间及其传播率。此外，还将注意与中华绒毛虫入侵相关的河道形态的任何变化。当地尺度的分析将使用两个严重侵入区和一个L密度稀少地区的采样样带，以收集植被数据、土壤样本、地下水位深度测量以及计算年均泥沙淤积率所需的数据。将对不同地点的植被和环境数据进行比较，以确定与中华绒毛入侵成功相关的河流地貌和条件，并确定中华绒毛入侵是否与泛滥平原森林组成和结构的变化以及泛滥平原沉积速率的变化有关。该项目将提高对洪水状况和入侵植物引起的植被变化之间可能的反馈关系的一般理解；它将为了解未来几十年被中华绒毛虫入侵的山前洪泛区森林的命运提供洞察。作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立研究生涯。

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.