Wetlands Portal


A wetland is a land area that is saturated with water, either permanently or seasonally, such that it takes on the characteristics of a distinct ecosystem. The primary factor that distinguishes wetlands from other land forms or water bodies is the characteristic vegetation of aquatic plants, adapted to the unique hydric soil. Wetlands play a number of roles in the environment, principally water purification, flood control, carbon sink and shoreline stability. Wetlands are also considered the most biologically diverse of all ecosystems, serving as home to a wide range of plant and animal life. Wetlands occur naturally on every continent except Antarctica, the largest including the Amazon River basin, the West Siberian Plain, and the Pantanal in South America. The water found in wetlands can be freshwater, brackish, or saltwater. The main wetland types include swamps, marshes, bogs, and fens; and sub-types include mangrove, carr, pocosin, and varzea.

The UN Millennium Ecosystem Assessment determined that environmental degradation is more prominent within wetland systems than any other ecosystem on Earth. International conservation efforts are being used in conjunction with the development of rapid assessment tools to inform people about wetland issues.

Constructed wetlands can be used to treat municipal and industrial wastewater as well as stormwater runoff and they also play a role in water-sensitive urban design.

Selected article

A river in the Amazon.
A river in the Amazon.
A várzea forest is a seasonal floodplain forest inundated by whitewater rivers that occurs in the Amazon River Basin. Along the Amazon River and many of its tributaries, high annual rainfall that occurs mostly within a rainy season results in extensive seasonal flooding of areas from stream and river discharge. The result is a 10–15 meter rise in water level, with nutrient rich waters.

Várzea forests can be split into two categories: low várzea and high várzea. Low várzea forests can be categorized by lower lying areas where the annual water column has an average height of more than 3 meters, where the period of flooding is greater than 50 days per year. High várzea forests are categorized as the areas where the average annual water column is less than 3 meters high and flooding periods are less than 50 days per year. Amazonian várzea forests are flooded by nutrient rich, high sediment white water rivers such as the Solimões-Amazon, the Purus, and Madeira rivers. This makes the várzea areas distinct from igapós, floodplains from nutrient poor black water. The water level fluctuations that the várzea experiences result in distinct aquatic and terrestrial phases within the year. Amazonian white water river floodplains cover an area of more than 300,000 km2, and várzea forests cover approximately 180,000 km2 of the Amazon basin. 68% of the Amazonian river basin is located in Brazil, with the remaining areas located in Bolivia, Colombia, Ecuador, French Guiana, Peru, Suriname, and Guyana. The várzea extends from this basin upward into the land before reaching slopes into the terra firme forests. (Full article...)

General images

The following are images from various wetland-related articles on Wikipedia.


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Alligator and python struggle in Everglades National Park.
Credit: Lori Oberhofer, National Park Service

Did you know...

that the Atchafalaya Basin is the largest wetland in the United States?
... that the Atchafalaya Basin is the largest wetland in the U.S.?

(Pictured left: The Atchafalaya Basin.)

Other "Did you know" facts...


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