9623094 Firestone Microbial taxonomic and functional diversity may have the potential to determine the rate and dominance of different carbon stabilization pathways. In this research the PI's propose to achieve three objectives, each addressing the central question: do microbial communities vary in their ability to determine the fate of carbon in soil? To accomplish these goals, the PI's will assess microbial functional and taxonomic diversity, investigate community control over carbon partitioning, and will quantify the contribution of microbial cell walls to stable carbon. The PI's hope to involve aspects of humus chemistry, soil microbiology and ecosystem ecology in advancing our understanding of the role that microorganisms and microbial diversity play in ecosystem functioning. Ultimately, this work may have implications for regional carbon cycle models, and for predicting response of soil carbon pools to environmental and land-use change. ??