wetland

Florida's Everglades, the largest wetland system in the United States.^[1]

This article contains general information pertaining to all wetlands. For more details, see the specific wetland types, such as bog, marsh, and swamp. For Charlotte Roche's novel see Feuchtgebiete.

A wetland is an area of land whose soil is saturated with moisture either permanently or seasonally. Such areas may also be covered partially or completely by shallow pools of water.^[2] Wetlands include swamps, marshes, and bogs, among others. The water found in wetlands can be saltwater, freshwater, or brackish.

Wetlands are considered the most biologically diverse of all ecosystems. Plant life found in wetlands includes mangrove, water lilies, cattails, sedges, tamarack, black spruce, cypress, gum, and many others. Animal life includes many different amphibians, reptiles, birds, and furbearers.^[3]

In many locations, such as the United Kingdom, Iraq, South Africa and the United States, wetlands are the subject of conservation efforts and Biodiversity Action Plans.

Technical definitions

Wetlands have been categorized both as biomes and ecosystems.^[3] They are generally distinguished from other water bodies or landforms based on their water level and on the types of plants that thrive within them. Specifically, wetlands are characterized as having a water table that stands at or near the land surface for a long enough season each year to support aquatic plants.^[3][4][5] Put simply, wetlands are lands made up of hydric soil.

Wetlands have also been described as ecotones, providing a transition between dry land and water bodies.^[6] Mitsch and Gosselink write that wetlands exist "...at the interface between truly terrestrial ecosystems and aquatic systems, making them inherently different from each other, yet highly dependent on both."^[7]

Under the Ramsar Convention:

• Article 1.1: "...wetlands are areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed six metres."

• Article 2.1: "[Wetlands] may incorporate riparian and coastal zones adjacent to the wetlands, and islands or bodies of marine water deeper than six metres at low tide lying within the wetlands".

Conservation

Due to their lack of potential financial benefits, wetlands have historically been the victim of large-scale draining efforts for real estate development, or flooding for use as recreational lakes. Wetlands provide a valuable flood control function, but building levees helps replace natural flood controls. Wetlands were very effective at filtering and cleaning water^[8], so to help with the ever increasing challenge of decreasing water pollution (often from agricultural runoff from the farms that replaced the wetlands in the first place), millions of dollars have been invested on water purification plants and expensive remediation measures. The USA came to understand how biologically productive wetlands are, so the USA passed laws limiting wetlands destruction, and created requirements that if a wetland had to be drained, developers at least had to offset the loss by creating artificial wetlands. One example is the project by the U.S. Army Corps of Engineers to control flooding and enhance development by taming the Everglades, a project which has now been reversed to restore much of the wetlands as a natural habitat for plant and animal life, as well as a method of flood control.

By 1993 half the world's wetlands had been drained.^[9] Since the 1970s, more focus has been put on preserving wetlands for their natural function — sometimes also at great expense.

The South African Department of Environmental Affairs and Tourism in conjunction with the departments of Water Affairs and Forestry, and of Agriculture, supports the conservation and rehabilitation of wetlands through the Working for Wetlands program.^[10] The aim of this program is to encourage the protection, rehabilitation and sustainable use of South African wetlands through co-operative governance and partnerships. The program is also a poverty relief effort, providing employment in wetland maintenance.

Over 90% of the wetlands in New Zealand have been drained since European settlement, predominantly to create farmland. Wetlands now have a degree of protection under the Resource Management Act.

Ramsar Convention

The Convention on Wetlands of International Importance, especially as Waterfowl Habitat, or Ramsar Convention, is an international treaty designed to address global concerns regarding wetland loss and degradation. The primary purposes of the treaty are to list wetlands of international importance and to promote their wise use, with the ultimate goal of preserving the world's wetlands. Methods include restricting access to the majority portion of wetland areas, as well as educating the public to combat the misconception that wetlands are wastelands.

Climate

Temperature

Temperatures vary greatly depending on the location of the wetland. Many of the world's wetlands are in temperate zones (midway between the North and South Poles and the equator). In these zones, summers are warm and winters are cold, but temperatures are not extreme. However, wetlands found in the tropic zone, which is around the equator, are always warm. Temperatures in wetlands on the Arabian Peninsula, for example, can reach 122°F (50°C). In northeastern Siberia, which has a polar climate, wetland temperatures can be as cold as -60°F (-5l °C).

Rainfall

The amount of rainfall a wetland receives depends upon its location. Wetlands in Wales, Scotland, and western Ireland receive about 59 inches (150 centimeters) per year. Those in Southeast Asia, where heavy rains occur, can receive up to 200 inches (500 centimeters). In the northern areas of North America, wetlands exist where as little as 6 inches (15 centimeters) of rain fall each year.

List of wetland types

See also

	Environment portal
	Ecology portal
	Earth sciences portal
	Sustainable development portal

References

Further reading

• Mitsch, W.J., J.G. Gosselink, C.J. Anderson, and L. Zhang. (2009) "Wetland Ecosystems". John Wiley & Sons, Inc., New York, 295 pp.
• Ghabo, A. A. (2007) Wetlands Characterization; Use by Local Communities and Role in Supporting Biodiversity in the Semiarid Ijara District, Kenya. Terra Nuova East Africa. Wetlands in drylands.
• 1987 U.S. Army Corps of Engineers Wetland delineation manual
• Dugan, Patrick (editor) (1993) Wetlands in Danger, World Conservation Atlas Series
• Brinson, M. (1993) A Hydrogeomorphic Classification of Wetlands
• Fredrikson, Leigh H. (1983) "Wetlands: A Vanishing Resource" Yearbook of Agriculture
• W.H. MacKenzie and J.R. Moran (2004) "Wetlands of British Columbia: A Guide to Identification. Ministry of Forests, Land Management Handbook 52. [1]

External links

• Wetlands: The Ecological Effect of Loss (Research article)
• (French)Pôle-relais zones humides littorales de la façade atlantique, Manche et Mer du Nord
• Marshlands of Iberá (in English and Spanish)
• Wetlands Water Quality Information Center, U.S. Department of Agriculture
• Centro Studi Naturalistici
• Wetland of Hong Kong