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Ecoregions of
North Dakota
and
South Dakota

42. Northwestern Glaciated Plains


42g. Ponca Plains Level IV Ecoregion

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North Dakota Ecoregions

South Dakota Ecoregions

42a. Missouri Coteau

42b. Collapsed Glacial Outwash

42c. Missouri Coteau Slope

42d. Northern Missouri Coteau

42e. Southern Missouri Coteau

42f. Southern Missouri Coteau Slope

42g. Ponca Plains

42h. Southern River Breaks

42i. Glaciated Dark Brown Prairie

  The Northwestern Glaciated Plains ecoregion marks the westernmost extent of continental glaciation. The youthful morainal landscape has significant surface irregularity and high concentrations of wetlands. The rise in elevation along the eastern boundary defines the beginning of the Great Plains. Land use is transitional between the intensive dryland farming on Ecoregion 46i to the east and the predominance of cattle ranching and farming to the west on the Northwestern Great Plains (43).
The Ponca Plains comprise a transition area between the more densely settled farmland east of the Missouri River and J, the sparsely populated rangeland west of the river. Though not glaciated, this "west river" ecoregion resembles the adjacent Southern Missouri Coteau (42e) and Southern Missouri Coteau Slope (42f) in climate, physiography, and land use. Twenty to twenty-two inches of precipitation per year and level to slightly rolling terrain favor intensive rowcrop agriculture.

Physiography

Area (square miles): 969

Elevation/Local Relief (feet): 1900-2350/80-140

Unglaciated. Level to gently rolling plains. Preglacial stream drainage.

Geology

Surficial Material and Bedrock
Miocene soft sandstone (Arikaree Formation) and Cretaceous Pierre Shale.

Soil

Order (Great Groups)
Mollisols (Argiustolls, Calciustolls)

Common Soil Series
Reliance, Anselmo, Holt, Jansen

Temperature/Moisture Regimes
Mesic/Ustic

Climate

Precipitation - Mean annual (inches)
20-22

Frost Free - Mean annual (days)
130-160

Mean Temp. - Jan. min/max; July min/max, (°F)
7/32;60/89

Potential Natural Vegetation

Mixed-grass prairie: Little bluestem, prairie sandreed, green needlegrass and needleandthread.

Land Use and Land Cover

Intensive rowcrop agriculture for soybenas, corn, sunflowers, and alfalfa. Some grazing on Anselmo and Holt Soils.

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