OPUS: MCS - Developing a mechanistic understanding of decomposition of organic matter in frozen soil

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During the winter season, soil microbes can remain active, even in frozen soils. It has been shown that soil microbes can continue to live and function over the winter. The activities of these microbes can be important for ecosystem carbon and nutrient cycling. But, it is not known exactly what microbes are doing in frozen soils over the winter. This project will advance understanding of winter processes by developing a model to understand microbial activity in frozen tundra soils. This project will also provide a mid-career scientist with an opportunity to gain new research capabilities in ecosystem modeling. The project builds on a rich history of field studies of carbon cycling in the Arctic. The project will have substantial educational impact, through integration with an undergraduate research program, thereby strengthening the scientific community.This project will explore the mechanisms that drive seasonal patterns of soil respiration. The central goal is to understand the response of winter respiration to changes in temperature and vegetation. The project will support development of a robust mechanistic model that incorporates cold season processes. The key is to link carbon and nutrient cycling in plants, soils, and microbes. The model will be based on an existing resource acquisition and allocation model. The new work will add new connections between substrate availability and freeze-thaw dynamics. The model will be developed for tundra ecosystems. But the results will be relevant to any seasonally-frozen ecosystem. This project will deepen understanding of ecosystem processes that may be seasonally disconnected but have strong plant-microbial linkages. This project will address fundamental questions in ecosystem ecology about resource acquisition, allocation, and nutrient cycling during the winter.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.