Microbial Modulators of Soil Carbon Turnover: from Genes to Ecosystems

Microbial communities play a vital and indisputable role in soil carbon (C) cycling, but microbial control over processes that facilitate soil C dynamics remains debated. Numerous basic questions remain to be addressed to understand microbial control over C cycling in terrestrial ecosystems that range from unraveling genome-based microbial ecophysiology to incorporating microbial mechanistic behaviors (cellular, community, and ecosystems) to predictive models. Empirical evidence of microbial regulation of soil C cycling is lacking that limits the coupling between microbial community functional traits, the environmental context, and the ecosystem processes. Because of the lack of this evidence, it is generally assumed that the link between community composition and the functional and metabolic responses is indirect. This is a significant constraint in developing a framework to incorporate microbial data into earth ecosystem models directly. In my presentation, I will discuss various case studies that incorporate bottom-up (genes-genome-ecosystem based approaches) analysis to address questions regarding regulatory and metabolic networks of microbes involved in C turnover at the community, aggregate, plot, and continental scales. These case studies will provide a mechanistic understanding of the role microbes play in C turnover and propose pathways to include these data to modify existing ecological models. Furthermore, I will present results from a long-term soil warming experiment that demonstrates the tight coupling of microbial responses with ecosystem-level processes changes. A comprehensive understanding of terrestrial microbial communities and specific processes that determine C dynamics' rate and fate will increase the likelihood of successful manipulation of the terrestrial ecosystem for increasing stable C inventories.