ABSTRACT PROPOSAL # : DEB-9708596 INVESTIGATOR(S) : MILCHUNAS INSTITUTION: COLORADO STATE UNIVERSITY Although the effects of increasing atmospheric CO2 concentrations on primary production and other aboveground ecosystem processes are widely studied in field experiments, experimental studies of the effects of CO2 belowground have generally not been done. The aims of this research are to investigate the effects of elevated CO2 concentrations on soil C dynamics and N cycling in Colorado grasslands. The main driver of belowground responses is assumed to be CO2-induced changes in plant C an N allocation among soluble exudates versus tissue components, in addition to changes in total C and N fluxes. The focus of the measurements is on root exudates, plant litter chemistry and litter decomposition, and changes in soil fauna, particularly nematodes. Results will be synthesized using the Century simulation model. This research is part of the NSF Environmental Geochemistry and Biogeochemistry Program, with support from the Divisions of Environmental Biology, Earth Sciences, and Atmospheric Sciences.
