PEATLAND

A type of Ecosystem, also referred to as a Mire, in which organic matter is produced faster than it is decomposed, resulting in the accumulation of partially decomposed vegetative material called Peat. In some mires peat never accumulates to the point where plants lose contact with water moving through mineral soil. Such mires, dominated by grasslike sedges, are called Fens. In other mires peat becomes so thick that the surface vegetation is insulated from mineral soil. These plants depend on precipitation for both water and nutrients. Such mires, dominated by acid-forming sphagnum moss, are called Bogs. Peatlands are most extensive in northern regions. They develop where drainage of water is blocked, precipitation is retained, and decomposition of organic matter is slowed. Some peatlands form when accumulated organic matter and sediments fill in a pond or basin above the level of the water table. Called Raised Bogs, these sphagnum-dominated basins become so high in acidity and low in groundwater minerals that sedges and grasses retreat to the edges. Less commonly, sphagnum moss may form a floating mat over the water, then thicken and support associated vegetation, mostly Heaths, and eventually reach the bottom. Such mires are called Quaking Bogs. Under certain conditions, especially deforestation, sedge and sphagnum invade higher ground. The peat they form becomes compressed and blocks the drainage of water. These are called Blanket Mires or Moors. Also see Marshland.