South Dakota Ecoregions
Omernik Level IV ecoregions (references below)
Click on a region below for a brief ecoregion description.
17a - Black Hills Foothills - Elevation 3300 - 4900 ft.
Composed of the Hogback Ridge and the Red Valley. Each forms a concentric ring around the mountainous core of the Black Hills (ecoregions 17b and 17c). Ponderosa pine covers the crest of the hogback and the interior foothills. Buffalo, pronghorn, deer, and elk still graze the Red Valley grasslands in Custer State Park.
17b - Black Hills Plateau - Elevation 3500 - 5500 ft.
This ecoregion is a relatively flat, elevated expanse covering the mid-elevation slopes and grasslands of the Black hills. It includes areas of sharply tilted metamorphic rock and lower elevation granite outcrops. Competing uses, such as logging, farming and ranching, and tourist development stress this ecosystem.
17c - Black Hills Core Highlands - Elevation 5500 - 7242 ft.
In the Black Hills Core Highlands, higher elevations, cooler temperatures, and increased rainfall foster boreal species such as white spruce, quaking aspen, and paper birch. The mixed geology of this region includes the highest portions of the limestone plateau, areas of schists, slates and quartzites, and large masses of granite that form the most prominent peaks.
25a - Pine Ridge Escarpment - Elevation 3000 - 3700 ft.
The Pine Ridge Escarpment forms the boundary between the Missouri Plateau to the north and the High Plains to the south. Ponderosa pine clothe the northern face and the ridgecrest outcrops of sandstone. Cattle graze the rolling grasslands of the Pine Ridge Indian Reservation. A mixed-grass prairie vegetation, rather than shortgrass prairie, dominates this northern extremity of the Western High Plains.
42a - Missouri Coteau - Elevation 1650 - 2100 ft.
Like closely-space ocean swells, the rolling hummocks of
the Missouri Coteau enclose countless wetland depressions or potholes.
During its slow retreat, the Wisconsinan glacier stalled on the Missouri
escarpment for thousands of years, melting slowly beneath a mantle of sediment
to create the characteristic pothole topography of the Coteau.
The wetlands of the Missouri Coteau and the neighboring prairie pothole
regions are major waterfowl production areas in North America.
Land use on the coteau is a mixture of tilled agriculture in flatter
areas and grazing land on steeper slopes.
42c - Missouri Coteau Slope - Elevation 1700 - 2450 ft.
The Missouri Coteau Slope ecoregion declines in elevation
from the Missouri Coteau (42a) to the Missouri River. Unlike the Missouri Coteau (42a) where there is a paucity of
streams, the Missouri Coteau Slope has a simple drainage pattern and fewer
wetland depressions. Due to the
level to gently rolling topography, there is more cropland than on the Missouri
Coteau (42a). Cattle graze on the
steeper land that occurs along drainages.
42e - Southern Missouri Coteau - Elevation 1500 - 2100 ft.
The Southern Missouri Coteau ecoregion, located on the
southern fringe of continental glaciation, exhibits a muted coteau topography;
gentle undulations rather than steep hummocks, smaller areas of high wetland
density, and more stream erosion backcutting into areas of internal drainage.
There is more tilled land on the Southern Missouri Coteau than on the
Missouri Coteau (42a) because of its gentler topography.
More soybeans and corn are planted on the Southern Missouri Coteau due to
its milder climate and increased precipitation.
42f - Southern Missouri Coteau Slope - Elevation 1400 - 2200 ft.
The Southern Missouri Coteau Slope differs from the
Missouri Coteau Slope (42c) to the north; it has mesic soils rather than frigid
soils and a substantial cap of rock-free loess.
To the south, the coteau areas east of the Coteau Slope ecoregions (42c,
42f) become progressively narrower and more eroded. The level to rolling uplands of the Southern Missouri Coteau
Slope are planted in sunflowers, wheat, millet, and barley.
Corn is a marginal crop that does well in wet years.
The stream drainages tend to be grazed.
Willows, green ash, and elm grow in the riparian areas.
42g - Ponca Plains - Elevation 1900 - 2350 ft.
The Ponca Plains comprise a transition area between the more densely settled farmland east of the Missouri River and 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.
