Literature review
Wetlands and their significance in the ecosystem
Wetlands have been ignored in the past; they have been drained and filled to support agriculture, urban expansion and other developments. Recently they are receiving attention because of the value they contribute to the environment and society.
Wetlands are areas of marsh, peatlands, fen or water, whether natural or artificial, permanent or temporary, with water that is standing or flowing, fresh, brackish or saline, including areas of marine water, the depth of which at low tide does not exceed six meters (Ramsar, 1971). Wetlands are composed of physical, biological and chemical components such as water, soil, plants and animal species. Each wetland is ecologically unique because the functions and values they perform depend on their location in the landscape (Prasadi et.al, 2002).
As it has been noted by Barkett and Kusler (2000), the existence of wetlands in the transition zone between aquatic and terrestrial environments makes them to be exposed to changes in surface and ground water hydrology that are beyond limits of adaptation and tolerance of wetland species. Wetlands that depend primarily on precipitation as a primary source of water are most vulnerable to climate change. The vulnerability of these wetlands to climate change is caused by natural and man-made stresses that they impose on these wetlands.
Wetlands are among the world’s most productive and valuable ecosystems. Due to their unique