Alberta's Grassland Natural Region
Updated December 15, 2006
Native prairies and cultivated croplands on vast plains, grassy foothills, warm dry summers and cool, dry winters define the Grassland Natural Region. The semi-arid native prairies of southeastern Alberta merge gradually with taller grasslands and extensively cultivated lands to the north and west, reflecting increasing precipitation; trees grow only along rivers or in moist, protected locales.
The Grassland Natural Region includes the
level to rolling part of Alberta that is
sometimes called prairie. Although in its
natural state, prairie is thought of as an expanse
of grasses, shrublands are found in moister
areas. Even forests occur, but they are
restricted to coulees and river valleys.
The Grassland Natural Region includes the Dry Mixedgrass, Mixedgrass, Foothills Fescue and Northern Fescue Natural Subregions arrayed in concentric bands from the Alberta–Montana border north to the Grassland–Central Parkland Natural Subregion and west to its boundary with the Foothills Parkland and Montane Natural Subregions.
Chernozemic soils are characteristic of the Grassland Natural Region. Elevations range from about 550 m in the Dry Mixedgrass Natural Subregion near the Alberta– Saskatchewan border, to over 1500 m in the Foothills Fescue Natural Subregion and about 1450 m at the highest elevations of the Mixedgrass Natural Subregion on the Cypress Hills.
Undulating plains are characteristic of much of the Grassland Natural Region, with hummocky uplands also occurring in northern portions along with rolling terrain that is more characteristic of higher elevation areas to the west. Much of the Region has been cultivated, but the remaining native prairies and their associated soils reflect the interactions of dry, warm climates and topography.
Variations in the types of Chernozemic soils are used to differentiate Natural Subregions within the Grassland Natural Region, because extensive cultivation has removed much of the native vegetation and detailed maps of the remaining native plant communities are not available for the entire area. The boundaries between Natural Subregions in the Grassland Natural Region are not as clearly defined as those in the Rocky Mountain and Foothills Natural Regions, reflecting the more gradual influence of latitudinal changes on climate in the comparatively gentle prairie terrain.
The following links provides basic information on the key characteristics at the subregion level.
- Dry Mixedgrass Natural Subregion
The Dry Mixedgrass Natural Subregion is an expanse of level to gently undulating semiarid prairie, broken in places by coulees, valleys, badlands and dune fields. The warm, dry climate supports grasses, shrubs and herbs that are adapted to summer droughts. This Natural Subregion provides habitat for numerous species of plants and animals that occur nowhere else in Alberta.
- Dry southern prairies dominated by droughttolerant grasses, shrubs and herbs, or cultivated fields on moister or irrigated areas.
- Brown Chernozemic and Solonetzic soils.
- Trees absent except along rivers or in deep coulees where subsurface water is available.
- Hot summers, high solar inputs, high evaporation, and long cold winters with low snow cover.
The Dry Mixedgrass Natural Subregion is the largest of the four Natural Subregions in the Grassland Natural Region. It occupies the southeastern corner of Alberta at elevations from 550 m near Empress to 1100 m on the lower slopes of the Cypress Hills. Level to gently undulating glacial till or lacustrine plains are the dominant terrain type. Hummocky uplands and sand dunes also occur. Brown Chernozems are the dominant soils, but Brown Solonetzic soils have developed where saline and sodic conditions prevail. The warm, dry climate promotes the development of mixed-height grasslands composed of blue grama and needle-and-thread grass, with sand grass and June grass on sand dunes. Extensive low shrublands with silver sagebrush, silverberry, buckbrush and prickly rose occupy low-lying areas and northerly or easterly aspects. Tall shrub and tree stands are found in coulee or valley bottoms or on sandy soils with perched water tables, where the moisture supply is sufficient to support growth during the summer drought period.
- Mixedgrass Natural Subregion
The Mixedgrass Natural Subregion is a broad, fertile band of intensively cultivated prairie in south-central Alberta. Slightly higher precipitation than the Dry Mixedgrass Natural Subregion to the east has allowed intensive cultivation over most of the area. At higher elevations, native plains rough fescue and bluebunch fescue grasslands are dominant.
- Mostly cultivated with scattered remnant prairies; more extensive native rangelands at higher elevations.
- Slightly moister with somewhat cooler summers and milder winters than the Dry Mixedgrass Natural Subregion to the east.
- Dark Brown Chernozemic soils and grasses typical of moist areas in the Dry Mixedgrass Natural Subregion occupy average sites in this Subregion.
