REU: Belowground Processes and Nitrogen Availability Across a Dynamic, Nutrient Poor, Barrier Island Landscape

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Past studies have suggested that nutrient>.>poor sites have greater nutrient immobilization in the litter, greater belowground allocation of biomass, and slower decay; all resulting in more conservative nutrient cycles. Most of these studies focused on forested ecosystems with minimal emphasis on belowground dynamics. The primary objectives of this new research project are (1) to quantify the relationships between C and N availability and belowground dynamics across a nutrient-poor, dynamic, barrier island landscape; (2) to quantify the influences of microtopography, successional age and microenvironmental interfaces (caused by fluctuating groundwater levels) on belowground processes; and (3) to refine and extend the application of newer techniques for belowground research. The research will be conducted along an established transect incommunities 65, 35, 25 and 5 years old on the accreting end of Hog Island on NSF's Virginia Coast Reserve Long-Term Ecological Research (LTER) site. Nitrogen amended and unamended plots will be used to test the effects of nitrogen availability on belowground processes. Root production, root decomposition, nitrogen immobilization rates in root litter, mineralization rates, and root and soil nitrogen content will be measured in the treatment and control plots. Reciprocal litter bag transplants will test the degree of control of root decomposition by external nitrogen supply versus litter quality. All processes will be evaluated in relation to microenvironmental conditions and successional age along the transect and vertically within the soil profile. The application of minirhizotrons in barrier island ecosystems will also be tested. Results from the project will be of fundamental importance to the basic ecological resolution of the governance of nutrient dynamics and plant community composition in nutrient-poor ecosystems. Additionally, the work should produce insights to assist in better management of barrier islands and beachfronts, areas where the interests of conservation, recreation and commercial development often collide. The principal investigator is well qualified, and institutional facilities are adequate to the task. Integration of this new project with the ongoing research program of the Virginia Coast Reserve LTER project will result in productive augmentation of both efforts.