Regional Landscape Ecosystems of Michigan, Minnesota, and Wisconsin
SUB-SUBSECTION IX.6.2. Ewen
DISCUSSION: In Michigan, a relatively small area of older glacial lake plain created by Glacial Lake Ontonagon (Leverett 1929) extends about 25 miles further inland than the lake plain of Subsection IX.8. This lake bed is deeply dissected by several rivers and is separated from Subsection IX.8 by a narrow band of steep volcanic bedrock ridges.
ELEVATION: 700 to 1,350 feet (213 to 411 m).
AREA: 482 square miles (1,249 sq km).
STATES: Michigan.
CLIMATE: Growing season is 110 to 120 days (Eichenlaub et al. 1990). Extreme minimum temperature ranges from -44½F near Lake Superior to -48½F farther inland. Average annual precipitation ranges from 34 to 36 inches. Average annual snowfall is 120 to 180 inches, with heavier amounts closer to the Lake Superior shoreline.
BEDROCK GEOLOGY: Bedrock is not exposed at the surface except in localized outcrops along streams. Bedrock consists of Keweenawan-age Precambrian sedimentary bedrock, primarily sandstone, shale, and conglomerates. The shales are locally copper-rich.
LANDFORMS: A relatively small area of older glacial lake plain that extends about 35 miles inland. This lake bed is deeply dissected by several rivers.
At the east edge of the sub-subsection, there are some small sand dunes, distinct from the rest of the clay lake plain. Also at the southeast is an area of flat, poorly drained lake plain. The dunes were originally dominated by forests of white and red pine, which have been replaced largely by bigtooth aspen after logging and post-logging fires. The poorly drained lake plain remains dominated by swamp forest, but there are no data to detail its composition.
LAKES AND STREAMS: The lake plain contains no lakes. Several rivers cut deep ravines, 100 feet deep or more, into the clay soils. Rivers include the South, East, and Middle Branches of the Ontonagon River, and the Baltimore, Firesteel, and Flintsteel Rivers.
SOILS: Primarily lacustrine clays, with some dune sands at the eastern margin.
PRESETTLEMENT VEGETATION: The vegetation of the clay lake plain cannot be easily characterized; drainage conditions varied greatly over small distances on the dissected clay plain, and with these changes came major vegetation changes (Albert 1990, Comer et al. 1993a). Flat headwater areas supported a diverse mix of balsam poplar, northern white-cedar, eastern hemlock, white spruce, trembling aspen, and yellow birch. Locally there were also almost pure stands of hemlock and white pine in some flat stream headwaters. Alder formed dense, streamside thickets. On well-drained ridge tops, northern hardwood forests of sugar maple, hemlock, yellow birch, and basswood were locally common.
The dunes in the east were originally dominated by forests of white and red pine.
NATURAL DISTURBANCE: No disturbances noted.
PRESENT VEGETATION AND LAND USE: The upland ridge tops were grazed; almost no examples of original vegetation persist. Pine was harvested for mining timbers. White pine and red pine on the small sand dunes have been replaced largely by bigtooth aspen after logging and post-logging fires.
RARE PLANT COMMUNITIES: None identified to date.
RARE PLANTS: Carex assiniboinensis (assiniboia sedge).
RARE ANIMALS: None identified to date.
NATURAL AREAS: None.
PUBLIC LAND MANAGERS: Ottawa National Forest.
CONSERVATION CONCERNS: The dissected topography along streams contains many seepage areas of botanical interest, but only preliminary investigations have been done.
BOUNDARIES: This sub-subsection is part of the Ottawa National Forest, which has done more detailed ECS mapping.
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