Natural Wetlands Types and Distributions
Approximately 114,000 km2 of wetlands occur in Alberta, representing 18.0% of the province’s landbase. Most of these wetlands are peatlands (90.4%) found mainly within the Boreal Forest Natural Region (Figure 2). Nonpeat accumulating wetlands dominate the Parkland and Grassland Natural Regions (Figure 2). The distribution and type of wetland found within the province is controlled mainly by climate, specifically mean annual temperature and thermal seasonal seasonal aridity TSAI (total annual precipitation/mean growing season temperature) (Vitt et al. 1996). TSAI has also been identified as the primary factor controlling the southern limit of peatlands (Halsey et al. 1998).
The presence or absence of salts within the substrate also is a significant variable explaining wetland variation across the province. Areas of equivalent climates have much higher amounts of non peat accumulating wetlands when associated with solonetzic soils (Vitt et al. 1996). This can be related to the inability of mosses to establish viable communities were associated with salinity (Vitt et al. 1993).
Substrate texture and topography as well as bedrock geology have also been identified as important controls on wetland type and distribution (Halsey et al. 1997). Substrates with high hydraulic conductivity support soligenous (patterned) fens in climatically conducive areas, while non patterned fens and bogs are found associated with substrates of relatively low hydraulic conductivity. Wetlands are extensive in areas with minimal topography and poorly integrated drainage, particularly along major drainage divides such as Alberta’s northern uplands. Cover values are low in areas of steep slopes found along Alberta’s foothills (Vitt et al. 1996). In addition, acidic bedrock supports higher bog cover than calcareous bedrock where fens dominate (Halsey et al. 1997).
As factors of climate and geology control wetland type and distribution, changes in these parameters lead to corresponding changes in wetland type and distribution. For example, climatic change during the Holocene has lead to climatic shifts in wetland distributions (Halsey et al 1995; 1998), while climatic change predicted by greenhouse gas induced warming could have equally significant impacts on wetland distribution (Gorham 1991). Wetland types in the post reclaimed landscape may be significantly different than those present prior to mining as the geologic factors controlling wetland distribution have changed.