DISSERTATION RESEARCH: Microbial Oxidation of Methane in Anaerobic Soils: Ecological Significance in Mitigating Terrestrial Methane Flux

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Microorganisms that consume methane can play an important role in controlling global climate since each molecule of methane is about 26 times more effective than carbon dioxide in the greenhouse effect. Although many studies have investigated soil methane consumption, they have focused on methane consumption in the presence of oxygen, overlooking the potentially important role of anaerobic methane consumption (anaerobic oxidation of methane; AOM). Humid tropical forests are globally significant sources of atmospheric methane, accounting for more than 17% of all methane emissions. Boreal and arctic wet soils also release significant quantities of methane to the atmosphere, producing over 10% of all methane emissions. It is important to identify and characterize processes and organisms that help to control methane fluxes from these biomes. Anaerobic oxidation of methane is a potentially important process not previously identified in tropical or boreal terrestrial systems. Preliminary work demonstrates that AOM does occur in both tropical and boreal soils. This dissertation project investigates AOM in soils from Luquillo Experimental Forest (Puerto Rico) and Bonanza Creek LTER (Alaska) as tropical and boreal model ecosystems. Microogranisms and their methane oxidizing activities will be analyzed using molecular and genomic techniques in combination with geochemical analyses. The proposed research will advance our understanding of the microbial basis and distribution of anaerobic methane oxidation, and determine whether this soil process important in climate forcing. This knowledge will help us understand the possible impacts of land use change on the consumption of methane by soils. To help introduce young scientists to ecological research, undergraduate students will be involved in the project through the SPUR (Sponsored Projects for Undergraduate Research) program sponsored by the College of Natural Resources at UC Berkeley. Upon completion of this project, results will be published in peer-reviewed international journals and presented at international scientific conferences.