Swamps and marshes

Wetlands are areas of land where the water level is mostly above the ground. The main types of wetland are bogs, fens, swamps and marshes.

Bogs and fens occur in cold climates and contain plenty of partially rotted plant material called peat.

Marshes and swamps are found in warm and cold places. They have more plants than bogs and fens.

Marshes are in permanently wet places, such as shallow lakes and river deltas. Reeds and rushes grow in marshes.

Swamps develop where the water level varies - often along the edges of rivers in the tropic where they flooded, notably along the Amazon and Congo Rivers. Trees such as mangroves grow in swamps.

Half the wetlands in the USA were drained before most people appreciated their value. Almost half of Dismal Swamp in North Carolina has been drained.

The Pripet Marshes on the borders of Belorussia are the biggest in Europe, covering 270,000 sq km.