Affiliation:
1. Department of Geography, Université du Québec à Montréal, Canada
2. Geotop Research Center and GRIL-UQAM, Université du Québec à Montréal, Canada
Abstract
Peatlands are natural ecosystems that provide archives of the hydrological cycle, ecological processes and terrestrial carbon dynamics. In the north-central region of Quebec (eastern Canada), patterned peatlands developed in topographic depressions of the Precambrian Shield following the Laurentide Ice Sheet retreat. These peatlands display characteristics similar to appa mires and other peatlands that developed at the ecotone between the open (taiga) and closed boreal forest biomes of the Northern Hemisphere, and also correspond to the biogeographic limit between ombrotrophic and minerotrophic peatlands. During the Neoglacial cooling period in northeastern Canada, patterned peatlands, mainly oligotrophic fens, registered a hydrological disequilibrium expressed by an increase in surface wetness as aquatic microforms expanded to the detriment of terrestrial surfaces. Ecohydrological trajectories were reconstructed from a detailed study of two patterned peatlands in order to document their sensitivity to climate variations. To do this, plant macrofossil and testate amoeba data were combined with peat carbon accumulation rates, C:N ratios, 210Pb and 14C chronologies. Data show that peatlands initiated ca 6500 cal. y BP as ombrotrophic or minerotrophic systems depending on site-specific conditions, followed by a general increase in surface wetness during the Neoglacial cooling until the end of the Little Ice Age. A relatively synchronous ecosystem state shift from oligotrophic to more ombrotrophic conditions was registered at the beginning of the 20th century in central and lateral cores of both study sites, evoking the likely influence of recent warming on peat accumulation. These results suggest a potential northward migration of the biogeographic limit of the ombrotrophic peatland distribution during the 20th century, which could have implications for the role of these ecosystems as C sinks at the continental scale. Overall, these peatlands have stored a mean carbon mass of ca 100 kg m− 2.
Funder
Mitacs Acceleration
Natural Sciences and Engineering Research Council of Canada
Northern Scientific Training Program
Stornoway Diamonds and Nemaska Lithium in partnership with NSERC
Subject
Paleontology,Earth-Surface Processes,Ecology,Archaeology,Global and Planetary Change
Cited by
20 articles.
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