Regional Landscape Ecosystems of Michigan, Minnesota, and Wisconsin
SUB-SUBSECTION VI.1.3. Jackson Interlobate
DISCUSSION: Sub-subsection VI.1.3 is the northern portion of an interlobate area between three glacial lobes, which formed approximately 13,000 to 16,000 years B.P. The interlobate is more than 150 miles long. This sub-subsection consists of most of the northeastern two-thirds of the interlobate, which is characterized by relatively steep end-moraine ridges surrounded by pitted outwash deposits; kettle lakes and wetlands are common within the outwash.
ELEVATION: 750 to 1,280 feet (229 to 390 m).
AREA: 2,581 square miles (6,689 sq km).
CLIMATE: Growing season is 140 to 150 days, generally decreasing to the north (Eichenlaub et al. 1990). Danger of late spring frosts is great due to numerous lowland depressions (outwash and kettle lakes). Average snowfall is 40 to 50 inches; greatest amounts are in the extreme north and extreme south. Annual precipitation is 30 to 32 inches, with highest amounts in the south. Extreme minimum temperature ranges from -22½F to -28½F, with coldest values in the north.
BEDROCK GEOLOGY: The underlying Mississippian and Pennsylvanian bedrock, primarily sandstone (Dorr and Eschman 1984, Milstein 1987), is locally exposed at the surface in Jackson and Hillsdale Counties at the southwestern end of the sub-subsection (Akers 1938). Drift thickness is generally less than 100 feet in both of these counties. In the northeastern part, bedrock is overlain by 250 to 300 feet of glacial drift.
LANDFORMS: Sub-subsection contains broad expanses of outwash sands that surround sandy and gravelly end moraines and ground moraines. End and ground moraines remain as islandlike hills surrounded by flat outwash. Large linear segments of end moraine, broken only by narrow outwash channels, are typically located along the margins of the sub-subsection.
Sub-subsection VI.1.3 also includes areas of icecontact topography. Kettle lakes, kames, eskers, and segments of outwash channel are the predominant features of the icecontact areas. At the west edge of the sub-subsection, the topography is more gentle; broad, coarsetextured ridges are surrounded by deposits of outwash sand.
Both on the outwash channels and on the groundmoraine ridges, slopes are generally in the 0 to 6 percent class; on the endmoraine and icecontact ridges, slopes can be as steep as 25 to 40 percent. Most of the small segments of end moraine surrounded by outwash have slopes predominantly in the 0 to 6 percent and 6 to 12 percent classes. The large blocks of end moraine at the margins of the sub-subsection commonly have steeper slopes in the 12 to 25 percent or 25 to 40 percent classes.
LAKES AND STREAMS: Many kettle lakes and ponds on the pitted outwash, end moraines, and ice-contact topography. Extensive wetlands surround many of the lakes and occupy entire ice-block depressions. Both marl and peat deposits were extensively mined in the past.
The headwaters of many major rivers originate in the extensive wetlands of the sub-subsection. These include the Huron, Grand, Kalamazoo, and St. Joseph Rivers.
SOILS: The soils of the moraines are typically well and excessively well drained. Drainage conditions on the outwash are more variable, ranging from excessively well drained to very poorly drained. Thick outwash deposits are usually characterized by excessively well drained conditions. Shallow outwash deposits are underlain in some places by bedrock or finetextured till and lacustrine deposits, causing poor or very poor drainage conditions. On icecontact topography, soils are typically excessively drained on the upland kames and eskers and poorly or very poorly drained in the kettles and outwash channels. Where the topography is steep, organic soils can be 10 to 15 feet deep in narrow outwash channels.
Soil textures range from sand to clay; the most common soil texture is sandy loam on the moraine ridges and sand on the outwash plains. The circumneutral glacial drift that forms the moraines is largely derived from the local limestone bedrock. Illuviation is responsible for the formation of a clayrich (argillic) horizon in many of the soils on moraines, providing better waterholding capacity than many of the outwash soils. In the icecontact areas, soils are sands and gravels. The Soil Conservation Service (1967) classifies the soils of the sub-subsection as Hapludalfs with Argiudolls.
PRESETTLEMENT VEGETATION: Vegetation reflects underlying differences in landform and topography. On the sandy moraines, open savannas of black oak, white oak, and hickory were common. GLO surveyors described the open oak forests as "barrens," "oak openings," "barren and scrubby timber," or "scattered timber." Chapman (1984) cites several references linking the open stand conditions to frequent burning by Native Americans. Savanna and prairie were absent or uncommon on the steeper endmoraine blocks at the margins of the sub-subsection, but bur oak savannas were located on the smaller "islands" of gently sloping ground moraine and end moraine at the western edge of the sub-subsection. Other dominants of the oak savannas were white oak, black oak, and chinquapin oak.
