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In physical geography, a wetland is an environment "at the interface between truly terrestrial ecosystems...and truly aquatic systems...making them different from each yet highly dependent on both" (Mitsch & Gosselink, 1986). In essence, wetlands are ecotones. Wetlands are found under a wide range of hydrological conditions, but at least some of the time water saturatess the soil. The result is a soil type (called hydric soil) that is unique to wetlands. The hydric soil supports plants (called hydrophytes) specifically adapted to these conditions and excludes species intolerant of them.

A subtropical wetland in Florida, USA, with an endangered American Crocodile

Table of contents
1 Types of Wetlands

Types of Wetlands

Functions of wetlands

By absorbing the force of strong winds and tides, wetlands protect terrestrial areas adjoining them from storms, floods, and tidal damage. Fresh water marshes are often on river floodplains.

A temperate wetland in Great Britain, with shallow open water and reedbeds

Wetlands are often filled in to be used for everything from agriculture to parking lots, in part because the economic value of wetlands has only been recognised recently: the shrimp and fish that breed in salt water marshes are generally harvested in deeper water, for example. Wetlands support a wide variety of wildlife (bird, plants, fish, mammals etc) and therefore the conservation of wetlands is of prime importance for the preservation of many species of wildlife. In 1962, the idea of wetlands conservation was born with a "List of Wetlands of International Importance". This was followed up in 1971 by the Ramsar Convention when conservationists from 23 countries met in the city of Ramsar, Iran on the shores of the Caspian Sea. There are now over 1,200 wetlands on the Ramsar List.

See also: United Nations Convention signatories, Wetlands International, The Broads National Park, Wildfowl and Wetlands Trust, Somerset Levels