The Mixedgrass Natural Subregion curves north from the Alberta-Montana border to the Red Deer River in a 50 to 100 km wide band. Two outliers occur within the Dry Mixedgrass Natural Subregion at middle elevations in the Cypress Hills and on the Sweetgrass Upland along the Montana border. It is bounded on the west by the Foothills Fescue Natural Subregion, on the east by the Dry Mixedgrass Natural Subregion, and on the north by the Northern Fescue Natural Subregion. Elevations range from about 650 m near the Red Deer River to about 1450 m on the Cypress Hills.
Undulating and hummocky till plains, level lacustrine areas, and undulating to hummocky eolian deposits are typical landforms. Needleand- thread, porcupine grass, and northern and western wheatgrasses form communities on average sites in remnant prairie areas. Moister conditions on higher areas within the Natural Subregion allow plains rough fescue or bluebunch fescue to become dominant. Dark Brown Chernozems are the dominant soils, reflecting moister, somewhat cooler conditions than in the adjacent Dry Mixedgrass Natural Subregion.
- Northern Fescue Natural Subregion
A mosaic of cultivated fields and moist native prairie on undulating to hummocky terrain is characteristic of the Northern Fescue Natural Subregion. It represents a climatic transition between the Dry Mixedgrass Natural Subregion and the northern Central Parkland Natural Subregion.
- About 60 percent cultivated fields and 40 percent grazed native prairie.
- Cooler and moister than the adjacent southerly Mixedgrass and Dry Mixedgrass Natural Subregions; climatically similar to the adjacent Central Parkland Natural Subregion.
- Dark Brown Chernozemic soils are typical on average sites; plains rough fescue is the dominant grass on lightly grazed native range.
- About 60 percent cultivated fields and 40 percent grazed native prairie.
The Northern Fescue Natural Subregion occupies a 50 to 80 km-wide crescent, bordered on the north by the Central Parkland Natural Subregion and on the south and west by the Dry Mixedgrass, Mixedgrass and Foothills Fescue Natural Subregions. Elevations range from about 650 m near the Alberta-Saskatchewan border to nearly 1100 m on the Hand Hills southeast of Drumheller.
Hummocky to rolling hill systems with medium textured glacial till deposits occur to the east, south and west; the central portion is a gently undulating fine textured till and lacustrine plain. Plains rough fescue-dominated communities are found on average sites in remnant prairie areas. Drier than average sites in the Northern Fescue Natural Subregion support grasses typical of sites with average moisture in the Mixedgrass and Dry Mixedgrass Natural Subregions; moister sites support shrublands.
Dark Brown Chernozems are the dominant soils, reflecting moister, cooler conditions than in the adjacent Dry Mixedgrass Natural Subregion. Solonetzic soils associated with saline and sodic soils are common in the central plains area.
- Foothills Fescue Natural Subregion
Nearly level cultivated plains in the north and cool, high-elevation grassy uplands along the mountain flanks to the south characterize the Foothills Fescue Natural Subregion.
- Cooler summers and shorter growing seasons, but warmer winters and more precipitation than other grassland Natural Subregions.
- Black Chernozemic soils are typical on average sites; mountain rough fescue and bluebunch fescue are the dominant grasses on lightly grazed native range.
- Grasslands have a diverse herb component, with a number of species not prominent in the other grassland Natural Subregions, such as sticky purple geranium and silvery perennial lupine.
- Fifty percent cultivated, with about 80 percent native prairie in the south at higher elevations.
The Foothills Fescue Natural Subregion occupies an irregular south-north belt between 15 to 100 km wide, extending north from the Alberta-Montana border to northwest of Drumheller. Adjacent Natural Subregions are the Central Parkland and Northern Fescue to the north, the Foothills Parkland to the west, and the Mixedgrass to the east. It lies directly adjacent to the Montane Natural Subregion at lower elevations in the Porcupine Hills and in the Crowsnest Pass area. This is the highest grassland Natural Subregion, with elevations ranging from 800 m in the north near Drumheller to over 1500 m on the east slopes of the Porcupine Hills.
Rolling to hummocky uplands are typical of the southern and western portions of this Subregion, with undulating plains to the north and east. Mountain rough fescue-dominated communities are found on average sites in remnant prairie areas, but most of the area is cultivated. Black Chernozems are the dominant soils, reflecting moister, cooler conditions and the incorporation of relatively high organic matter. Open water and wetlands are uncommon in the hillier foothills area.
The new Natural Regions and Subregions of Alberta Report (5.2 MB) is now available.
View the Errata Report(23 KB) for the printed and digital versions of the above report, prior to May 15 2006.