Regional Landscape Ecosystems of Michigan, Minnesota, and Wisconsin

DISCUSSION: This subsection has been subdivided into four sub-subsections, primarily on the basis of vegetation, with locally good correspondence of the dominant vegetation types to glacial landform and substrate. The treatment is based on that of Hole and Germain (1994), but many of their smaller map units have been eliminated. Delineation of sub-subsections on the basis of glacial landform and substrate alone was not successful at the scale of this map, although correlation of the vegetation to combinations of abiotic conditions would be possible at a more localized scale. The combination of a general lack of relief and the local heterogeneity of glacial landforms does not lend itself to regional mapping at this scale.

Sub-subsections: Milwaukee (V.2.1), Madison (V.2.2), Galena-Platteville (V.2.3), Kettle Moraine (V.2.4) (see figure 4).

ELEVATION: 580 to 1,535 feet (177 to 468 m).

AREA: 7,397 square miles (19,161 sq km).

STATES: Wisconsin.

CLIMATE: Growing season is 142 to 184 days (Hole and Germain 1994). Average annual precipitation is 32 to 34 inches, and average annual snowfall ranges from 36 inches in the south to approximately 44 inches in the north (Wendland et al. 1992). Extreme minimum temperature ranges from warmer than -30½F along Lake Michigan in the south to colder than -35½F inland and farther north (Reinke et al. 1993).

BEDROCK GEOLOGY: Drift over bedrock is generally less than 50 feet thick, except in the east where it is 100 to 200 feet thick (Trotta and Cotter 1973). The predominant bedrocks are Silurian dolomite to the east along Lake Michigan, and Ordovician dolomite in the central and western parts of the subsection (Ostrom 1981, Morey et al. 1982). Some limestone, sandstone, and shale are present in both of these bedrocks. Undifferentiated Devonian marine deposits are localized along the Lake Michigan shoreline. Cambrian sandstone, with some dolomite and shale, is along the far western edge of the subsection. Precambrian quartzite is localized in the west and Precambrian rhyolite, granite, and diorite are localized west of Lake Winnebago (Morey et al. 1982).

LANDFORMS: Till plain (ground moraine) is predominant; but there are also areas of dissected plain, end moraines, outwash deposits, lake plain, and ice-stagnation topography with many kettle lakes.

LAKES AND STREAMS: Large kettle lakes are concentrated within pitted outwash deposits and within or adjacent to end moraines. More linear lakes are within the ground moraine, trending in the same direction as the surrounding ground moraine features, but these are much less common. There are few major rivers in the subsection. The larger rivers include the Rock, Sugar, and a short segment of the Wisconsin.

SOILS: A silt-loam cap of loess covers the soils of most of the subsection, but there are also clay soils developed from glaciolacustrine deposits and sand soils developed from outwash deposits. Soils derived from the loess are silt loam at the surface, but subsoils are generally calcareous loam (till) or calcareous sand and gravel outwash (Hole and Germain 1994). The loess cap is typically about 2 feet thick.

PRESETTLEMENT VEGETATION: Bur oak openings (savannas), oak forest, and tallgrass prairie were predominant in the western part of the subsection, but sugar maple-basswood forest was common to the east where there is greater fire protection because of dissected topography and numerous kettle lakes. Even the trend of features such as drumlin ridges and adjacent wetlands have helped to determine the dominant vegetation within this subsection. On some southwest-northeast trending drumlin fields, tallgrass prairie and savanna were dominant; where north-south-trending drumlins served as fire barriers, sugar maple-basswood forests dominated.

NATURAL DISTURBANCE: Fire maintained the tallgrass prairies, oak savannas, and oak forests.

PRESENT VEGETATION AND LAND USE: Most of the subsection has been heavily developed for agriculture, except for Sub-subsection V.2.4, which occupies steep, irregular topography.

RARE PLANT COMMUNITIES: Tallgrass prairie and oak savanna are rare, even though both were originally dominant over large areas. Also fen, tamarack fen, wet prairie, and wet mesic prairie.

RARE PLANTS: Asclepias sullivantii (prairie milkweed), Aster furcatus (forked aster), Fimbristylis puberula (chestnut sedge), Lespedeza leptostachya (prairie bush clover), Platanthera leucophaea (prairie white-fringed orchid).

RARE ANIMALS: Oarisma poweshiek (Poweshiek skipper), Papaipema beeriana (liatris borer moth), Papaipema silphii (Silphium borer moth), Venustaconcha ellipsiformis ellipsiformis (Ellipse, a mussel), Podiceps grisegena (red-necked grebe), Sterna forsteri (Forster's tern).

NATURAL AREAS: State Natural Areas: Oshkosh-Larsen Trail Prairies, Puchyan Prairie, Ripon Prairie, Spruce Lake Bog, Oakfield Ledge, Waupun Park Maple Forest, Fountain Creek Wet Prairie, Fourmile Island Rookery, Mayville Ledge Beech-Maple Woods, Neda Mine, Gibraltar Rock, Audubon Goose Pond, Waterloo Fen and Springs, Snapper Prairie, Faville Prairie, Bean Lake, Cherokee Marsh, Westport Drumlin Prairie, Red Cedar Lake, Rocky Run Oak Savanna, Koro Prairie, Blue Spring Oak Opening, Hook Lake Bog, and South Waubesa Wetlands; The Nature Conservancy Preserves: Chiwaukee Prairie, Gromme Preserve (Rush Lake), Renak-Polak Woods.

PUBLIC LAND MANAGERS: National Wildlife Refuges: Horicon; State Forests: Kettle Moraine.

CONSERVATION CONCERNS: