Seminar: Dr, Suzanna Brauer, App State

UNC Marine Sciences’ Associate Professor Marc Alperin hosts a seminar presented by Suzanna Brauer, Ph.D.

Seminar Title: Flipping the switch: Peatland warming triggers accelerated carbon degradation, altered methane dynamics, and reverse ecological succession

Presenter Affiliation: Appalachian State University

Summary: Peatlands harbor unique microorganisms that demonstrate adaptations to stressful conditions, including low nutrient concentrations, high proton concentrations (resulting in low pH) and relatively low concentrations of sodium, potassium and other ions necessary for life. Peatlands are currently net carbon sinks and are estimated to store 1/3 of the total terrestrial carbon. Climate models indicate that the last glacial maximum was 3-5°C cooler than the present. This warming appears to have caused southern Appalachian peatlands to shift from C-accumulating bogs to net C releasing fens since the last glaciation, resulting in sparse, oligotrophic to minerotrophic fens that are older, more highly decomposed and much more highly fragmented than their northern counterparts. These southern peatlands may serve as a proxy for what will happen with northern peatlands as the mean annual air temperature in the southern portion of Canada is predicted by climate models to increase 3-4°C by 2020 and 5-10°C by 2050. Laboratory experiments on a proposed novel order of alphaproteobacteria, the Micropepsales, as well as genome data from peatland methanogens indicates that these fragile ecosystems, and the organisms harbored within, risk extinction with increased warming. Microbes in peatlands that are experiencing warming shift the hydrolytic and fermentation balance from incomplete decomposition to more complete decomposition, resulting in a shift from H₂/CO₂– and toward acetate-fueled methanogenesis. Initial results from our research efforts in conjunction with the Department of Energy’s Global Peatland Microbiome Project have shown distinct differences in microbial communities from peatlands that have greater accumulation of carbon (bogs) to those that have greater decomposition (fens). Similar to the ‘canary in a coal mine,’ we hypothesize that there is a specific type or suite of genes that may become activated when peatlands convert from carbon-accumulating to carbon-releasing. This “molecular switch” allows the organic matter in peatlands to decompose more completely and shifts the microbial metabolic products away from H₂/CO₂ and toward acetate. Thus, we propose that that a new factor representing microbial decomposition pathways (Microbial Gene Types) should be a key input that will strengthen the predictive power of global climate and land models such as the CLM4.5 model.