DISSERTATION RESEARCH:Will CO2-mediated Increases in Fine-root Litter Progressively Decrease Forest N Availability by Increasing N Immobilization in Soil Organic Matter?

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Soils have the capacity to store carbon for a long time. The degree to which plant remains are protected from decomposition in the soil profile will determine the amount of carbon and nitrogen stored in soils in response to rising atmospheric concentrations of carbon dioxide. The objective of this research is to mechanistically link the decomposition of fine-root litter to carbon and nitrogen immobilization in soil organic matter. Fine roots and soil organic matter with a depleted carbon-13 isotope signature will be taken from a CO2-enrichment experiment in a deciduous forest stand and decomposed in a reciprocal transplant experiment. Carbon from the decomposing fine roots will be quantified as it is transferred to fractions of soil organic matter with different longevities. Results of this project will advance the understanding of terrestrial processes that regulate above- and belowground carbon storage in forested ecosystems, and inform models used to predict ecosystem responses to climatic change.