What are Wetlands?
Wetlands are unique ecosystems that often occur at the edge of aquatic (water, fresh to salty) or terrestrial (upland) systems. They may be wet year-round, wet during certain seasons, or wet during part of the day. Wetlands are areas where water covers the soil, or is present either at or near the surface of the soil all year or for varying periods of time during the year, including during the growing season.
Wetlands vary widely because of regional and local differences in soils, topography, climate, hydrology, water chemistry, vegetation, and other factors, including human disturbance. Indeed, wetlands are found from the tundra to the tropics and on every continent except Antarctica. Two general categories of wetlands are recognized: coastal or tidal wetlands and inland or non-tidal wetlands. In addition to bogs and swamps, wetlands include tidal marshes, prairie potholes, seagrass beds, forested wetlands, and seasonally ponded sites, such as vernal pools.
Why are they important?
The loss and degradation of wetlands in the U.S. has resulted in a decline in the important benefits that wetlands provide to society and the environment. Wetlands provide:
Support for birds and other wildlife. Wetlands support a wide diversity of birds. Eighty percent of America’s breeding bird population and more than 50 percent of the 800 species of protected migratory birds rely on wetlands. In addition to birds, other wildlife makes its home in wetlands, including reptiles, amphibians, muskrat, beaver, mink, raccoon, marsh and swamp rabbits, numerous mice, voles, shrews, lemmings, and other small mammals.
High biological productivity. Many wetlands are highly productive ecosystems in large part because they are rich in organic matter and nutrients. These nutrients support organisms within the marsh, but in many instances the nutrients are also transferred to nearby aquatic systems (lakes, rivers, and estuaries), enhancing the productivity of these systems and supporting human uses such as offshore commercial fisheries.
Biodiversity protection. Wetlands support a great diversity of species and many of the species are unique and rare. Among this vast diversity are many plant species used for food, drugs, and other commodities.
Good water quality. Wetlands are known for their ability to capture sediments and filter pollutants, which improves water quality. For example, spring floods often carry very turbid water which, if not for the filtering that occurs in downstream wetlands, could deposit sediment that would smother plants and fish eggs. In addition, wetlands constructed to treat municipal runoff require only a fraction of the construction and operation budget of a conventional system.