Decomposition will be studied in an emergent macrophyte.dominated habitat of the Okefenokee Swamp ecosystem in southeastern Georgia. In this detritus.based ecosystem, lignocellulose from the emergent Macrophyte Carex walteriana is the most abundant source of carbon. Since lignocellulose is largely indigestible to animals they cannot use its carbon (energy) until it is degraded by microorganisms. Thus, having an understanding of microbial transformations of lignocellulosic material and the factors controlling rates of its breakdown are key to understanding how the Okefenokee and other wetland ecosystems work. The research will be divided into three parts; detailed process studies, integrative system.level measurements, and modeling syntheses. The detailed process studies will focus on decomposition in field and laboratory efforts designed to clarify the temporal and spatial aspects of transformations, fate, and controls on decomposition not only of lignocellulosic, but also of non.lignocellulosic carbon. Techniques to be used in these studies include: the radiolabeling of substrates with .1.4C to determine the fate of the decomposed material; and the labeling of bacteria with ?.3H! thymidine to determine the efficiency of particle incorporation. The system.level measurements are designed to put the decomposition studies in context of the site's overall carbon budget. Standard methods including flow.through metabolic chambers and .1.4C "spiked" light.dark bottles will be used in the system level studies. Modeling will function as a synthesis tool in this research. Extant models of microbial degradation of lignocellulose will be expanded to: 1) consider spatial and temporal aspects of decay related to detrital inputs; and 2) incorporate more explicit and detailed controls on rates of decay including the influence of N, P and S. Finally, detailed flow and sensitivity analyses will be made of the modified models. The significance of this research is that it will help us to understand how wetlands, a major ecosystem type, worldwide, function. This research should provide a scientific basis for wise management of this important landform. Drs. Hodson, Wiegert and Hopkinson are very capable scientists with strong research records. The institutional support available to them is excellent.
