CGRG Bibliography of Canadian Geomorphology
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Author : Beilman, D.W.; and Vitt, D.H.
Date : 2000.
Title : Localized permafrost dynamics and plant community structure and diversity in western Canadian bogs.
Publication : Quebec 2000: The Millennium Wetland Event, August 6 to 12, 2000, Quebec City, Quebec.
Issue :
Page(s) :
Abstract
At its southern limit, permafrost occurs exclusively as localized islands in boreal peatlands where distributions have been dynamic over the last millennium in response to climate change. A landform approach was taken to determine the effect of Little Ice Age permafrost aggradation and recent degradation on the structure and diversity of bog plant communities. We sampled the communities of 83 landscape features by a combination of quadrat (structure) and unbound (diversity) surveys at three study sites in each of Alberta, Saskatchewan and Manitoba. Permafrost aggradation results in communities that are clearly distinct from bog communities, changing from sparsely treed (<30% cover) and Sphagnum-dominated, to forested (>50 % cover) and feathermoss/lichen-dominated controlled by the degree of permafrost uplift. Degradation occurs rapidly and drowns permafrost vegetation as surfaces subside below the water table. Recolonization by wet-adapted communities is followed by rapid groundcover community change in a mostly treeless environment along a time/dryness gradient due to accelerated peat accumulation rates. Vegetation is thus spatially variable both within and between collapse sites due to differences in the timing and magnitude of collapse. Locally rare vascular and bryophyte species become common in some permafrost and collapse features, though overall landscape (gamma) diversity remains relatively stable. Similar changes can be expected as climatically sensitive localized permafrost continues to degrade throughout its distribution in western Canada.
Bibliography of Canadian Geomorphology