ADVANCE Fellows Award: A Mechanistic Understanding of the Responses of Soil Carbon Pools in Tropical Forests to Increasing Global Temperatures

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AbstractA grant has been awarded under the direction of Dr. J. Powers to investigate the mechanisms that determine the responses of soil carbon (soil C) pools in tropical forests to climate warming. Soils contain nearly three fourths of the world's terrestrial organic carbon, 28% of which is stored in tropical forest soils. There is currently much uncertainty and debate surrounding the potential responses of this large carbon pool to increasing global temperatures. Scientists are concerned that warmer climates may speed up the processes by which carbon is cycled through the soil, resulting in large releases of CO2 to the atmosphere and further accelerating global warming. The goal of this project is to better understand the short- and long-term responses of tropical soil C pools to increasing global temperatures. This project serves an important role in the career development of the principle investigator by allowing her to strengthen her skills as a scientist, establish an independent research program, and continue outreach with local grade school students, all of which facilitate her goal of obtaining a tenure-track position in academia.These studies provide an integrated set of laboratory experiments and modeling exercises to project potential responses of soil C pools from tropical forests to climate warming, and to evaluate the extent to which different mechanisms mediate these responses. Soils will be sampled from a worldwide network of 11 large forest inventory plots administered by the Center for Tropical Forest Science to take advantage of ongoing studies of forest dynamics, soil fertility and hydrology and to represent the diversity of conditions encompassed by tropical forests. The soils will be subjected laboratory conditions that simulate climate warming, and the following responses will be measured over the course of the incubations: CO2 efflux, microbial biomass, microbial community composition, and soil C pool sizes and structure. The laboratory results will be synthesized by using the data to parameterize a simulation model of soil C dynamics. The model will then be used to explore how large the potential fluxes of CO2 from the soil C pool to the atmosphere may be, given climate change. Together these studies will provide a benchmark for evaluating how the important C reserve stored in tropical forest soils may interact with the global climate system through CO2 emissions. These results will be of interest to a broad scientific community including tropical forest ecologists, soil and ecosystem scientists and global modelers. Moreover, these studies provide ample opportunities for training and education of grades 8-12 and undergraduates. In particular, the laboratory research will involve advanced high school students and undergraduates, and an ongoing science outreach program with eighth graders will be continued.