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Woody wetlands, or forested wetlands, are wetlands where the dominant vegetation consists of trees or shrubs. Forested wetlands in the project area include southern swamps, floodplain forests and southern shrub-carr. Historically, forested wetlands were common within the project area prior to the extensive logging of the nineteenth century. The flat, poorly drained soils, the thick clay layer underlying a thin layer of sand or loam and a high water table resulted in an abundance of lowland hardwood forest throughout the lakeplain.
Floodplain forests are among the most diverse plant communities in the state. The processes of flooding, bank cutting and sediment deposition result in characteristic land forms; sandbars and mudflats, levees or ridges along the water where coarser sediments are deposited and terraces behind the levees. In spring, cool air settles in the low river valleys where the water warms up slowly and as a result the trees do not leaf out until much later than higher areas nearby. Because of this, they are a refuge for more southern species which would suffer frost damage on the adjacent uplands, where temperatures rise earlier in spring but late frosts are common. Later in summer the floodplains are hotter and more humid than the uplands nearby. Southern species which reach their northern limit in Michigan's southern floodplain forest and Ontario's Carolinian Forest include honey locust, Ohio buckeye, paw-paw, redbud, blue ash, Kentucky coffee-tree, sycamore and hackberry.
Southern swamps are forested wetlands in isolated low areas with high water tables. Because they are not adjacent to rivers or streams, they do not experience flooding, although they may experience saturated soils and standing water in spring. Within the project area, they occur on low lying clay soils on the glacial lakeplain. Moisture and nutrients are generally available throughout the year but oxygen levels are low and the plants found there are adapted to these conditions. Swamps tend to have a high proportion of organic materials in their soils.
Rare plants found in forested wetlands include cup-plant, Virginia water horehound, false hop sedge, red mulberry, pumpkin ash, Shumard oak, showy orchis and wahoo. The cerulean warbler, Louisiana water thrush, Indiana bat and red-shouldered hawk are also found here.
For more information, see: Coastal Habitat Assessment, Section IV (PDF)