Report Nr. 3342 Plant Colonization of Constructed Wetlands on a Michigan Clay Lake Plain

Road construction, housing, and other human developments often result in loss of wetlands and the benefits they provide. In an effort to mitigate the impacts of wetland destruction, developers can be required to create new wetlands. "Mitigation wetlands" have traditionally been designed by engineers. More recently, professional wildlife biologists have been invited to assist in designing wetlands to help assure products are functional and beneficial to wildlife. A primary characteristic used to measure success of wetland·loss mitigation projects is plant colonization of excavated sites. The presence of sustainable populations of aquatic plants indicates saturated soils and suggests that wetland functions are occurring. The purpose of this study was to document colonization of aquatic plants at wetlands constructed on a clay lake plain in eastern Upper Michigan. More specifically, researchers determined frequency of occurrence, stem density, and dominance (% coverage) of emergent and submergent plant species found at wetlands three to five years after construction. Also provided within this report are wetland construction recommendations for clay soils with reference to cost differences.