Regional Landscape Ecosystems of Michigan, Minnesota, and Wisconsin
SUB-SUBSECTION IX.3.3. Central Wisconsin Loess Plains
DISCUSSION: Sub-subsection IX.3.3 is an undulating to nearly level plain; rolling topography accounts for about one-fifth of the land area (Hole and Germain 1994). Lakes are much less common here than in the other three sub-subsections.
ELEVATION: 1,082 to 1,673 feet (330 to 510 m).
AREA: 3,981 square miles (10,315 sq km).
STATES: Wisconsin.
CLIMATE: Continental, with moderately heavy snows and extremely cold winters. See subsection.
BEDROCK GEOLOGY: Precambrian bedrock is generally less than 50 feet below the surface in the south and from 50 to 300 feet below the surface in the north. Bedrock includes gneiss, amphibolite, mafic metavolcanic rock, rhyolite, granite, and diorite (Morey et al. 1982). The underlying bedrock forms an undulating plain with scattered bedrock-cored ridges (Hole and Germain 1994). Basalts (Precambrian) and Cambrian sandstone are present to the west in Polk, Barron, and Washburn Counties.
LANDFORMS: Ground moraine with southwest-trending drumlins characterizes the uplands. There are smaller inclusions of stagnation moraine and end moraine. Narrow, poorly drained outwash channels are numerous.
LAKES AND STREAMS: Almost no large lakes on this ground moraine; many peatlands; many small creeks and rivers. Most of the rivers flow to the southwest, including the Brunet, Thornapple, Flambeau, and Jump. In the northeast, two rivers flow to the southeast, the Somo and Spirit. Peatlands are concentrated to the north in Ashland and Price Counties; wetlands are smaller and much less common farther to the south, where the streams are parallel and closely spaced.
SOILS: Acid silt loams, podzolized, rocky, and often poorly drained (Hole 1976, Hole and Germain 1994). As much as 30 inches of wind-blown silt cover the underlying acidic, reddish sandy loam till. Sandy and stony material of the till has been worked into the overlying loess by windthrow, animal digging, and frost action. The loess cap is less continuous in the western portion (Polk, Washburn, and Barron Counties). Spodozols are more distinct, and the amount of clay in the B horizon is less than in the soils found on the till plain in Sub-subsection IX.4.1 to the south (my interpretation of Hole 1976). The reduced amount of clay may be related to a shorter period of time for soil development (Hole 1976); but based on soils sampled just to the north in Michigan (Albert 1983, 1990; Spies 1983), it may also be related to the low amount of clay-forming minerals in the parent material.
PRESETTLEMENT VEGETATION: The original vegetation was largely mesic northern forests of hemlock, sugar maple, and yellow birch, with white pine and red pine (Finley 1976). Forested wetlands occupied about 25 to 50 percent of the sub-subsection in Ashland and Price Counties to the north. Common dominants included northern white-cedar, black ash, balsam fir, and tamarack. In the west (Polk, Barron, and Washburn Counties), there is no hemlock in the forests and wetlands are much less common and less extensive.
NATURAL DISTURBANCE: Windthrow, the predominant disturbance, was common in both the east and west parts of the sub-subsection (Canham and Loucks 1984).
PRESENT VEGETATION AND LAND USE: The primary land use is for forest products. The silt-loam soils are also used for dairy farming and locally for crops, in contrast to nearby sandier soils, which are managed as forest or pasture (Hole 1976). Rockiness, poor drainage, and relatively steep, small upland features restrict agriculture.
RARE PLANT COMMUNITIES: None identified to date.
RARE PLANTS: None identified to date.
RARE ANIMALS: None identified to date.
NATURAL AREAS: State Natural Areas: Flambeau River Hardwood Forest, Lake of the Pines Conifer-Hardwoods, Plagge Woods, Tula Lake.
PUBLIC LAND MANAGERS: Chequamegon National Forest.
CONSERVATION CONCERNS: Relatively few areas are protected as natural areas. Forest management for hardwoods is intensive, with short rotation time, due to the high productivity on the silt-loam soils. Conflicts between forest management goals and biodiversity goals might be expected to be greater here than in the remainder of the subsection.
BOUNDARIES: See comments under the BOUNDARIES section of Sub-subsection IX.3.2. Small areas of end moraine along the boundary between Sub-subsection IX.3.3 and Subsection IX.5 have not been mapped at this scale. The Chequamegon National Forest maps this end moraine as part of Sub-subsection IX.3.2; but I felt that the mosaic of end moraine, ground moraine, and outwash in Iron, Price, and Oneida Counties was better treated at the more local LTA level. See the Chequamegon National Forest's ECS classification.
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