The Online Encyclopedia and Dictionary







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

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 saturates the soil. The result is a hydric soil , one characterized by an absence of free oxygen some or all of the time, and therefore called a "reducing environment." Plants (called hydrophytes or just wetland plants) specifically adapted to the reducing conditions presented by such soils can survive in wetlands, whereas species (called "upland" plants) intolerant of the absence of soil oxygen can not survive. Adaptations to low soil oxygen characterize many wetland species.


Wetland types

Wetland functions

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 , with shallow open water and reedbeds.
A temperate wetland in 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


  • Mitsch, William J., and James G. Gosselink, (1986). Wetlands, New York: Van Nostrand Reinhold, 1986, p. 539.
  • Campbell, Craig S., and Michael Ogden, (1999), "Constructed Wetlands In The Sustainable Landscape", New York: John Wiley & Sons, Inc., 1999, p.270.

External links

The contents of this article are licensed from under the GNU Free Documentation License. How to see transparent copy