Boundaries

This is a small ecoregion covering parts of southern Alberta and western Saskatchewan. It is bounded by the upper North and South Saskatchewan rivers and their drainages, flowing from the Canadian Rockies in the west to the prairies in the east.

Topography

The western side of the ecoregion is bounded by the Rocky Mountains of Alberta, with the largest peaks rising over 3000 m around the Columbia Icefield. Great cliffs with precipitous faces of grey carbonate strata and rocky outcrop peaks are characteristic features. The foothills are comprised of linear ridges, rolling plateau remnants and broad valleys. The lower reaches of Red Deer River traverses the Badlands, which are dramatic land formations scoured and eroded by water, and etched by weathering and wind-driven sand and rain. In the prairies, there is flat-lying Paleozoic limestone bedrock covered with glacial till, lacustrine silts and clays, and peat deposits. Cretaceous shale with shallow depressions has caused small, shallow lakes and ponds to form.

Freshwater habitats

Rivers begin as high-gradient streams and flow off the mountains becoming slower, wider streams as they flow through the semi-arid prairies. Habitats range from fast-flowing whitewater to slow, meandering rivers in deep and wide valleys. Some streams of this ecoregion have become anastomosed (connected), a result of flowing over formerly glaciated land that is in a state of gradual uplift. These streams have braided channels which tend to contain uncommon freshwater habitats.

The well-watered parts of this ecoregion also contain important wetlands. Canada holds one-fourth of the world’s wetlands, and the province of Saskatchewan has about 17% of Canada’s total. These wetlands provide important habitat for rare and imperiled birds, such as piping plovers (Charadrius melodus), whooping cranes (Grus americana), and trumpeter swans (Cygnus buccinator).

Terrestrial habitats

The vegetation of the ecoregion ranges from temperate coniferous forests to grasslands. To the west, alpine and subalpine ecosystems have mixed forests of lodgepole pine (Pinus contorta), Engelmann spruce (Picea engelmannii), and alpine fir (Abies lasiocarpa), with quaking aspen (Populus tremuloides), white spruce (Picea glauca), balsam poplar (P. balsamifera), paper birch (Betula papyrifera) and balsam fir (Abies balsamifera) in the foothills. Heather (Ericaceae), sedges (Carex spp.) and mountain avens (Dryas hookeriana) also occur. Black spruce (P. mariana) and tamarack (Larix laricina) occur in marshy areas. To the north, quaking aspen, balsam poplar, and bur oak (Quercus macrocarpa) occur. White spruce and balsam fir are present in areas unaffected by fires, and jack pine (Pinus banksiana) occurs on drier, sandy sites. Wet areas have sedges (Carex spp.), willow (Salix spp.), black spruce (P. mariana), and tamarack (Larix laricina). Grasslands to the south are usually a mixture of tallgrass and shortgrass prairies, and include grama (Bouteloua gracilis), little bluestem (Schizachrium scoparium), needle-and-thread grass (Stipa comata), wheatgrass (Agropyron smithii), threadleaf sedge (Carex filifolia), and junegrass (Koelaria cristata). The short grasslands include spear grass (Poa annua), blue grama grass, wheatgrass, and dryland sedge. Shrubs, such as sagebrush (Artemesia tridentata), are common, and on drier sites yellow cactus and prickly pear (Opuntia spp.) can be found.

Description of endemic fishes

The Upper Saskatchewan ecoregion, like most of the rest of Canada, was subjected to heavy glaciation as recently as 10,000 to 15,000 years ago.  A sculpin species, the Eastslope sculpin (Cottus sp.), may represent the only species endemic to this ecoregion. However, further taxonomic studies are required to determine the validity and geographic extent of this species. The area contains no other endemic fish, mussels, crayfish, or aquatic herpetofauna.

Other noteworthy fishes

The lake sturgeon (Acipenser fulvescens), once very abundant, has virtually disappeared as a result of overexploitation and barriers to dispersal. Native westslope cutthroat trout (O. clarkii clarkii) in the foothills of the Rocky Mountains have declined dramatically largely as a result of hybridization with introduced rainbow trout (O. mykiss). Several aquarium fish species (green swordtail (Xiphophorius hellerii), African jewelfish (Hemichromis letourneuxi)) have been introduced and have become established in Banff Hot Springs. These species are thought to be responsible for the decline of several native species.

Ecological phenomena

Historically, the lake sturgeon likely undertook long spawning migrations.

Justification for delineation

The ecoregions of Canada were identified based on the faunal similarity of 166 major watersheds based on a cluster analysis of freshwater fish occurrences in these watersheds. The Upper Saskatchewan ecoregion is comprised of the upper Saskatchewan River watershed extending from the Canadian Rockies in the west to the prairies in the east. The fish fauna is a mix of Rocky Mountain foothill and prairie species, primarily originating from a Mississippian refugium.

Level of taxonomic exploration

Good / Fair