The Alteration of Soil Chemistry through Shell Deposition on a Georgia (U.S.A.) Barrier Island

Abstract

St. Catherines Island, located off the coast of Georgia (United States), has been inhabited by humans for close to 5000 years. The island's long-term habitation and varied history of land use has left a legacy of anthropogenic impacts that has strongly influenced the composition and function of the current vegetation communities and underlying soils. In this study, we examined the chemistry of surface soils collected from 32 sites representing five historical land uses (old cotton plantations, longleaf pine savanna, hickory forest, maritime forests, and shell middens) to determine how human activities have affected the island's surface soils. We found that shell deposition left a strong chemical signal, significantly increasing soil pH, cation exchange capacity, and concentrations of Ca, total nitrogen, and several micronutrients. Soils under the hickory-dominated forest had chemical characteristics that were intermediate between the middens and the other three cover types. Despite a wide range in pH, all sites had very high concentrations of extractable P, possibly because of retention by Ca and Fe. Shell deposition has altered soil chemistry in numerous areas across the island, and this has important implications for soils and the resultant vegetation patterns currently seen along St. Catherine's coastlines as well as other coastlines throughout the world.