Extent and Dispersal Rates of Chinese Privet ( Ligustrum sinense ) Invasion on the Upper Oconee River Floodplain, North Georgia

Abstract

Ligustrum sinense (Chinese privet, privet) is an invasive woody shrub with an extensive naturalized distribution in the eastern and southeastern United States. Although privet is considered an invasive species in many eastern states, to date there has been no attempt to quantify the areal extent of privet invasions in vulnerable ecosystems. In the Upper Oconee River Basin, northeastern Georgia, privet thickets are abundant on the river floodplain. At the landscape scale, I used historical aerial photographic analysis to determine the extent and timing of privet invasion along a 43 km reach of the Upper Oconee River I also used magnified historical aerial photograph images to investigate whether there are particular types of land uses associated with the invasion at three one-kilometer sub-reaches Privet was well established by 1951, the first aerial photographs of the area taken during winter leaf-off period, when 51% of 1,327 ha of floodplain surface had already been invaded. By 1999 privet had spread to 59% of the floodplain Analysis of the 43-km study reach, and qualitative observations of historical privet invasion at the three representative sub-reaches, suggest that the modest increases in privet extent over the study period are primarily due to invasion of agricultural fields and pastures. While some remnant patches of noninvaded floodplain forest persist in areas that experienced less human activity, most remaining stands of noninvaded floodplain forest are confined to backswamp areas where frequent flooding appears to exclude privet establishment and growth.