Peat carbon in the Earth system through time

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Canada is home to a large portion of the world's wetlands. These ecosystems have accumulated vast pools of carbon in the form of peat over the Holocene and Pleistocene Epochs, and have also been important natural sources of methane, a potent greenhouse gas, for many thousands of years. Thus, Canada's wetlands affect the global carbon cycle in complex ways, and this is predicted to change with climate warming. The overarching goal of my research program is to investigate the role of peat-forming wetlands in the global carbon-climate system, thus providing Canada with critical new information to face the challenge of mitigating present and future climate change. The proposed research program addresses a series of open questions in wetland paleo-biogeoscience. The first concerns the size and importance of the temperate zone wetland carbon pool. Peatlands in high latitude and tropical regions are the largest in terms of overall carbon storage and are relatively well quantified. Temperate zone wetlands have been severely degraded by human impact, with massive losses in areal extent as wetlands have been converted to agricultural, urban or industrial land uses. Thus, this research will use cutting edge modelling techniques to predict where paleo-wetlands would have existed in temperate zone regions prior to human impact. Using available and new field data from remnant wetlands in anthropogenic landscapes, estimates for peat depth and carbon content will be combined with modelled areal extents to produce the first estimates of the size of the temperate wetland carbon pool. The second objective relates to the quantification of peat carbon in “buried” pools. While glacial erosion has prevented the persistence of widespread peat carbon from ancient peatlands dating to the Pleistocene, there are locations in Ontario's Far North where peatlands >30,000 years old are preserved underneath glacial deposits, owing to unique geographic settings. Using dating techniques, and the study of macro- and micro-fossil indicators, this research program seeks to determine how and why peat carbon accumulated at those times. Finally, this program seeks to investigate net carbon balance over the post-glacial period in peatlands of Ontario's Ring of Fire and adjacent Hudson Bay Lowlands. Peat cores will be collected from these regions for analysis of testate amoebae (micro-organisms sensitive to water table depth) and novel molecular indicators which will be integrated to determine rates of carbon uptake and release over time in response to shifting climates and ecological succession. These are regions with extensive peatlands which may be subject to future development. Through a series of projects to be carried out by student trainees, this research will provide critical information for determining the importance of our wetlands in global carbon cycling and in the climate system.