Central Lowlands

eastern North Dakota, South Dakota, Nebraska, and Kansas; central Oklahoma, northcentral Texas; Minnesota, Iowa, northern Missouri

Land-Surface Form

The Central Lowlands cover an extensive area, with alternating prairie and deciduous forest. The topography is mostly gently rolling plains, but steep bluffs border a number of valleys. Some areas are nearly flat; others have high rounded hills. Elevations range from 300 to 2,000 ft (90 to 600 m). The far northern portion of the area has been glaciated, and the Mississippi River flows along the eastern edge of the lowlands.

Aquatic Resources

The upper Mississippi River forms the upper third of the eastern border of the Central Region. The last sections of the Lower Missouri River separate the Central Lowlands in Missouri from the Ozark Plateau and Ouachita Mountains. The major rivers found in the Central Lowlands are: 1) Minnesota, Des Moines, James, and Kansas Rivers in their entirety; 2) lower half of the Missouri River; 3) headwaters and upper sections of the Red River in North Dakota and the Trinity River; 4) Platte, Republican, and Smoky Hill River mouths; 5) lower Cimarron River and mouth; 5) middle Arkansas River, and 6) upper Red River in Texas. The ground water of the Central Lowlands is characterized by the confined Jordan aquifer, which underlies most of Iowa and is the most extensively used aquifer in Iowa. Numerous other confined aquifers also occur in the Central Lowlands. Water from the aquifers of the Central Lowlands is extracted for a wide range of uses such as irrigation, livestock watering, and municipal water supplies.

Additionally, within the Central Region there are many natural and man-made impoundments within the Central Lowlands such as the glacially-formed Minnesota Finger Lakes area and numerous large hydropower and flood control reservoirs produced by man-made dams on the Missouri river.

Climate

Summers are usually hot, and winters are cold, especially in the northern part of the province. Average annual temperatures may reach 40^oF (4^oC) in the north and 65^oF (20^oC) in the south. Winters are short and relatively mild in southerly areas. Average annual precipitation ranges from 20 to more than 40 in (510 to 1,020 mm), falling mainly during the growing season.

Vegetation

Vegetation is primarily forest-steppe, characterized by intermingled prairie, groves, and strips of deciduous trees. The alternation of forest and prairie in the western part results chiefly from local soil conditions and slope exposure; trees are commonly found near streams and on north facing slopes.

Grasses are the dominant prairie vegetation. Most are moderately tall and usually grow in bunches. The most prevalent type of grassland is bluestem prairie, dominated by plants such as big bluestem, little bluestem, switchgrass, and Indian grass, along with many species of wildflowers and legumes. Due to generally favorable conditions of climate and soil, most of the area is cultivated, and little of the original vegetation remains.

The upland forest in dominated by oak and hickory, becoming savannalike where it gradually turns into prairie. On floodplains and moist hillsides, the deciduous forest is richer. In the western part of the area, it includes eastern cottonwood, black willow, and American elm. In central Minnesota south through northeastern Iowa, maple-basswood forest is dominated by sugar maple and American basswood.

Fauna

In addition to prairie animals that do not need woody vegetation, many forest animals are found in this province. Few forms are peculiar to the region, but certain mammals are indicative of its riverine forest, including mink and river otter. On the prairies, thirteen-lined ground squirrels and blacktail prairie dogs are commonly seen. In the oak-hickory forest, acorns and hickory nuts provide abundant food for the gray squirrel.

Birds of the riverine forests include the belted kingfisher, bank swallow, spotted sandpiper, and green-backed heron. Upland birds include the horned lark, eastern meadowlark, and mourning dove. Forested areas include blue jays, scarlet or summer tanagers, rose-breasted grosbeaks, and ovenbirds.

Common fish fauna found in the Central Lowlands include the shovelnose sturgeon, paddlefish, gar, American eel, trouts, pickerels, common carp, chubs, darters, shiners, suckers, catfishes, black basses, and sunfishes. Threatened or endangered fish fauna found in the Central Lowlands include the Neosho madtom and pallid sturgeon.

References