Michigan's Rare Wetlands
The landscape of Michigan supports a wide variety of ecologically distinct wetland natural communities. At least 33 different types of wetlands occur in Michigan. In addition, many upland natural communities regularly support small, isolated wetlands such as vernal pools, or experience extended periods of inundation following snow melt or during years when precipitation is above normal. These wetlands provide critical habitat to a broad diversity of plants and animals, releasing clean water to lakes and streams, holding excessive floodwaters and preventing widespread flooding, facilitating groundwater recharge, and serving as a source for recreation, inspiration, and beauty.
Of the 33 distinct wetland types known to occur in Michigan, 26 are considered rare because fewer than 100 intact, functioning examples are known to occur (State Rank of S1, S2, and S3). Eight of the 26 rare wetland types are considered imperiled and at high risk of extinction because twenty or fewer intact and functioning examples are known (State Rank of S2). An additional three wetlands types are considered critically imperiled and at very high risk of extinction due to extreme rarity because five or fewer intact and functioning examples remain (State Rank of S1). The extent and abundance of these critically imperiled (S1) wetlands, which include Inland Salt Marsh, Lakeplain Wet-mesic Prairie, and Lakeplain Wet Prairie, have been drastically reduced due to exploitation, urban development, and agriculture in southern Lower Michigan.
Included in the 26 rare wetland natural communities are wetland types that may have always been uncommon because of their unique hydrology and physiography as well as types that have been significantly reduced as a result of human induced changes in the landscape, particularly in southern Lower Michigan. Historically uncommon wetland types include Inland Salt Marsh (S1), Coastal Plain Marsh (S2), Interdunal Wetland (S2), Patterned Fen (S2), Coastal Fen (S2), Prairie Fen (S3), Northern Fen (S3), Muskeg (S3), and Wooded Dune and Swale Complex (S3). Impacts to theses communities can be particularly devastating because of their natural rarity. Many other wetland communities were historically common but have since been drastically reduced in extent and abundance, especially in southern Lower Michigan. Examples of wetlands communities that were once common but now are very rare as a result of anthropogenic changes in the landscape include Lakeplain Wet Prairie (S1), Lakeplain Wet-mesic Prairie (S1), Wet Prairie (S2), Wet-mesic Prairie (S2), Wet-mesic Sand Prairie (S2), and Wet-mesic Flatwoods (S2).
In general, as a natural community becomes increasingly rare, the plants and animals it supports also become rare. This is especially true of the plants and animals that rely on the wet prairie communities for habitat. For example, together, the five wet prairie communities mentioned above provide habitat for 55 rare plant species and 47 rare animal species (Kost et al. 2007).
The wetlands that are naturally rare because of their unique hydrology and physiography also tend to support large numbers of rare species. For example, coastal plain marsh provides critical habitat for 43 rare plant species and 20 rare animal species, and prairie fen provides critical habitat for 20 rare plant species and 18 rare animal species (Kost et al. 2007).
Protecting rare wetlands not only serves to ensure that rare plants and animals have the habitat they need to survive but also enables these special places to serve society by releasing clean water to lakes and streams, preventing catastrophic floods, facilitating groundwater recharge, and providing a resource for recreation, inspiration, and scenic beauty.