Regional Landscape Ecosystems of Michigan, Minnesota, and Wisconsin
SUB-SUBSECTION V.2.2. Madison
DISCUSSION: Sub-subsection is defined on the basis of its dominant vegetation, bur oak openings (savannas) and oak forests. This vegetation occupies rolling to hilly outwash, drumlins on till plain, or end moraine with more fire protection than the flat to rolling sites occupied by tallgrass prairie, but less fire protection than sites occupied by sugar maple-basswood forest.
ELEVATION: 746 to 1,535 feet (227 to 468 m).
AREA: 3,982 square miles (10,320 sq km).
STATES: Wisconsin.
CLIMATE: See subsection.
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 and Ordovician dolomite with some limestone, sandstone, and shale (Ostrom 1981). Cambrian sandstone, with some dolomite and shale, is along the western edge of the sub-subsection.
LANDFORMS: Ground moraine predominates, often containing extensive drumlin fields. There are also numerous end moraines. Outwash features occur, often as narrow channels between drumlins.
LAKES AND STREAMS: Large lakes and streams are not common in those parts of the subsection dominated by oak savanna or forest.
SOILS: Soils 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. Under oak savannas and forests, forest soils (Typic hapludalfs) have developed (Hole and Germain 1994, Hole 1976).
PRESETTLEMENT VEGETATION: Savanna occupied rolling ground moraine (including the southwest-northeast-trending drumlins) or outwash without major fire barriers, such as streams, lakes, or wetlands. It also occurred on some steep end moraines, where soils were excessively drained and no major wetlands served as fire breaks. Oak forests are typically found on ground moraine with minor streams or wetlands forming fire breaks, or on relatively steep, dissected end moraine without major fire breaks.
Oak openings (savanna) were dominated by bur oak, and the oak forests were dominated by bur oak, white oak, and black oak. Marshes, wet meadows, and wet prairies were the major wetland types occupying the narrow drainageways and depressions within the oak savannas and forests; swamp forests were uncommon, probably because of the frequently occurring fires of the oak ecosystems.
NATURAL DISTURBANCE: Fire was important in maintaining oak savanna and forest. Native American land management may have contributed to the amount of fire occurring within this portion of Wisconsin; from 1810 to 1830 several Winnebago villages were along the Wisconsin River and on Lake Mendota and other lakes in Dane and Columbia Counties (Tanner 1986).
PRESENT VEGETATION AND LAND USE: The entire sub-subsection is intensively farmed. Forest persists primarily on steeper end moraines and in poorly drained depressions.
RARE PLANT COMMUNITIES: Oak openings (savannas), wet mesic prairie, wet prairie, and fens.
RARE PLANTS: Asclepias sullivantii (prairie milkweed), Aster furcatus (forked aster), Lespedeza leptostachya (prairie bush clover), Platanthera leucophaea (prairie white-fringed orchid), Solidago ohioensis (Ohio goldenrod).
RARE ANIMALS: Podiceps grisegena (red-necked grebe), Sterna forsteri (Forster's tern), Papaipema silphii (silphium borer moth).
NATURAL AREAS: State Natural Areas: Puchyan Prairie, Lost Lake, Waupun Park Maple Forest, Fountain Creek Wet Prairie, Muskego Park Hardwoods, Peat Lake, Fourmile Island Rookery, New Munster Bog Island, Gibraltar Rock, Karcher Springs, Silver Lake Bog, Waterloo Fen and Springs, Snapper Prairie, Faville Prairie, Bean Lake, Cherokee Marsh, Red Cedar Lake, Rocky Run Oak Savanna, Koro Prairie, Hook Lake Bog, South Waubesa Wetlands, Lulu Lake Fen, Cherry Lake Sedge Meadow, Parfrey's Glen, Bueleh Bog, Genesee Oak Opening and Fen, Pickerel Lake Fen, Berlin Fen, Lima Bog; The Nature Conservancy Preserves: Gromme Preserve (Rush Lake).
PUBLIC LAND MANAGERS: National Wildlife Refuges: Horicon.
CONSERVATION CONCERNS: Of the extensive original oak openings, only small preserves remain. The landscape is heavily disturbed and severely fragmented.
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