42h - Southern River Breaks - Elevation 1250 - 2000 ft.
The Southern River Breaks reflect the more temperate
conditions of the southern glaciated plains.
Here the draws and northern aspects are heavily wooded with deciduous
forest, in contrast to the River Breaks (43c) north of the Big Bend of the
Missouri, where the riparian woodland forms narrow stringers of juniper and
43a - Missouri Plateau - Elevation 1750 - 3300 ft.
On the Missouri Plateau, west of the Missouri River, the
landscape opens up to become the “wide open spaces” of the American West.
The topography of this ecoregion was largely unaffected by glaciation and
retains its original soils and complex stream drainage pattern.
A mosaic of spring wheat, alfalfa, and grazing land covers the shortgrass
prairie where herds of bison, antelope, and elk once ranged.
43c - River Breaks - Elevation 1300 - 2700 ft.
The River Breaks form broken terraces and uplands that descend to the Missouri River and its major tributaries. They have formed particularly in soft, easily erodible strata, such as Pierre shale. The dissected topography, wooded draws, and uncultivated areas provide a haven for wildlife. Riparian gallery forests of cottonwood and green ash persist along major tributaries such as the Moreau and Cheyenne rivers, but they have largely been eliminated along the Missouri River by impoundments.
43d - Forested Buttes - Elevation 3100 - 3650 ft.
The Forested Buttes of northwestern South Dakota, outliers
of more extensive buttes in Montana, stand 500 feet above the surrounding
plains. On closer inspection, the
seemingly flat-topped mesas offer a landscape of eroded knobs, hoodoos, and
grassy toeslopes capped by ponderosa pine.
The higher elevation, locally increased moisture, and variable aspects in
the dissected topography are conducive to tree growth.
Green ash, boxelder, snowberry, and upland juniper grow in the draws.
Cattle, buffalo, mule deer, and pronghorns share the rangeland.
43e - Sagebrush Steppe - Elevation 3000 - 3475 ft.
The Sagebrush Steppe occurs on the dry western edge of
North and South Dakota where rainfall rarely exceeds 14 inches per year.
Eroded buttes, Hell Creek badlands, scoria (burnt coal) mounds, and salt
pans punctuate a thick mat of shortgrass prairie and dusky gray sagebrush.
The region is characterized by low human population, minimal cultivation,
and relatively high concentrations of wildlife.
43f - Subhumid Pierre Shale Plains - Elevation 1700 - 2800 ft.
A continuous vegetation cover is essential to keep the
Subhumid Pierre Shale Plains intact. Tilling
the rolling hillsides risks wind and water erosion.
Stream channels are deeply incised in its soft, black shale soils and
slumping is common along exposed banks.
43g - Semiarid Pierre Shale Plains - Elevation 2500 - 3700 ft.
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 the Subhumid
Pierre Shale Plains (43f), successful yields for tilled crops occur more
infrequently than they do further east. In
this region the mixed-grass prairie has a predominance of shortgrass species,
e.g., little bluestem and buffalograss.
43h - White River Badlands - Elevation 2450 - 3250 ft.
The spectacular White River Badlands formed through the erosion of the soft Brule and Chadron clays and siltstones. The turbulent topography ranges from the sheer, highly dissected “Wall” to pastel-hued toeslopes laden with Oligocene fossils. This seemingly barren landscape is broken by grass-covered, perched “sod tables” that may be grazed or tilled.
43i - Keya Paha Tablelands - Elevation 2250 - 3600 ft.
The Keya Paha Tablelands form a perimeter of sandy, level
to rolling plains that surround the steeper dune topography of the Nebraska Sand
Hills (44a). Ponderosa pines grow
in the drainages in the hilly land east of the Pine Ridge escarpment.
Millet and corn grow on the level land, but the sandy soil limits
43j - Moreau Prairie - Elevation 2100 - 3200 ft.
Occasional buttes, areas of badlands, and numerous salt
pans appear on the Moreau Prairie. The soils derived from the Hell Creek formation tend to be
alkaline, and make this ecoregion less productive agriculturally than the areas
surrounding it. Most of the region
is grazed by cattle, sheep, and pronghorn.
