Paleoclimates and ecosystem dynamics in the Hudson Bay lowlands

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The extensive peat-forming wetlands of northern Canada are an important repository of biodiversity, and are a globally significant carbon pool. Evidence from biogeochemical and paleoenvironmental studies indicates that peatland dynamics affect atmospheric greenhouse gases, and thus, the climate system. Because of the importance of peatlands to the global carbon cycle and the climate, more information is needed on the sensitivity of these systems to climate or hydrological changes. For example, it is critical to know what magnitude of change in water table position or air temperature is necessary to produce a shift in the carbon balance of a wetland from sink to source. The paleoecological record provides information on past changes in wetland systems, which can be applied to understanding contemporary or future changes. This proposal involves the analysis of peat and lake sediment cores from the Hudson Bay Lowland, Canada's largest but most poorly studied wetland. These cores will be used to determine how post-glacial uplift, plant succession, fire and climate interact to produce changes in wetland plant communities. Lake sediment cores will be used to produce quantitative climate reconstructions, based on assemblages of fossil pollen grains and other biological indicators. These proxy-based reconstructions will then be linked to models of carbon accumulation both at local and regional scales, and will be integrated into syntheses of wetland dynamics over the past several millennia at the global scale.