When people hear the term wetland, they most commonly think of a marsh. Marsh is a term that represents a broad array of wetlands that are dominated by grass-like vegetation. Typical marsh plants include rushes, reeds, sedges, cattails, and grasses. They are wet areas which can be periodically covered by standing or slow-moving water and are usually associated with ponds, rivers, streams, inland lakes, and the Great Lakes. Although some marshes have sandy soils, marshes usually have finer textured, nutrient rich soils with a high content of organic matter.
There are many types of wetlands that are dominated by grass-like vegetation and fall into the general category of marsh. One that deserves special note occurs in swales between beach ridges, wind blown depressions, and small embayments along the Great Lakes shoreline. These wetlands (referred to as interdunal swale wetlands), depend on the Great Lakes for their water source. As such, their water table and period of saturation fluctuates with Great Lakes water levels. Because of the highly variable ecosystem characteristics, and the fact that they exist nowhere else on earth, interdunal swale wetland/upland complexes support many endangered or threatened species such as the Piping Plover, Pitcher's thistle, Lake Huron tansy, and Houghton's goldenrod. Due to a combination of the natural fragility of interdunal wetlands and the loss of shoreline habitat due to development along the Great Lakes shoreline, these habitats are threatened.
Another type of marsh-like wetland that deserves special note is the wet meadow. Wet meadows contain grass-like vegetation and saturated soils, but seldom have water standing on the ground surface. Many wet meadows occur in the former lake-plain of the Great Lakes, especially in southeast Michigan and the Saginaw Bay watershed. Because these areas are relics from a former geologic epoch, they provide habitat for many plant species rare in Michigan that are typically adapted to prairies. Unfortunately, a large percentage of these wet prairies (as they are sometimes called) have been severely degraded or converted to agriculture or housing.
Marshes comprise the most biologically productive ecosystems in Michigan. The lush vegetation and rich invertebrate and insect life provide excellent habitat and breeding grounds for water birds such as ducks, geese, swans, and herons. The common loon, bald eagle, and osprey also utilize marshes for feeding or nesting areas, as do numerous species of song birds. Marshes are also home to many mammals, such as muskrat and mink, and are important spawning grounds for many fish species.