Tuesday, August 2, 2011

Ecological systems: Grasslands

Grasslands other than those of the Shortgrass Prairie in Colorado can be classified into three major groups: Western Great Plains Foothill and Piedmont Grassland, Southern Rocky Mountain Montane-Subalpine Grassland, and Inter-Mountain Basins Semi-Desert Grassland. Together these grasslands types cover about three million acres in our state.

Foothill and piedmont grasslands are found at the extreme western edge of the Great Plains, where increasing elevation and precipitation facilitate the development of mixed to tallgrass associations on certain soils. These grasslands typically occur at elevations between 5,250 and 7,200 ft. Typical species include big bluestem, little bluestem, needle-and-thread. 

 Foothill-piedmont grassland - Rocky Flats area.

Montane-subalpine grasslands in the Colorado Rockies are found at elevations of 7,200-10,000 feet, intermixed with stands of spruce-fir, lodgepole, ponderosa, and aspen forests, or as the matrix community in the large intermountain basin of South Park. Lower elevation montane grasslands are more xeric, while upper montane or subalpine grasslands are more mesic. Typical species include fescue, muhly, oatgrass, and others. 

Montane grassland - Mineral County

Colorado’s semi-desert grasslands are found primarily on dry plains and mesas of the west slope at elevations of 4,750-7,600 feet. These grasslands are typically dominated by drought-resistant perennial bunch grasses such as bluebunch wheatgrass, blue grama, galleta grass, and needle-and-thread, and may include scattered shrubs.

 Semi-desert grassland - Mesa County

Common species characteristic of these grasslands include the vesper sparrow, mountain bluebird, Brewer’s blackbird, and white-tailed jack rabbit. Rarer species are the Gunnison’s prairie dog and a variety of skipper butterflies. Impacts from human activity other than domestic livestock grazing are low for most of these grasslands, although a significant portion of historic occurrances have been lost through habitat conversion. The majority of Colorado’s grassland acreage is on privately owned lands, although much of the montane grasslands are on federal land managed by the USFS or the BLM. Although many of our remaining occurrences are in good condition, protection for these grasslands is generally lacking. 

Overall biodiversity, threat, and protection status scores for grasslands in Colorado.
A "windrose" graph depicting grassland status for individual scoring factors.

No comments:

Post a Comment

Thanks for your comment!

Please note that all comments are moderated, so there may be a delay of some hours (especially over the weekend or at night Colorado time) before your comment shows up.