Climatic and physiographic controls on wetland type and distribution in Manitoba, Canada
Canadian Forest Service
Wetlands represent a substantial part of Manitoba's terrestrial landscape, covering 233,340 kru' or 43% of the province; peatlands represent 90% of all wetlands. A wetland inventory for Manitoba is presented following a classification scheme grounded in wetland function, vegetation, and landform. The province is subdivided into twelve wetland regions each having distinctive wetland types and abundances. A hybrid Oetrended Canonical Correspondance Analysis (OCCA) indicates that wetland distribution in the province is largely controlled by allogenic factors of climate and physiography, The first canonical axis represents the variance in wetland distribution occurring along a north-to-south gradient within the province. In northern Manitoba, permafrost bogs dominate, replaced southwards by bogs without permafrost and fens with and without internal lawns. Farther south, peatlands are replaced by non-peat-accumulating wetlands. This wetland distributional gradient is most strongly correlated to mean annual temperature, with thermal seasonal aridity, annual precipitation, and moisture deficit (precipitation-potential evaporation) also significant. Significant allogenic variables correlated to the first canonical axis are not restricted to climate alone. The type of bedrock geology in the area also plays an important role in determining wetland distribution, with bogs occurring preferentially in areas of acidic bedrock, while fens are found on calcareous bedrock, The second canonical axis represents a surface-water flow gradient, with patterned fens and marshes having relatively large amounts of surface-water flow on one end and nonpermafrost bogs and swamps with low amounts of surface-water flow on the other. Texture of the subsurface is the most important variable explaining the second axis, with sediments having high hydraulic conductivity correlated to wetlands with high surface-water flow, while sediments with low hydraulic conductivity are related to wetlands with low surfacewater flow. Annual precipitation is also a statistically significant variable explaining the variance in wetland distribution along the second axis.
wetlands, peatlands, mires, permafrost, land classification, remote sensing, Manitoba
Climatic and physiographic controls on wetland type and distribution in Manitoba, Canada. 1997. Halsey, L.A.; Vitt, D.H.; Zoltai, S.C. Wetlands 17(2): 243-262