E-mail : simon.thibault@roche.ca

Recent dynamics of ombrotrophic permafrost peatlands at their northern limit of distribution
 
Supervisor : Serge Payette

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Ombrotrophic peatlands are, with a few exceptions, the only ecosystems in the James Bay region that contain permafrost. The two most important factors that influence the dynamics of these permafrost peatlands are precipitation, which affects the vegetation cover that insulates the frozen peat, and fire. The primary objective of this study is to describe the recent dynamics of permafrost in the ombrotrophic peatlands of the region as well as to determine the principal factors that affect them. We hypothesize that the formation and degradation of permafrost is closely linked to recent climate change, particularly an increase in precipitation. The fieldwork for this project includes quantifying the presence and degree of permafrost degradation over the last 50 years by comparing the area and distribution of periglacial forms identified on aerial photographs taken in 1957 with those surveyed in 2004. In addition, an ecological inventory was conducted in order to evaluate the distribution of different vegetation species, the presence and expanse of permafrost, the surface topography, and the thickness of the peat. A post-fire chronosequence was also described at different sites in order to evaluate the impact of fire. The data was then compared with the recent climatic data (temperature and precipitation) of the region. Finally, an aerial inventory covering the zone between 52° and 55° N was carried out in order to establish the southern limit of permafrost peatland distribution.

Publication

Thibault, S. & S. Payette (2009). Recent permafrost degradation in bogs of the James Bay area, northern Quebec, Canada. Permafrost and Periglacial Processes, 20: 383-389.