Most of the wetlands on the end moraines were shrub or tree swamps located in lower slope position or in small depressions. Wetlands on the lower slopes were typically hardwood swamps. Kettle lakes and swampy depressions on the moraines typically supported shrub swamp, hardwood swamp, or tamarack swamp.
The outwash channels supported large wetlands of several types. At the margins between the uplands and the outwash, calcareous seepages often supported fens. Tamarack grew near the upland margins of the fens. Grass and sedge meadows were found growing adjacent to streams on large areas of the outwash channels.
Swamp forests were most common along margins of major streams on the outwash. Tamarack was common along lake edges and in kettles or depressions in the outwash.
On droughty ice-contact topography, black oak (probably including some northern pin oak) was commonly the dominant forest species. White oak and hickory were also common on slightly moister icecontact sites, and red oak occupied moist foot slopes.
In areas of ice-contact topography, wetlands were commonly restricted to narrow belts surrounding kettle lakes. These consisted of shrub, hardwood, or conifer swamps. Kettles were sometimes completely occupied by either swamp or bog vegetation.
NATURAL DISTURBANCE: According to recent accounts, lightning fires occasionally occur in both uplands and wetlands within the sub-subsection. In the GLO notes, there were isolated mentions of fires resulting from Native-American activities, as well as numerous historic references to Native-American fires in the oak savannas or barrens of the sub-subsection.
PRESENT VEGETATION AND LAND USE: Most of the uplands have been farmed, except the steepest end moraines and ice-contact ridges, which have been maintained as woodlots or are now either recreational or wildlife management areas. Many of these steep ridges have been pastured in the past. Oak savannas either have been converted to farm land or have grown into closedcanopy oak forests due to fire suppression.
Both agricultural lands and the steeper forested lands are now being rapidly converted to residential developments, especially near metropolitan Detroit. Both residential development and agricultural land use have resulted in rapid eutrophication of lakes and degradation of many wetlands. Road construction and ditching have also modified the hydrology of many wetlands.
RARE PLANT COMMUNITIES: Oak savannas, once prevalent on large parts of the landscape, have been destroyed by agriculture or degraded by fire exclusion.
RARE PLANTS: Baptisia lactea (prairie false indigo), Baptisia leucophaea (cream wild indigo), Cacalia plantaginea (prairie Indian-plantain), Celtis tenuifolia (dwarf hackberry), Cypripedium candidum (white lady's-slipper), Eleocharis caribaea (spike-rush), Eryngium yuccifolium (rattlesnake-master), Eupatorium sessilifolium (upland boneset), Filipendula rubra (queen of the prairie), Gentiana puberulenta (downy gentian), Muhlenbergia richardsonis (mat muhly), Sporobolus heterolepis (prairie dropseed), Valeriana ciliata (edible valerian).
RARE ANIMALS: Ammocrypta pellucida (eastern sand darter), Ammodramus henslowii (Henslow's sparrow), Cryptotis parva (least shrew), Dendroica discolor (prairie warbler), Dendroica cerulea (cerulean warbler), Nerodia erythrogaster neglecta (copperbelly water snake), Neonympha mitchelli mitchelli (Mitchell's satyr), Oarisma poweshiek (Poweshiek skipper), Oecanthus laricis (tamarack tree cricket), Papaipema beeriana (blazing star borer), Sistrurus catenatus catenatus (eastern massasauga rattlesnake), Tachopteryx thoreyi (greyback).
NATURAL AREAS: State Natural Areas: Haven Hill; Michigan Nature Association Preserves: Goose Creek Grasslands, Lakeville Swamp, Lefglen, Dwarf Hackberry Trees, Timberland Swamp, Burr Memorial Prairie, Haehnle Memorial, Sand Prairie, Harvey N. Ott; The Nature Conservancy Preserves: Sharon Hollow, Jonathan Woods; Other: George Reserve, Seven Ponds Nature Center, Park Lyndon, Whitehouse Nature Center, Columbia Nature Sanctuary.
PUBLIC LAND MANAGERS: State Game Areas: Onsted, Gregory, Sharonville, Somerset; State Recreation Areas: Waterloo, Highland, Bald Mountain, Pinckney, Holly, Island Lake, Proud Lake, Pontiac Lake, Brighton, Ortonville, Metamora-Hadley; State Parks: Hayes; State Wildlife Areas: Unadilla; Metroparks: Indian Springs, Kensington, Stony Creek; County Parks: Park Lyndon, Independence Oaks.
CONSERVATION CONCERNS: Urban and residential development is destroying many of the lakes and wetlands of the sub-subsection, especially northwest of Detroit. Upland forests, important for wildlife habitat and migration corridors, are also being rapidly fragmented by residential developments.
BOUNDARIES: Sub-subsection VI.1.3 has physiography and soils similar to Sub-subsection VI.5.2, but has a longer growing season (Albert et al. 1986).