DISSERTATION RESEARCH: Landscape Patterns in the Biodegradability of DOC and DON Within and Among Arctic Hillslopes

Dissolved organic matter is an important source of energy and nutrients for plants and microorganisms found in tundra soils and streams. As the arctic climate warms, the fate of carbon currently stored in very cold or frozen soils will be controlled by the balance of microbial mineralization (release of carbon to the atmosphere) and plant productivity (storage of carbon in plants and soils), both of which are influenced by the availability of dissolved organic matter. Two major controls on dissolved organic matter transport are the ability of microbes to decompose specific dissolved organic compounds (biodegradability), and stabilization of dissolved organic matter by soil particles. However, landscape patterns in biodegradability and stabilization of dissolved organic matter have not been well studied in high-latitude watersheds. Related dissertation research has focused on the stabilization of dissolved organic matter by mineral soil components in arctic watersheds. The research proposed in this project will examine spatial patterns of dissolved organic matter biodegradability by characterizing the chemical composition of dissolved organic matter (an important control on biodegradability), and determining rates of microbial dissolved organic matter decomposition within and among hillslopes in arctic Alaska. In addition to inclusion in publications, the results will be disseminated through the Arctic Long Term Ecological Research database. This study will increase our understanding of how carbon and nutrients move in the tundra, especially in view of changes expected from regional climate warming.