Different types of wetlands


The wonder of wetlands



great land Wetlands are highly productive ecosystems that provide the world with nearly two-thirds of its fish harvest. They take many forms: marshes, estuaries, mudflats, mires, ponds, swamps, deltas, coral reefs, billabongs, lagoons, shallow seas, bogs, lakes, and floodplains are all examples. Almost every country in the world possesses a wetland of some description.


Mangrove swamps are, typically, tropical wetlands. The partly submerged roots of mangrove trees spread out beneath the water to trap sediment and prevent it being washed out to sea. Some mangroves are strategically planted between land and sea to stabiliz e 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.


Floodplains are areas of land seasonally flooded by rivers and lakes, and are found in many parts of the world. One of the most significant is Kafue in Zambia. This vast area of grassland, hot springs, swamp, and woodland straddles the River Kafue which floods every December to reach a peak in May; then the waters subside until they hit their lowest ebb in November. Kafue is also an extraordinary habitat for birds: it is host to more than 400 species.


In contrast to constantly changing floodplains, bogs are still and moist. Largely fed by gentle rainfall, they contain organic matter that slowly builds up over many years to form rich deposits of peat. Fens also produce peat, but unlike bogs they are nou rished by streams and rivers. Marshes slow down the rate of rainfall drainage and control its flow into rivers, lakes, and streams.


Stretching along the coasts of the Netherlands, Germany, and Denmark is the marshy, salty, and sandy Waddensee - part of the North Sea. The water is shallow, so the seabed is exposed when the tide ebbs. Hundreds of seals and millions of migratory birds are attracted to the Waddensee's mudflats, sand bars, salt marshes, and barrier islands, which together are among the most important feeding grounds in northern Europe. This wetland also supports 80 per cent of the North Sea's plaice stocks, half the sole, and nearly all the herring.


These brief descriptions serve to illustrate the variety of wetlands. But despite such diversity, they have one thing in common. They are all threatened.



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