43k - Dense Clay Prairie - Elevation 2700 - 3500 ft.
The Dense Clay Prairie differs from the surrounding
ecoregions in its lack of vegetative cover.
The grassland in this ecoregion is missing its short- and mid-level
layers. Only the tall grasses show
thinly against the dark-colored clay. Riparian
woodland is absent from draws and stream corridors.
This fragile landscape must be managed carefully to avoid erosion and
blowing soil. Sheep farming is the
major land use.
44a - Nebraska Sand Hills - Elevation 2900 - 3500 ft.
The profile of wavelike dunes on the horizon and a broad
expanse of sky characterize this northern outpost of the Nebraska Sand Hills.
Cattle ranching is the predominant land use in the region.
The prairie grass associations are specific to the sand environment, but
the fragile vegetative cover is susceptible to blowouts, prompting ranchers to
employ rotational grazing strategies to maintain it.
46c - Glacial Lake Basins - Elevation 1300 - 1585 ft.
The Glacial Lake Basins were once occupied by Lake Souris,
Devils Lake, and Lake Dakota. These
proglacial lakes were formed when major stream or river drainages were blocked
by glacial ice during the Pleistocene. The
smooth topography of the Glacial Lake Basins, even flatter than the surrounding
drift plains, resulted from the slow buildup of water-laid sediments.
The level, deep soils on the lake plains are intensively cultivated.
In the north, the primary crops are spring wheat, other small grains, and
sunflowers; in the Lake Dakota basin of South Dakota, corn and soybeans are more
46d - Glacial Lake Deltas - Elevation 1290 - 1595 ft.
The Glacial Lake Deltas were deposited by rivers entering
glacial lake basins (e.g., Glacial Lake Souris, Devils Lake, and Lake Dakota). The
heaviest sediments, mostly sand and fine gravel, formed delta fans at the river
inlets. As the lake floors were exposed during withdrawal of
the glacial ice, wind reworked the sand in some areas into dunes.
46e - Tewaukon Dead Ice Moraine - Elevation 1100 - 1380 ft.
The Tewaukon Dead Ice Moraine is a continuation of the Prairie Coteau (46k) that extends below the level of the Prairie Coteau Escarpment (46l). A high density of semipermanent wetlands provide feeding and nesting habitat for dabbling ducks (blue-winged teal and mallard), and diving ducks (redhead and canvasback). Most upland areas are used for cultivated crops.
46i - Drift Plains - Elevation 1080 - 2000 ft.
On the Drift Plains, the retreating Wisconsinan glaciers
left a subtle undulating topography and a thick mantle of glacial till.
A greater proportion of temporary and seasonal wetlands are found on the
drift plains than in the coteau areas, where semipermanent wetlands are
numerous. Because of the productive
soil and level topography, this ecoregion is almost entirely cultivated, with
many wetlands drained or simply tilled and planted.
However, valuable waterfowl habitat still remains, concentrated in state
and federally sponsored duck production areas.
The historic grassland on the Drift Plains was a transitional mix of
tallgrass and shortgrass prairie. The
prairie grasses have been largely replaced by fields of spring wheat, barley,
sunflowers, and alfalfa.
46k - Prairie Coteau - Elevation 1500 - 2010 ft.
The Prairie Coteau ecoregion, like the Missouri Coteau
(42a), is the result of stagnant glacial ice melting beneath a sediment layer.
The tightly undulating, hummocky landscape has no drainage pattern; it is
perforated with closely spaced semipermanent and seasonal wetlands.
However, the Prairie Coteau differs from ecoregion 42a in two ways.
It has a chain of lakes that were formed where there was little ice
shear, and higher precipitation levels that allow widespread burr oak woodlands
near wetland margins.
46l - Prairie Coteau Escarpment - Elevation 1250 - 2000 ft.
The Prairie Coteau Escarpment ecoregion, though small, is a
distinctive ecosystem, rising 300 to 600 feet in elevation from the Minnesota
River valley to the brow of the Prairie Coteau (46k). The elevation, broken topography, and sufficient
precipitation favor dense deciduous forest growth in riparian areas. Cool, perennial streams flow off the escarpment, providing
habitats and oxygenated water not found elsewhere in eastern South Dakota.
