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Ecoregions of
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| 43g. Semiarid Pierre Shale Plains | Level IV Ecoregion |
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43f. Subhumid Pierre Shale Plains |
The Northwestern Great Plains
ecoregion encompasses the Missouri Plateau section of the Great
Plains. It is a semiarid rolling plain of shale, siltstone, and sandstone
punctuated by occasional buttes and badlands. Native grasslands persist
in areas of steep or broken topography, but they have been largely replaced
by spring wheat and alfalfa over most of the ecoregion. Agriculture
is limited by erratic precipitation patterns and limited opportunities
for irrigation.
West of the Cheyenne river, the Semiarid Pierre Shale Plains take on a drier aspect. Although the precipitation is only one or two inches less per year than in ecoregion 43f, successful yields for tilled crops occur more infrequently than they do further east. In this region the mixed-greass prairie has a predominance of shortgrass species, e.g., little bluestem and buffalograss.
Physiography Area (square miles): 3853 Geology Surficial Material and Bedrock Soil Order (Great Groups) Climate Precipitation - Mean annual (inches) Potential Natural Vegetation Shortgrass prairie grasses such as western wheatgrass, green needlegrass, blue grama and buffalograss. Land Use and Land Cover Cattle grazing, rangeland. Dryland farming of winter wheat and alfalfa. |
