Montana Valley and Foothill grasslands
|Montana Valley and Foothill grasslands|
Bison at the National Bison Range
|Biome||Temperate grasslands, savannas, and shrublands|
|Area||31,500 km2 (12,200 sq mi)|
|Countries||United States and Canada|
|States||Montana and Alberta|
This area consists of rolling grassy hills and river valleys of the Rocky Mountains foothills in the US state of Montana and the Canadian province of Alberta. The area largely consists of the Rocky Mountain Front, where the Great Plains rise to meet the Rockies, and is thus near the Continental Divide. The foothills are drained by the upper Missouri River and the Clark Fork/Bitterroot River systems among others. The ecoregion also contains outlying disconnected areas of similar habitat such as valleys of the Bow River in Alberta. The area has a moderate clmate, warmed by the Chinook wind which brings dry, warm summers (average 14°C) and winters that are mild for this latitude (ave. -8°C).
While the dominant vegetation are grasses such as rough fescue with Parry's oatgrass and Koeleria (June grasses) the foothills are rich in plant life with, for example, 487 species of plant counted in southwest Montana's Centennial Valley. The ecoregion also contains sagebrush country in the higher and drier valleys in the rain shadow of the Rockies such as the upper Madison, Ruby and Red Rock Rivers, which are a similar habitat to the neighbouring Snake-Columbia shrub steppe ecoregion. Finally the ecoregion contains parts of the Prairie Pothole Region, large areas of wetland and rich grass on the Rocky Mountain Front steppe. Traditionally the grassland was reduced and then renewed by a combination of heavy grazing by bison and other ungulates and regular fires.
The traditional wildlife of this area of included the large herds American bison, elk and bighorn sheep observed during the Lewis and Clark Expedition in the early 19th century but which now remain in small numbers only. Another iconic mammal found here are the grizzly bears, which come down from the mountainsides to forage in the rich habitats of rivers and grasslands. This is the last remaining area in the United States where grizzlies come down to the Great Plains. Other mammals of the valleys include White-tailed deer, wolves, mountain lions, mule deer, pronghorn and ground squirrels. Birds spotted in the Centennial Valley for example include grouse, sandhill crane and trumpeter swan.
Threats and preservation
About 25% of the original grassland remains (less than 10% in Canada). However the population of the Rocky Mountains is growing and the towns and cities of the valleys, in Montana and in Alberta are continually expanding, removing habitat and blocking the movements of grizzly bear, elk, mule deer and others. Building is most intense in Paradise Valley on the Yellowstone River just north of Yellowstone National Park, Bitterroot Valley, and the Gallatin River Valley around Bozeman. The area also contains the largest Superfund toxic waste site in the United States, including Milltown Reservoir and the former open pit copper mine Berkeley Pit on the upper Clark Fork near Butte as far as Missoula, Montana. The area also has potential for oil and gas development which would have further serious effects on habitats.
Areas of realitively intact grassland and wetland on the Rocky Mountain Front include the Pine Butte Swamp Preserve near Choteau, Montana, parts of the Blackfeet Indian Reservation, and a number of other hills and valleys of southwestern Montana including the Centennial Mountains, the Big Hole River and parts of the Madison River valleys. Protected areas include Red Rock Lakes National Wildlife Refuge in Centennial Valley, Pine Butte Swamp, the National Bison Range in western Montana and a number of Bureau of Land Management wilderness study areas.
- Hoekstra, J. M.; Molnar, J. L.; Jennings, M.; Revenga, C.; Spalding, M. D.; Boucher, T. M.; Robertson, J. C.; Heibel, T. J. et al. (2010). Molnar, J. L., ed. The Atlas of Global Conservation: Changes, Challenges, and Opportunities to Make a Difference. University of California Press. ISBN 978-0-520-26256-0.
- "Montana Valley and Foothill grasslands". Terrestrial Ecoregions. World Wildlife Fund.