Symposium no. 43 Paper no. 867 Presentation: oral 867-1
The Glacial Lake Agassiz basin in North-central Manitoba consists predominantly of glacio-lacustrine, clayey uplands and peat-filled lowlands. The region lies within the discontinuous permafrost zone. Permafrost mainly occurs in deep and shallow peatlands, and on uplands under mature closed black sp...
| Main Authors: | , , , |
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.5.2257 http://www.sfst.org/Proceedings/17WCSS_CD/papers/0867.pdf |
| Summary: | The Glacial Lake Agassiz basin in North-central Manitoba consists predominantly of glacio-lacustrine, clayey uplands and peat-filled lowlands. The region lies within the discontinuous permafrost zone. Permafrost mainly occurs in deep and shallow peatlands, and on uplands under mature closed black spruce-feather moss vegetation. Soil climate and permafrost characteristics along a toposequence, from upland to lowland, were monitored between 1981 and 2001. The study site, covering an area of 225 x 100 m, is under mature vegetation and is located in the northern part of the Boreal Ecozone, near Thompson, Manitoba. Monitoring instrumentation consisted of thermocouples/thermistors, wells, and frost tubes along a 225 long transect. Depth to permafrost was also monitored on a 25 m grid. Vegetation, drainage, and thickness of organic surface layers are the apparent dominant controls of soil climate and permafrost distribution. However, observed permafrost dynamics indicate that weather events, such as early fall or delayed snowfall, and wet or dry summers, also have a significant effect. Water movement during snowmelt occurs primarily over the frost table, and through the peat layer and the upper part of the mineral soil after heavy rains. Maturation of veneer bogs typically extends these shallow peatlands through the process of paludification, and the deepening of the peat generally leads to greater incidence of permafrost. However, if climate change results in more frequent wildfires or warmer summers, it is most likely that the expansion and extent of shallow peatlands and the distribution of permafrost will be reduced. |
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