CGRG Bibliography of Canadian Geomorphology
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Author : Gignac, L.D.; Halsey, L.A.; and Vitt, D.H.
Date : 2000.
Title : A bioclimatic model for the distribution of Sphagnum-dominated peatlands in North America under present climatic conditions.
Publication : Annual Scientific Meeting, Canadian Geophysical Union, Banff, Alberta, May 23-27, 2000.
Issue : Abstract.
Page(s) :
Abstract
A model is developed that projects the climatic and geographic distribution of Sphagnum-dominated peatlands in western Canada and North America. The model is based on the relationship between the abundance of Sphagnum species on 640 peatland sites located in proximity to permanent weather stations in western Canada and three climatic variables: mean annual temperature (MAT), mean annual total precipitation (MATP), and a summer moisture index (P-PET). The percent cover of Sphagnum species was quantified for all possible combinations of MAT and MATP found in western Canada. Abundance values were expanded to include all climatic values in North America, by interpolating within the matrix of values for western Canada using distance-weighted means. Grid nodes that had Sphagnum abundance values > 50% were identified as having Sphagnum-dominated peatlands present while those having abundance values < 50% were identified as being absent. Since Sphagnum-dominated peatlands do not occur in areas having summer P-PET values <-6 cm, that value was also included in the model. The result produced a matrix of 3360 grid nodes where each node was characterized by MAT and MATP values, the minimum summer P-PET value, and the presence or absence of Sphagnum-dominated peatlands. The climatic data in the model was then match merged with the MAT, MATP, and summer P-PET values obtained from Leemans & Cramer (1991). The latter data also contained geographic data on a 0.5-degree latitude by longitude grid. The merged data contained all possible 0.5-degree latitude and longitude grid cells in North America, MAT, MATP, and summer P-PET values for each grid cell, and a value indicating the presence or absence of Sphagnum-dominated peatlands. Based on the merged data, the geographic distribution of Sphagnum-dominated peatlands was then mapped for western Canada and North America. Those maps were then compared to the actual distribution of Sphagnum-dominated peatlands. Results of those comparisons indicated that the model‚s projections matched the southern distribution of Sphagnum-dominated relatively closely. Results for the northern distribution however were not as accurate as those for the southern distribution. The overall accuracy is approximately 80%. However some of those errors were caused by inaccurate climatic data that resulted from the lack of permanent weather stations in northern areas and the lack of definition in the northern limits of the actual distribution of bogs and poor fens. In areas where both the climatic data and the actual distribution of Sphagnum-dominated peatlands are accurate, the model accuracy was approximately 90%.
Bibliography of Canadian Geomorphology