|
|
|
|
Wetlands 101: How to Tell a Swamp from a Fenby Emily BergnerWetlands are an essential part of the natural environment. They provide habitat for an abundance of living creatures, control flooding, clean water, provide recreational opportunities for people, and are beautiful and interesting places to visit and admire. Many wetlands are adjacent to rivers and are necessary to the river's ecosystem, serving as breeding grounds for fish and habitat for young fish and other river creatures.In broad terms, wetlands are defined as transitional areas between dry land and bodies of water, such as lakes, rivers and streams. More specifically, they contain soils that are frequently wet, plant communities adapted to wet conditions, and have hydrology that is different from non-wetland areas. Individual wetlands can be quite unique, but can generally be grouped according to the source from which they receive water, their dominant vegetation, and their geologic and topographic characteristics. Perhaps the most familiar type of wetland is a floodplain, the flat, low area adjacent to many large rivers and streams. This area becomes flooded periodically when stream flows are high. Floodplains support a variety of plant species, and provide temporary storage for floodwaters and sediments from the river's watershed. Marshes are another common type of wetland. They occur along the shallow edges of lakes and rivers, and in poorly drained depressions in the landscape. They are dominated by floating leafed plants, and soft-stemmed aquatic plants. Most water in marshes comes from surface waters, but some ground water also enters marshes. Marshes are the wetlands with the greatest biodiversity, as well as the highest productivity, of all types of wetlands. There are a number of wetlands that, like marshes, support primarily herbaceous vegetation, but unlike marshes, derive water mostly from precipitation. These include wet meadows and wet prairies, grasslands with waterlogged soils and frequent standing water. Prairie potholes, which develop in the pockmarks left by glaciers, are found mainly in the Dakotas, Iowa, and the Canadian prairie, and may dry up during dry times. Playas are similar to Prairie Potholes, but are found in the southern High Plains of the United States, and occur in low areas. Finally, vernal pools are small, shallow ponds found in both grasslands and forests that are covered at the bottom by bedrock or hard clay, which hold in water. They often have water in the winter and spring, but may be dry in the summer and fall. Swamps are wetlands with woody plant life-trees, shrubs, or both. They are fed primarily by surface water inputs, have standing water for some of the year, and have very wet soils during the growing season. They often occur in floodplains. A final category of wetlands are bogs and fens, wetlands containing a spongy organic material called peat. Bogs are found in the formerly glaciated areas of the northern U.S., in the Southeast, and on mountains. They form in old lake basins or depressions in the landscape. As plants present in bogs die and sink, they form a layer of peat and gradually decompose. Bogs are often covered by a layer of sphagnum moss, which supports a mat of floating plants. They contain evergreen trees, shrubs, and herbaceous vegetation. The water in bogs derives mainly from rainfall, and its high acidity creates conditions for a unique community of species, including carnivorous plants such as the Venus flytrap. Fens, unlike bogs, derive their water from groundwater, and are less acidic than bogs or even basic, which allows them to support a wider variety of plants and animals. They are usually covered with grasses, sedges, reeds and wildflowers, and often look like meadows. They, too, contain a bottom layer of peat, and occur commonly in the same areas as bogs. Though different, all wetlands have an important part to play in the natural world. To learn more about current threats to wetlands in Illinois and what you can do, click here--- | |