Beaver (Castor canadensis) Impacts on Herbaceous and Woody Vegetation in Southeastern Georgia

Abstract

North American beavers alter habitat properties such as stream flow, faunal composition and plant community structure. In North America, the majority of studies on impacts by beavers have occurred in the northeast or western regions. This study examined the effect of wood-cutting and foraging by beaver on the surrounding plant community in Southeastern Georgia. To determine their impact, beaver modified habitat and nearby, but non-impacted riparian habitat, were sampled in a matched pair design. Vegetation surveys were performed, and species richness, density, relative abundance and canopy cover were calculated for every site. Richness of herbaceous vegetation was higher at distances closer to shore while richness of large woody vegetation increased with distance from shore with no difference found between beaver and control sites. The composition of herbaceous or woody vegetation did not differ significantly between beaver and control sites; species had an equal chance of occurring in either site. Canopy cover was similar at the two site types. Non-native species were rare and did not differ by site type. Beavers were in low density and had a relatively benign impact on the plant community. Density of woody plants was higher at beaver sites, suggesting that beavers may favor areas of abundant woody vegetation. Beaver impact may be less in southern regions than in northern ones. This may reflect the lower density of beavers, but impact also could be due to the year round availability of and access to vegetation.