Wetlands are land areas that are 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 (permanently or seasonally saturated by water, resulting in anaerobic conditions). 


A mangrove tree surrounded by its pneumatophores, in Moreton Bay, Queensland. image: wikipedia/ BoundaryRider

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 plants and animals


Peat bog in Frontenac National Park (Québec, Canada). image: wikipedia/Boréal

Wetlands occur naturally on every continent except Antarctica,  the largest includes the Amazon River basin, the West Siberian Plain, and the Pantanal in South America.

Water types

The water found in wetlands can be freshwater, brackish, or saltwater.

 The main wetland types include:

  • swamps - are wetlands that are forested 
  • marshes - wetlands that are dominated by herbaceous rather than woody plant species.
  • bogs or mires - accumulates peat, a deposit of dead plant material—often mosses, and in a majority of cases, sphagnum moss.  chemistry is is acidic and low in nutrients.
  • fens - have specific water chemistry such as pH neutral or alkaline, with relatively high dissolved mineral levels but few other plant nutrients.


A black alder swamp in Germany. image: wikipedia/Bernd Schade

 and sub-types include:

  • mangrove - A mangrove is a shrub or small tree that grows in coastal saline or brackish water
  • carr - transition between reedy swamp and the eventual formation of forest in a sub-maritime climate.
  • pocosin - wetland that lacks flowing water, with deep, acidic, sandy, peat soils a type of bog
  • varzea - aka are swamp forests which are inundated with freshwater, either permanently or seasonally.


Wetlands can include swamp regions and marsh regions. image: wikipedia/Douglas A. Wilcox et al

Environmental concerns

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.

How wetlands can help urban areas

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

Source, adapted from: Wetland. (2018, February 2). In Wikipedia, The Free Encyclopedia. Retrieved 03:51, February 3, 2018, from https://en.wikipedia.org/w/index.php?title=Wetland&oldid=823676074