Regional Landscape Ecosystems of Michigan, Minnesota, and Wisconsin
SUBSECTION II.2. Coteau des Prairies
DISCUSSION: The coteau is typified by highly dissected, loess-covered till plains that are Illinoian, pre-Illinoian, and late Wisconsinan in age (Lehr and Gilbertson 1988). These were originally covered with tallgrass and midgrass (mixed grass) prairie. The outer edges of the coteau are non-dissected, non-loess-covered late Wisconsinan (Des Moines lobe) end and ground moraines.
Sub-subsections: The Inner Coteau des Prairies (II.2.1) consists of highly dissected moraines of pre-Wisconsinan drift, capped by thick loess deposits. The Lake Benton-Adrien Coteau (II.2.2) is a landscape of rolling moraine ridges of late Wisconsinan drift mantled with loess 1 to 3 feet thick. The Ivanhoe-Worthington Coteau (II.2.3), a series of terminal and end moraines separated by ground moraines, ranges from gently undulating to steeply rolling and hilly
(Hargrave 1992). Its northeastern edge is a steep escarpment, with the Minnesota lowlands to the northeast, cut by several streams occupying narrow, straight ravines. (See figure 3.)
ELEVATION: 1,140 to 1,995 feet (347 to 608 m).
AREA: 4,275 square miles (11,073 sq km).
STATES: Minnesota.
CLIMATE: Annual precipitation ranges from 24 inches in the west to 27 inches in the east; 11 to 12 inches arrive during the growing season (Hargrave 1992). Average growing season is 145 to 150 days.
BEDROCK GEOLOGY: Glacial drift is as thick as 800 feet, but there are exposures of bedrock at the southwestern edge of the section in Rock and Pipestone Counties (Olsen and Mossler 1982). A massive outcrop of red upper Precambrian quartzite is located in those counties (Wright 1972, Morey 1976, Olsen and Mossler 1982).
LANDFORMS: The coteau contains areas typified by several landforms, including highly dissected, loess-covered till plains that are Illinoian, pre-Illinoian, and late Wisconsinan in age (Lehr and Gilbertson 1988), and non-dissected, non-loess-covered late Wisconsinan (Des Moines lobe) end and ground moraines.
LAKES AND STREAMS: See sub-subsections.
SOILS: Soils are primarily Mollisols (primarily Aquolls and Udolls, some Borolls and Ustolls). Cummins and Grigal (1981) map both dry prairie and moist prairie soils; most of the dry prairie soils occur on dissected or eroded topography, and moister prairie soils occur on rolling end moraines with variable local relief.
PRESETTLEMENT VEGETATION: Tallgrass prairie covered almost the entire landscape; wet prairies covered much less of the landscape than in Subsections I.1 and II.1 (Marschner 1974). Wet prairie was restricted to narrow stream margins in much of the subsection. Forest was similarly restricted to ravines along a few streams, such as the Rock and Redwood Rivers.
The prairies were drier in this subsection than in Subsection II.1, accounting for the prevalence of prairie plants characteristic of midgrass prairies further to the west.
NATURAL DISTURBANCE: Fire and drought maintained the prairie.
PRESENT VEGETATION AND LAND USE: The highest density of upland prairie plants on the coteau is in this subsection, according to Wheeler et al. (1992b).
RARE PLANT COMMUNITIES: Although prairie vegetation originally dominated the entire subsection, all prairie types are now rare, including calcareous seepage fen, dry prairie (hill subtype), dry prairie (sand-gravel subtype), glacial till hill prairie, mesic prairie, mesic prairie (crystalline bedrock subtype), and wet prairie. Maple-basswood forest is also locally present.
RARE PLANTS: Asclepias sullivantii (Sullivant's milkweed), Heteranthera limosa (mud plantain), Isoetes melanopoda (quillwort sp.), Lespedeza leptostachya (prairie bush clover), Plantago elongata (slender plantain), Platanthera praeclara (western prairie fringed orchid), Rhynchospora capillacea (hair-like beak-rush).
RARE ANIMALS: Birds: Athene cunicularia (burrowing owl), Bartramia longicauda (upland sandpiper), Calcarius ornatus (chestnut-collared longspur), Lanius ludovicianus (loggerhead shrike); Fish: Notropis topeka (Topeka shiner); Reptiles: Emydoidea blandingii (Blanding's turtle); Insects: Hesperia dacotae (Dakota skipper), Hesperia ottoe (Ottoe skipper), Oarisma powesheik (Powesheik skipper).
NATURAL AREAS: State Natural Areas: Compass Prairie, Prairie Bush Clover, Prairie Coteau; Others: Blue Gentian Prairie, Glynn Prairie, Hole-in-the-Mountain Prairie, Lundbland Prairie, Split Rock Creek Recreation Area.
PUBLIC LAND MANAGERS: Wildlife Management Areas: Altona, Badger Lake, Burke, Carlson, Casey Jones, Coon Creek, Expandere, Hole-in-the-Mountain, Penthole, Pipestone, Prairie Marshes, Salt and Pepper Creek, Sangl, Sherwood, Sioux Nation, Talcot Lake; Waterfowl Production Areas: Des Moines River, Spirit Lake; State Parks: Blue Mounds, Camden, Kilen Woods, Lake Stetek; Others: Garvin County Park, Hole-in-the-Mountain County Park, Sunrise County Park.
CONSERVATION CONCERNS:
Previous Section -- Subsection II.1. Upper Minnesota River Country
Return to Contents
Next Section -- Sub-subsection II.2.1. Inner Coteau des Prairies
