Types of wetlands
All shapes and sizes
There are also human-made wetlands such as fish and shrimp ponds, farm ponds, irrigated agricultural land, salt pans, reservoirs, gravel pits, sewage farms and canals.
There are many different ways of categorising wetlands, and numerous different types. Most large wetland areas are a unique mosaic of different wetland types. For example, within the The Kafue Flats are found grasslands, lagoons, marshes, swamps and reed beds.
Coastal WetlandsCoastal wetlands are found in the areas between land and open sea that are not influenced by rivers such as. shorelines, beaches, mangroves and coral reefs.
A good example are the mangrove swamps found in sheltered tropical coastal areas. The partly submerged roots of mangrove trees spread out beneath the water to trap sediment and prevent it being washed out to sea. Around 70% of tropical coastlines are mangrove-lined.
Some mangroves are strategically planted between land and sea to stabilise shores and to protect communities from violent storms and powerful waves. The result is an area of stillness and tranquillity where fish breed, wildlife takes refuge, and local people earn a living from occupations as diverse as charcoal burning and bee keeping.
Shallow lakes and pondsThese wetlands are areas of permanent or semi-permanent water with little flow. They include vernal ponds, spring pools, salt lakes and volcanic crater lakes. They are small, shallow, intermittently flooded depressions in grasslands or forests, and are often only wet in winter and early spring.
BogsBogs are waterlogged peatlands in old lake basins or depressions in the landscape. Almost all water in bogs comes from rainfall. Bogs have specialised and unique flora that have evolved in their nutrient-poor and acidic conditions, including for example the carnivorous pitcher plant. As bogs are unsuitable for agriculture, forestry or development they offer an undisturbed habitat for a wide range of species, including moose, black bear, lynx, snowshoe hare and mink.
In addition, bogs are used by many species of migratory birds, providing a safe habitat in which to breed, rest and feed. A particular kind of bog is found on the coastal plain of the southeasteern United States. Pocosins are evergreen shrub bogs typically found on high areas of a flat water-logged landscape.
Marshes and SwampsAlso known as palustrine wetlands, marshes, swamps and fens account for almost half of all wetlands throughout the world.
Marshes are one of the broadest categories of wetlands and in general harbour the greatest biological diversity. Marshes form in depressions in the landscape, as fringes around lakes, and along slow-flowing streams and rivers. Marshes are dominated by floating-leafed plants like water lillies and duckweed.
Marshes slow down the rate of rainfall drainage and control its flow into rivers, lakes, and streams.
EstuariesThe area where rivers meet the sea and water changes from fresh to salt can offer an extremely rich mix of biodiversity.
These wetlands include deltas, tidal mudflats and salt marshes. Mudflats and seagrass beds in particular provide a rich diet for many species of insects, birds, fish, turtles and other species.
It engages in a wide variety of projects to protect habitats and conserve these vital ecosystems.