Effects of Human Disturbance on the Dune Vegetation of the Georgia Sea Islands

Abstract

This research investigates how human disturbance has affected foredune vegetation of the Georgia Sea Islands (GSI) in the United States. The cover of native dunebuilding grasses (Uniola paniculata L. and Panicum amarum Ell.) was more abundant within less-disturbed sites than in sites that had higher levels of human disturbance. In contrast, dunes in human-disturbed areas had significantly higher cover of alien plants and native generalist taxa, and they also had higher overall species diversity. Additionally, the cover of native dune-building grasses was significantly greater on protected National Wildlife Refuge islands than on more frequently visited and developed tourist islands. In addition to the ANOVA, nonmetric multidimensional scaling (NMS) analysis showed that the vegetation composition differed between disturbed and less-disturbed plots and between plots on tourist islands and protected islands. Both ANOVA and NMS analyzes agree that dunes in human-modified areas have lower dune-grass cover and greater cover of species that are not adapted to building and stabilizing dunes. Therefore, human disturbance may indirectly reduce dune stability by altering the dune vegetation.