Holocene ecohydrological dynamics and related carbon balance in the oligotrophic peatlands of north-central Québec, Canada

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In the central-north Quebec region, peatlands are vulnerable to recent climate change but also to industrial development activities. Peatlands in this region are mainly represented by systems that developed in topographic depressions of the Precambrian Shield. They are characterized with surface patterning similar to that observed in western Labrador, central Sweden and northern Finland. In eastern Canada, those ecosystems have shown recent ecohydrologic disequilibrium expressed by a general water table rise. In this region of Quebec where mining activities are in development, peatlands had never been studied in detail before a successful NSERC Engage project and a Mitacs Acceleration project were initiated during summer 2016 in collaboration with the industrial partner Stornoway Diamonds Corporation (Mine Renard). Preliminary results show that the peatlands do present a similar pattern of ecohydrological disequilibrium to those documented in the northeast section of the La Grande River watershed and confirm the importance of investigating their vulnerability to natural and anthropogenic pressures in terms of hydrology but also in terms of future greenhouse gas (mainly carbon dioxyde and methane) balance. The proposed project aims at quantifying the hydroclimatic changes that may have influenced the ecohydrologic disequilibrium phenomenon in these northern ecosystems. To do so, quantitative paleoclimate reconstruction using pollen, plant macrofossils and water table reconstructions will be developed to support modeling peatlands water dynamics (including groundwater exchanges) in order to identify the most sensitive parameters that influenced the phenomenon in northeastern Canada over the past millenia. Both Stornoway Diamonds Corporation and Nemaska Lithium industrial partners support this initiative as wetlands compensation measure required from the Quebec government. One of the expected results transferred to the industry will be the development of an index of biological integrity for vulnerable peatland systems in the context of the ongoing development on the northern territory.