Interisland Variability of Dune Plant Community Structure

INTERISLAND VARIABILITY OF DUNE PLANT COMMUNITY STRUCTURE ON VIRGINIA’S BARRIER ISLANDS Justin K. Shafer Old Dominion University, 2010 Director: Dr. Frank P. Day The barrier islands of the Virginia Coast Reserve LTER site provide an opportunity to study interisland variability of dune plant communities. My research focused on the variation in biomass and diversity of communities among islands and dune positions. Grassy dunes of young, intermediate and old age were sampled on Smith, Hog, and Parramore Islands. Aboveground biomass was obtained from harvest plots, and roots were extracted from cores. Data were collected on depth to groundwater and total soil nitrogen. Variation in mean aboveground biomass was evident among the islands with the highest values on Hog Island, followed by Smith, then Parramore Island. Results for belowground biomass were similar, except the highest values were on Smith Island and then Parramore Island. Aboveground biomass was greatest on intermediate dunes, followed by the older dunes. The young dunes, frequently disturbed by overwash, had the least. Patterns in belowground biomass were variable among the different age dunes, with significant differences on Smith Island. In general, the oldest dunes had the highest biomass and the youngest the least. Species richness ranged from 40 species on Smith Island to 33 species on Parramore. Among dunes, results varied from an average of 17 species on the older dunes to 10 species on the youngest. The oldest dunes had the