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ELEVATION: 885 to 1,300 feet (270 to 396 m).

AREA: 699 square miles (1,810 sq km).

STATES: Wisconsin.

CLIMATE: See subsection. The wet depressions are the most frost-prone part of Subsection V.1.

BEDROCK GEOLOGY: Underlying bedrock is predominantly Cambrian sandstone, but Precambrian-age (Archean) gneiss and amphibolite occur at the northern edge of the sub-subsection (Morey et al. 1982). See subsection.

LANDFORMS: A broad expanse of sand lake plain, part of Glacial Lake Wisconsin.

LAKES AND STREAMS: No natural lakes. Numerous small streams flow across the sub-subsection into the Wisconsin River.

SOILS: Soils are primarily formed on sand; they include poorly drained mineral soils (Humaquepts and Aquic Udipsamments) and organic soils, both muck and peat (Histosols) (Hole 1976, Hole and Germain 1994). There are also small inclusions of lacustrine clays.

PRESETTLEMENT VEGETATION: On the lake plain, moving from west to east, there was first a broad zone of conifer-dominated swamp forest, then a several-mile-wide zone of marsh and sedge meadow. Tamarack was dominant along the edges of the poorly drained lake basin, while black spruce dominated the center of the basin (Finley 1976). Northern white-cedar was absent. The marshes and sedge meadows were the most extensive in the State. Dominant grasses included blue joint grass and cordgrass (Hole and Germain 1994). White pine-red pine forest occurred on slightly better drained sandy sites.

NATURAL DISTURBANCE: Both fire and seasonal flooding were important for maintaining the marshes and wet meadows, and fire was probably equally important in the conifer swamps and pine forests.

PRESENT VEGETATION AND LAND USE: Most of the poorly drained lake plain remains dominated by vegetation similar to the original vegetation.

RARE PLANT COMMUNITIES: Coastal plain marsh and pine barrens.

RARE PLANTS: Bartonia virginica (screwstem), Myriophyllum farwellii (Farwell's water-milfoil), Polygala cruciata (cross milkwort), Rhexia virginica (Virginia meadow beauty).

RARE ANIMALS: Erynnis persius persius (Persius dusky wing), Incisalia irus (frosted elfin), Lycaeides melissa samuelis (Karner blue), Ophisaurus attenuatus (western slender glass lizzard), Pedioecetes phasianellus (sharp-tailed grouse), Sistrurus catenatus (eastern massasauga rattlesnake).

Figure 18.—Sub-subsection V.1.2: Brockway Ponds, Jackson County, Wisconsin. The flat lake-plain landscape is largely poorly drained, containing extensive wetlands dominated by sedges, and small ponds with disjunct plant species from the Atlantic Coastal Plain. The sandy uplands support dense forests of jack pine; before fire-control, these forests burnt regularly and were described as open barrens. A recent jack-pine budworm infestation has resulted in high mortality of jack pine on this site. Photo by Eric Epstein.

NATURAL AREAS: State Natural Areas: Necedah Oak-Pine Savanna, Necedah Oak-Pine Forest.

PUBLIC LAND MANAGERS:

CONSERVATION CONCERNS: Natural vegetation is affected by fire exclusion, continued alteration of wetlands through ditching/diking, and expansion of the cranberry industry.