Carbon dynamics in coastal peatlands of Quebec's North Shore

Northern peatlands cover only 3% of the earth's surface but store approximately 33% of the terrestrial soil carbon. These ecosystems absorb carbon dioxide (CO₂) through surface vegetation photosynthesis and release C through plant respiration (CO₂), peat decomposition (CO₂ and methane (CH₄)) and the export of dissolved organic carbon (DOC). Despite their extensive coverage, coastal peatlands on Quebec's North Shore region (Eastern Canada) have been poorly documented to date. Although mean annual temperature and total precipitation do not vary significantly along the North Shore coast, peatland surface morphology, vegetation and long-term C accumulation rates differ through this region. The peatlands in the Baie Comeau area are dominated by sphagnum spp. and peat accumulation can reach 5m, while peatlands of the Havre Saint-Pierre region are dominated by Lichen and peat accumulation reaches approximately 2m. Furthermore, while all peatlands in this region are characterized by the presence of pools typical of boreal peatlands, they differ in their relative size and potential contribution to C exchange. It is hypothesized that presence of permafrost during the Little Ice Age in the Havre Saint-Pierre region could have influenced these differences. However, the effect on the contemporary C exchange rates remains to be documented. The objectives of this research are to: 1) examine the contemporary C exchange rates from two coastal peatlands in the Baie Comeau and Havre St-Pierre region given the differences between the two regions and the potential permafrost history in Havre St-Pierre; and 2) evaluate the contribution of pool fluxes to the ecosystem level peatland C budget. This poster will present results of growing season CO₂-net ecosystem exchange and CH₄ fluxes measured using eddy covariance and static chamber method over a mosaic of microforms in two coastal peatlands.