Temporal and spatial aspects of peatland initiation following deglaciation in North America |
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| Institution: | 1. Dept. of Geography and Environmental Management, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada;2. School of Geography and Earth Sciences, McMaster University, Hamilton, Ontario L8S 4L8, Canada;3. Dept. of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada;4. Dept. of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2R3, Canada;1. Department of Biogeography and Palaeoecology, Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, Dzięgielowa 27, PL–61 680 Poznań, Poland;2. Department of Geology, Babeş-Bolyai University, Kogălniceanu 1, 400084 Cluj-Napoca, Romania;3. Department of Geography, Northumbria University, Newcastle upon Tyne NE1 8ST, UK;4. Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung Senckenberganlange 25, D-60325 Frankfurt am Main, Germany |
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| Abstract: | A set of simple ecological models accounts well for the cumulative initiation of peatlands throughout North America in relation to glacial retreat. The most parsimonious form incorporates, first, a delay term to account for the lag during which newly deglaciated land became suitable for peatland initiation and, second, an intrinsic rate of initiation related to the probability of migration and establishment of plant propagules from elsewhere. The goodness of fit of the models, based on 1680 basal-peat dates throughout the continent, allows projection of past trends into the future. Factors contributing to the lag of about 4000 years between deglaciation and peatland initiation are suggested and data on colonization of deglaciated land by beavers (known to initiate peatlands) are presented. The rate of peatland initiation peaked between 7000 and 8000 years ago, but remains appreciable today. A marked depression of peatland initiation (8360–8040 BP) interrupted the peak rate. The time of the interruption matches the 8200 BP cold–dry event recorded in Greenland ice cores, and suggests that this event caused a substantial, continent-wide depression of an important ecosystem function, i.e., carbon sequestration from the atmosphere by peat deposition. Spontaneous initiation of new peatlands is projected to continue for millennia to come. |
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