Wetlands cover a large part of the earth surfaceThe total area of wetlands in the world is difficult to estimate because not all wetlands have been identified and inventoried. Estimates of the total wetland area range from 500 to 4,000 million hectares. The most likely estimate is 700-800 million hectare. It is hard to estimate the number of people living in or near wetlands. It is estimated that 70% of the world's population live near ocean coastlines.
Wetlands perform a number of very important ecological and hydrological functionsWetlands form the transition zone between dry land and water. In inland areas, examples are the floodplains between the uplands and the river, or the swamps between upland and lakes. In coastal areas, mangroves and estuaries are the link between the sea and the land.
Because of their position between dry and wet ecosystems, wetlands act as buffer zones for water, sediment, polluting substances and nutrients. They absorb nutrient and sediment run-off from the upland (e.g., from urban centres or agriculture) and prevent the eutrophication of lakes and seas.
Wetlands are very productive, and support large numbers of plant and animal species, including many birds, reptiles, fish, and mammals. Wetlands are thus very important for biodiversity.
Wetlands also act as hydrological buffers, protecting upland areas from floods. Wetlands help regulating local climates through vegetation growth and evapotranspiration.
Wetlands support the livelihoods of large numbers of people living in or close to wetlandsWetlands provide many services and products to human populations: drinking water, food, building materials, medicine, etc. Many economic activities are carried out in wetlands: fishing, agriculture, forestry, fuel production (e.g., peat and wood), transport, brick making, tourism. Many wetlands serve as treatment plants for domestic or industrial wastewater.
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Wetlands Introduction
