Recent carbon accumulation in boreal peatlands using Sphagnum δ13C composition and proxy indicators

Julie Loisel
Department of Geography,
University of Quebec in Montreal

Michelle Garneau
GEOTOP-UQAM-McGill and Department of Geography,
Université du Quebec a Montréal

Jean-François Hélie
GEOTOP-UQAM-McGill and Department of Earth Sciences,
Université du Québec à Montréal

Since organic material stored in ombrotrophic peatlands constitute a continuous high-resolution record of Holocene climatic changes, a combined analysis of proxy climate indicators that respond to different climate signals can potentially improve palaeoclimate reconstructions. To improve comprehension of the environmental factors that control recent organic carbon accumulation in boreal peatlands, we examined surface vegetation patterns, organic carbon isotopic composition and C/N ratio of four Sphagnum mosses species (S. fuscum, S. capillifolium, S. magellanicum and S. pulchrum), and testate amoebae relative abundance in two boreal peat bogs of the James Bay region, Northern Quebec.

In order to interpret these palaeoindicators as a record of environmental parameters, we attempted to calibrate Sphagnum-climate relationships by 24 sets of surface mosses species from dry hummocks, lawns and submerged hollows, since the hypothesis of a relationship between isotopic composition of the Sphagnum mosses and water table depth was suggested. A total of twelve cores (1m) were collected in the three biotopes previously mentionned. Recent chronology of peat accumulation was obtained by 210Pb and AMS radiocarbon dating. The carbon isotopic composition and C/N ratios were performed on bulk material of the Sphagnum species. 
 

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