Permafrost and Peatland Evolution in the Northern Hudson Bay Lowland, Manitoba

• Published in: ARCTIC
• Main Authors: Dyke, Larry D., Sladen, Wendy E.
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Arctic Institute of North America 2010
• Subjects: fen; Hudson Bay lowland; lake; peat plateau; peatland; permafrost; polar bear; thawing; Wapusk National Park; tourbière basse; basses-terres de la baie d’Hudson; lac; plateau palsique; tourbière; pergélisol; ours polaire; décongélation; parc national Wapusk; Canada; Hudson; Hudson Bay; Arctic; Ice; Peat; Peat plateau; plateau*; Wapusk national park
• Online Access: https://journalhosting.ucalgary.ca/index.php/arctic/article/view/66383

The northern Hudson Bay lowland includes the largest area of frozen peat plateau bog in Canada. Polar bear denning habitat, caribou forage, carbon storage, and wetland drainage control provided by peat plateaus will be affected if post-Little Ice Age warming continues. Mapping and thermal modeling of frozen peat plateau stability indicate that permafrost peatlands are stable at a mean annual air temperature as warm as -3.5˚C. In the peat plateaus of the northern lowland, permafrost can be absent at the peat plateau margins where peat plateaus border fens or lakes. Here, insulating snow accumulations permit thawed conditions at mean annual air temperatures colder than -3.5˚C. Continued warming will result in expansion of thawed zones, subsidence at plateau margins, and even collapse of plateau surfaces, resulting in conversion to fen. This process has already occurred across north-central Manitoba, Saskatchewan, and Alberta since the end of the Little Ice Age, and there are signs that it is extending into the northern Hudson Bay lowland. Wave erosion of subsiding plateau borders at lake shorelines is also resulting in loss of peat plateau bog. Les basses-terres du nord de la baie d’Hudson comprennent la plus grande zone composée de tourbière oligotrophe de plateaux tourbeux du Canada. Advenant que le réchauffement du post-Petit Âge glaciaire se poursuive, l’habitat de tanières de l’ours polaire, les zones de fourrage du caribou, le stockage de carbone et la régulation du drainage des zones humides découlant de la présence de plateaux palsiques en subiront des conséquences. Le mappage et la modélisation thermique de la stabilité du plateau palsique gelé indiquent que les tourbières de pergélisol sont stables lorsque la température moyenne annuelle de l’air est aussi chaude que -3,5 ˚C. Dans les plateaux palsiques des basses-terres du Nord, le pergélisol peut être absent en marge des plateaux palsiques lorsque les plateaux palsiques bordent des tourbières basses ou des lacs. Ici, les accumulations de neige ...