The overall goals of process-level investigations of the sources and sinks of trace gases are to improve capabilities to: (1) determine both current and potential global contributions of biogeogenic versus anthropogenic sources, including possible feedbacks resulting from global change; and (2) evaluate the effects of various remediation options, including controls of emissions and land use mechanisms. The results of the research will be incorporated into mathematical models that can be used to predict the net fluxes of the gases as a function of various hypothesized land uses or climate scenarios. To accomplish these goals, process-level investigations in the laboratory and field will focus on developing fundamental functions that quantify the effects of changes in climate and stratospheric ozone on the biogeochemical dynamics of the gases.