Regional Landscape Ecosystems of Michigan, Minnesota, and Wisconsin
SUBSECTION IV.1. Prairie du Chiens
DISCUSSION: Subsection is distinguished by the predominance of limestone and dolomite bedrock. Algific talus slope is restricted to this subsection, and relict white pine forests also occur here.
SUB-SUBSECTIONS: None.
ELEVATION: 603 to 1,450 feet (184 to 442 m).
AREA: 7,904 square miles (20,480 sq km).
STATES: Minnesota and Wisconsin.
CLIMATE: See section.
BEDROCK GEOLOGY: Large exposures of bedrock occur in the steep ravines. These exposures are primarily Ordovician dolomite, limestone, and sandstone in Minnesota; Cambrian sandstone, shale, and dolomite are exposed along the valley walls of the Mississippi River (Morey 1981, Morey et al. 1982, Sims et al. 1966). Devonian dolomite and limestone are more locally exposed along the western edge of the subsection, in Minnesota. In Wisconsin, Ordovician dolomites have the most exposures (Ostrom 1981).
LANDFORMS: See section.
LAKES AND STREAMS: Several major rivers flow through the subsection, forming steep ravines and, on some of the streams, broad alluvial plains. These rivers include the Mississippi, Wisconsin, Pecatonica, and the lower reaches of the Black and Chippewa; the Kickapoo forms the western boundary between Subsections IV.3.1 and IV.1.
SOILS: Prairie soils on the ridges; these are thick silt loams (loess) over cherty residuum over dolomite (Hole 1968, 1976; Hole and Germain 1994; Cummins and Grigal 1981). On some valley walls, soils are silt loam over sandstone. Soils are classified as Udalfs on ridges and fertile Udolls on valley floors (Anderson and Grigal 1984).
PRESETTLEMENT VEGETATION: Almost all the tallgrass prairie was restricted to this subsection; tallgrass prairie and bur oak savanna were the major vegetation types on ridge tops and dry upper slopes. Oak forest was common on moister slopes (Marschner 1974, Finley 1976, Lange 1990). Although the tallgrass prairies were restricted to the relatively narrow ridgetops, they often extended continuously for 30 or more miles along major stream divides. See section.
NATURAL DISTURBANCE: Fire was important on the upland prairie and oak-dominated ecosystems. Windthrows was probably more prevalent and important in the maple-basswood forest. Recent records of tornados and ice storms indicate that they had local impact on forest vegetation.
PRESENT VEGETATION AND LAND USE: The ridge tops and stream valleys are heavily used for agriculture; oak and hardwood forests persist on steep slopes.
RARE PLANT COMMUNITIES: Prairies, although once prevalent, are now rare. A rare natural community, algific talus slope, is found along the steep bluffs of tributaries of the Mississippi River. Relict pine forests are also common, especially at the southern edge of the subsection in Wisconsin.
RARE PLANTS: Minnesota only: Arenaria dawsonensis (rock sandwort), Carex davisii (Davis's sedge), Chrysosplenium iowense (golden saxifrage), Leersia lenticularis (catchfly grass), Melica nitens (three-flowered melic), Scutellaria ovata (ovate-leaved skullcap), Valeriana edulis (valerian). Wisconsin only: Aconitum noveboracense (northern monkshood), Agalinis gattingeri (round-stemmed false foxglove), Asplenium pinnatifidum (pinnatifid spleenwort), Commelina erecta var. deamiana (narrow-leaved dayflower), Dasistoma macrophylla (mullein foxglove), Eclipta alba (yerba de tajo), Lespedeza violacea (violet bush clover), Lespedeza virginica (slender bush clover), Myosotis laxa (small forget-me-not), Onosmodium hispidissimum (marbleseed), Parthenium integrifolium (wild quinine), Pellaea atropurpurea (purple cliff brake), Phegopteris hexagonoptera (broad beech fern), Polygala incarnata (pink milkwort), Psoralea esculenta (pomme-de-prairie), Rhamnus lanceolata var. glabrata (lance-leaved buckthorn), Triphora trianthophora (nodding pogonia), Silene virginica (fire pink). Minnesota and Wisconsin: Adoxa moschatellina (moschatel), Lesquerella ludoviciana (bladder pod), Napaea dioica (glade mallow), Orobanche uniflora (one-flowered broomrape).
RARE ANIMALS: Minnesota only: Hybopsis x-punctata (gravel chub), Moxostoma duquesnei (black redhorse). Wisconsin only: Wilsonia citrina (hooded warbler), Acris crepitans blanchardi (Blanchard's cricket frog), Elaphe obsoleta (rat snake), Libytheana bachmanii (snout butterfly), Gomphurus externus (plains clubtail (dragonfly)), Macromia taeniolata (royal river cruiser (dragonfly)), Stylurus plagiatus (russet-tipped clubtail (dragonfly)). Minnesota and Wisconsin: Crotalus horridus (timber rattlesnake).
 |
| Figure 16.—Subsection IV.1: Rush Creek Bluffs, Crawford County, Wisconsin. Bluff prairie occupies the dry south- and west-facing ridgetops within the Driftless Area. Moister slopes support forests of oak and maple-basswood, as well as oak savannas. Forests occupy the broad flood plain of the Mississippi River. Photo by E. Epstein. |
NATURAL AREAS: Wisconsin: State Natural Areas: Wyalusing Hardwood Forest, Brady's Bluff Prairie, Dewey Heights Prairie, Midway Railroad Prairie, New Observatory Woods, Tiffany Bottoms, Tower Hill Bottoms, Durst Rockshelter, Pine Hollow, Lodde's Mill Bluff, Avoca Prairie-Savanna, Blue River Sand Barrens, Five-Mile Bluff Prairie, Nelson-Trevino Bottoms, Honey Creek, Spring Green Reserve, Natural Bridge and Rockshelter, Trenton Bluff Prairie, Mazomanie Bottoms, Olson Oak Woods, Belmont Mound Woods, Rush Creek, Whitman Bottoms Floodplain Forest, Battle Bluff Prairie, Ipswich Prairie, Robinson Creek Pines, Cook Creek Cliffs, Rush River Delta, Morgan Coulee Prairie, Black Earth Prairie, Ferry Bluff, Wauzeka Bottoms, Eureka Maple Woods, Adiantum Woods, Arena Pines-Sand Barrens, Bakken's Pond, Mazomanie Oak Barrens, Richwood Bottoms, Smith Slough, Woodman Sand Prairie, Pecatonica River Woods, Gasner Hollow Prairie, Snow Bottom. Minnesota: State Natural Areas: Cannon River Turtle Preserve, Racine Prairie, Cannon Valley Trail.
PUBLIC LAND MANAGERS: See section. Minnesota: State Parks: Carley, Frontenac. State Forests: R.J. Dorer. Wildlife Management Areas: Gores.
CONSERVATION CONCERNS: See section.
BOUNDARIES: Boundaries are based on interpretation by Hole and Germain (1994) in Wisconsin and my interpretation of Morey et al. (1982) in Minnesota.
Previous Section -- Section IV. Driftless Area
Return to Contents
Next Section -- Subsection IV.2. Eau Claire
