Wetlands, whether swamp, bog, marsh or fen, are waterlogged areas where aquatic plants thrive. Some, like the Okavango Delta, dry up seasonally. Others, like the fenlands of England, are permanently wet. The shallow water can be fresh, brackish or salty, as wetlands often occur where a terrestrial habitat meets a marine one. They can be an effective natural flood control mechanism, allowing excess river water, for example, to disperse over large areas, and are particularly important for birds.

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