Nikhil R Chari Rose Hills
Competition Between Soil Methanogenesis and Iron Reduction Under Discrete Temperature and Redox Conditions
This research project will investigate the effects of redox conditions on temperature sensitivity of soil methane (CH4) and carbon dioxide (CO2) respiration. Temperature and rainfall regimes are changing with climate change, which can create fluctuating redox dynamics in humid environments such as tropical forests and wetlands. This has global implications for ecosystem carbon (C) storage and loss. CH4 is a potent greenhouse gas produced under anaerobic conditions, and the effects of changes in temperature on redox and CH4 fluxes are not well understood. Fe-reducing microorganisms can contribute significantly to CO2 production under anoxic conditions, as they operate anaerobically in redox oscillating environments, but also competitively suppress methanogenic microbial access to soil acetate, an important soil C source for CH4 respiration. Fe pools and CH4 and CO2 fluxes will be measured in a humid tropical forest soil and a temperate wetland soil. Both contain Fe-reducing microbes that likely play a critical role in regulating CO2 and CH4 fluxes under anoxic conditions. This study will offer insight into the effects of temperature on the temporal sequence of Fe reduction and methanogenesis in different redox environments.