46m - Big Sioux Basin - Elevation 1625 - 1990 ft.
The Big Sioux Basin is a trough penetrating the core of the Prairie Coteau (46k). Its topography was affected by pre-Wisconsinan glaciation; later advances of the Wisconsin glacier diverged around the basin. In contrast to the neighboring Prairie Coteau (46k), the basin has a well-developed drainage network. There is more tilled land in the Big Sioux basin due to the relative paucity of wetlands and the gentler topography.
46n - James River Lowland - Elevation 1200 - 1850 ft.
The boundary between the James River Lowland and the Drift
Plains (46i) to the north represents a broad phenological and climatic
transition zone. This ecoregion is
characterized by mesic soils, warmer temperatures, and a longer growing season
than the Drift Plains (46i). These
differences are reflected in the crop types of the region.
Winter wheat, corn, and soybeans are more prevalent in this ecoregion’s
46o - Minnesota River Prairie - Elevation 1050 - 1300 ft.
Thick glacial drift comprises the level terrain of the
Minnesota River Prairie. Wetlands
are common, though they are fewer and less persistent than those in the
neighboring stagnation moraines (ecoregions 46e and 46k).
The desiccating winds and
historic fire regime promoted the prairie ecosystem in this region; however, it
is transitional to woodland that occurs to the north and east in Minnesota.
Today, the original tallgrass prairie has been replaced by intensive
agriculture for grain, corn, and soybeans.
47a - Loess Prairies - Elevation 1200 - 1700 ft.
The Loess Prairies of Iowa and South Dakota surround the
perimeter of the Des Moines lobe of the Late Wisconsinan glaciation.
Of the two areas in South Dakota, the northern one is distinguished from
neighboring regions by its rock-free soil and a paucity of wetlands.
The southern area is more highly dissected, with deciduous woodland and
brush on the steeper slopes and in the draws.
47d - Missouri Alluvial Plain - Elevation 1100 - 1200 ft.
The human development of the Missouri Alluvial Plain over
the last two centuries has separated the Missouri River from its floodplain.
A system of dams, levees, and stream channelization has largely
controlled the flood cycles to allow intensive agriculture in the river
bottomland. Much of the northern
floodplain forest has been cut, and oxbow lakes and wetlands have been drained
to reclaim additional agricultural land.
48a - Glacial Lake Agassiz Basin - Elevation 790 - 1200 ft.
From the Pembina Escarpment (46a), the view of the Glacial Lake Agassiz Plain is of an extremely flat patchwork of cultivated farmland. Because the Red River of the North has a poorly defined floodplain and very low gradient, flooding can be a problem. Outside of channelized areas in the floodplain, turbid valley streams meander within narrow buffer strips of cottonwood, elm, ash, and willow. Soils range from silty to clayey in texture. Most have high water tables and are extremely productive.
Ecoregion summaries from "Ecoregions of North and South Dakota", U.S. EPA published map. Primary authors: Sandra A. Bryce (Dynamac Corporation), James M. Omernik (USEPA), David E. Pater (Dynamac Corporation), Michael Ulmer (USDA), Jerome Schaar (NRCS), Jerry Freeouf (USFS), Rex Johnson (SDSU), Pat Kuck (DENR/NRCS Liason), and Sandra Azevedo (OAO Corporation).
For explanations of USEPA's ecoregions and the methodology to derive them, check out:
Omernik, J.M., 1987, "Ecoregions of the conterminous United States (map supplement)": Annals of the Association of American Geographers, v. 77, no. 1, p. 118-125.
Gallant, A.L., Whittier, T.R., Larsen, D.P., Omernik, J.M., and Hughes, R.M., 1989. "Regionalization as a tool for managing environmental resources: Corvallis, Oregon, U.S. Environmental Protection Agency EPA/600/3-89/060, 152 p.
Omernik, J.M, 1995. "Ecoregions - a framework for environmental management", in Davis, W.S. and Simon, T.P., eds, Biological assessment and criteria - tools for water resource planning and decision making: Boca Raton, Florida, Lewis Publishers, p. 49-62.
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This page was last edited on 12/08/09