Dissertation Research: Disentangling temperature controls on turnover of old, nitrogen-rich soil organic matter

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Soil organic matter is the largest land reservoir of carbon and nitrogen, the two major building blocks of all life on earth. Warmer temperatures may accelerate the breakdown of soil organic matter by microorganisms, causing major shifts in the dynamics of carbon and nitrogen. Among other impacts, the transformation of soil organic carbon into carbon dioxide in the atmosphere could intensify climate change. But warming will accelerate soil organic matter breakdown only if microbes have access to it. Stabilization of organic matter in soils by minerals is the dominant control on the availability of soil organic matter to microbes and so is the key to understanding how soil carbon and nitrogen will respond to warming. The approach proposed here uses a simple, realistic soil incubation experiment involving plant material labeled with isotopes to reveal the effects of warming. This experiment improves upon previous work by enabling tight control over carbon inputs and other driving variables (temperature, moisture, etc.), while using real plant material and soils. The results will improve our ability to predict future climate change and advance our understanding of the global carbon and nitrogen cycles. Throughout this study, the results will be disseminated through the mentoring of undergraduate students and presentations made at scientific meetings. The investigators will work with the Academic Advancement Center at Colorado State University, to recruit a low-income, first-generation and disabled student into a new program for undergraduate research. This student will take part in a series of workshops designed to improve scientific literacy and critical thinking and will be involved in every aspect of this project. At the culmination of this work, results will be presented at the 6th International Workshop on Soil and Sedimentary Organic Matter Stabilization and Destabilization and at the Colorado Front Range Student Ecology Symposium. By attending meetings designed for different audiences, the results will be made broadly available and integrated into research in multiple fields.