Dissertation Research: Is organic matter chemistry or temperature a stronger driver of microbial community structure in permafrost soil?

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On earth, carbon cycles through many reservoirs including the atmosphere, plants, soils, rivers, and the ocean. Permafrost (permanently frozen soil) contains almost as much carbon as is stored in plant biomass globally, and is therefore an important carbon reservoir. Climate warming in the Arctic has caused degradation and thaw of permafrost in some locations. The carbon in permafrost is stored in the form of organic materials that are less decomposed than in soils from warmer climates, because decomposition has been stalled under frozen conditions. If these soils thaw, this carbon may be decomposed by microorganisms and released to the atmosphere during their respiration. This would add much more carbon dioxide, as well as methane, to the atmosphere and lead to a positive feedback, where increased carbon concentrations in the air cause increased warming, which causes the release of more permafrost carbon into the atmosphere. The amount of carbon dioxide and methane that is released to the atmosphere upon permafrost thaw will be a function, in part, of which particular microbial species are present. Metabolic patterns vary among the microbes, and as a consequence so do the quantities and composition of the possible respiratory products, mainly carbon dioxide and methane. Thus, it is important to study the occurance of various microbes and their functioning so that we can predict how they may respond to permafrost thaw. This project will examine how the species of microbes in permafrost are assembled. This has not been studied in the past because these soils are often deep and of course hard, making them difficult to penetrate and sample. Also, recent advances in DNA sequencing methods now allow researchers to ask new questions that were not possible even a few years ago. The results from this project will advance understanding of how changes in the temperature of permafrost soils affects microbes and the carbon cycle. Undergraduate students will participate in the project and be mentored in research skills and laboratory practices. Finally, the results will be made available through publications and more directly to a public audience on the web and in through live presentations.