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WETLAND TYPES

1. VERNAL POND
Vernal ponds are small bodies of standing water that form in the spring from meltwater and are often dry by mid-summer or may even be dry before the end of the spring growing season. Many vernal ponds occur in depressions in agricultural areas, but may also be found in woodlots. Wetland vegetation may become established but are usually dominated by annuals.


2. WET MEADOW
Wet meadows usually look much like a fallow field except that they are dominated by waterloving grasses and sedges. They will contain nearly 100% vegetative cover with very little or no open water. Any surface water present is temporary or seasonal and only during the growing season in the spring. Wet meadows often form a transition zone between aquatic communities and uplands with soils that are often saturated and mucky.


3. BOG
Bogs are acidic and nutrient-poor wetlands fed only by precipitation. They are found on saturated, peat soils that may accumulate to 6 meters deep. They support low shrubs, herbs and a few tree species on a mat of sphagnum moss. Some bogs, termed ‘conifer bogs’ may be totally grown over with no open water, and are dominated by conifers such as tamarack and black spruce. Other bogs, termed ‘open bogs’ consist of open water surrounded by floating vegetation. Acid-tolerant plants found in and around bogs include labrador tea, bog rosemary, myrica (sweet) gale, and sphagnum moss. Many species of orchids prefer bog habitats, as do insect-eating sundews and pitcher plants. Bogs are usually found only in the northern part of Michigan.

4. MARSH
Marshes are the most dynamic and productive of all interior wetland types. They are flooded regularly by standing or slowly moving water---typically, they have standing water from 1 inch to 3 feet deep. The amount of water can fluctuate seasonally or from year to year. They are dominated by soft-stemmed emergent plants such as cattails, bulrushes, or sedges. Vegetative cover is usually around 50%. In Michigan, marshes can be found at the edge of some rivers and lakes, in lowlands and depressions, and in swales between sand dunes.


5. SWAMP
Swamps are dominated by woody plants---shrubs and/or trees. The soil is saturated throughout the growing season by surface or underground water through rich mineral soils. During the dry season (summer months), the water table drops low enough to aerate the upper layer of soil, allowing cottonwood, water birch, willow and other plants to survive. In Michigan, trees and shrubs found in swamps include red and silver maple, cedar, balsam, willow, alder, black ash, elm and dogwood. They often occur along streams, in floodplains, or in shallow lake basins.


6. FEN
Fens differ from bogs in that they receive inflows of surface and groundwater, resulting in more nutrient-rich and less acidic environment. Sedges typically blanket the fen’s surface, along with other grasses and shrubs. Fens have a higher plant diversity than bogs due to higher nutrient levels.

7. POND or OPEN WATER
Ponds are open bodies of water less than 20 acres in size and that do not dry up during summer months. There is little emergent vegetation but some floating vegetation may occur around the edges.

Sources: Understanding Wetlands by Ducks Unlimited Canada;
Michigan Dept of Natural Resources Wildlife Division - Frog & Toad Survey

 


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Last Update: May28, 2003

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