The Biogeochemistry of Soil Nitrogen Cycling with Changing Precipitation Regimes
Current climate models predict that the Central Plains of North America will likely experience similar rainfall amounts with climate change, with longer dry periods and more intense events. Little is known about how these changes in precipitation patterns will influence soil microbial community structure or biogeochemical function. We are exploring these issues by performing reciprocal transplants of soil cores across the precipitation gradient of the Central Plains, and conducting laboratory experiments in which we manipulate moisture availability. Using qPCR, we are assessing changes in microbial community structure, and linking these changes to altered rates of nitrogen cycling and the extracellular enzyme activity responsible for the breakdown of soil organic matter. In collaboration with Dr. Nathaniel Ostrom at Michigan State University, we are exploring the use of 15N of N2O as a means of understanding the drivers of N2O production vs. reduction. In collaboration with Dr. Bryan Foster (KU Department of Ecology and Evolutionary Biology, KUERG) and Dr. Nate Brunsell (KU Department of Geography, KUERG), we are also manipulating soil moisture by altering timing of relative water limitation in grasslands of the KU Field Station. Here, we are examining extracellular enzyme activity and soil organic matter responses to varied water availability, and how these parameters relate to plant community structure and plot-level exchange of carbon and water with the atmosphere.
This material is based upon the work supported by the National Science Foundation under Grant No. 0910343.