Global change impacts on C storage and N cycling

A major focus of my research is to understand not only how the relationship between plant and microbial communities vary among ecosystems, but also to understand how these relationships are altered by global change. Specifically, my research has focused on how increased elevated atmospheric O3 and CO2 affect plant-microbe interactions. The significance of global change for biogeochemical cycling is well recognized at broad scales, but the microbial mechanisms that regulate ecosystem responses to global change are not well understood. Integrating microorganisms into our understanding of ecosystem ecology is a critical next step for accurately predicting ecosystem responses to global change and appropriately managing terrestrial ecosystems. Climate change affects the composition and function of microbial communities indirectly through alterations in plant community composition or the physical environment. It is also possible that climate change can have a direct effect on the physiology of some microorganisms. Changes in the composition and function of soil microbial communities, in turn, affect the biogeochemical cycling of elements, resulting in positive and negative feedbacks to aboveground communities as well as C storage and trace gas fluxes. Ongoing research at the Duke and Rhinelander Free Air CO2 enrichment sites investigates how soil C and N cycling is altered by global change. This research examines how microbial metabolism and soil C sequestration is affected by elevated atmospheric CO2. A second branch of this research aims to understand how chitin-degrading microorganisms are affected by elevated atmospheric CO2 and O3 and the implications this has for N cycling.