Dr. Correll, with Co-principal investigators Weller and Jordan, will measure in situ the gaseous nitrogen losses from a riparian forest that intercepts nitrogen for agricultural runoff. They will quantify the annual losses of gaseous N from the forest, investigate the environmental controls of denitrification, and assess the relative amounts of nitrogen lost as molecular nitrogen (N2) and nitrous oxide (N2O). The gaseous loss measurements will be combined with measurements of nitrogen transport in runoff and precipitation to yield a complete nitrogen input/output budget for the forest. They will also measure key parameters of the trees and soil top determine if a gradient of nitrogen availability exists within the forest and to evaluate the effects of the exogenous nitrogen storage and cycling and plant growth within the forest. They will construct a simulation model to summarize the resulting understanding of nitrogen transport and processing by the riparian forest. The results will address several issues of practical and scientific importance: the ability of riparian forests to buffer downstream systems from over enrichment from agricultural discharges; the release of N2O (which is involved in the "greenhouse" effect and stratospheric ozone depletion) from coupled cropland-forest systems; and the effects of chronic fertilization on deciduous forest systems. The study will also develop improved methods for field measurements of gas emissions from ecosystems, and produce basic information needed to manage nitrogen discharges from cropland-forest systems. Dr. Correll and his colleagues are leaders in the field of terrestrial-aquatic nutrient exchanges and riparian zone dynamics. Their research is developed from a strong conceptual foundation and utilizes new and innovative techniques to measure large scale gas emissions to the atmosphere. Their research is linked to other ongoing projects to allow extensive collaboration and exchange of information. Support for this research from the Smithsonian Institution and the Chesapeake Research Consortium is outstanding.
