What is Peat?

Who is this guy called 'peat'? by M. Finlayson and M. Moser

Peat is a dark fibrous material created when 'decomposition fails to keep pace with the production of organic matter'. It is the first stage of transformation of plant matter into coal. Although peat is created under specific conditions (waterlogging, lack of oxygen or nutrients, high acidity or low temperatures), peat can be found in many types of wetlands. Marshes, swamps, floodplains and coastal wetlands may contain peat, however, where the peat deposits are greater than 300-400mm in depth, a distinctive variety of ecosystems are created. Known collectively as 'mires' these complex ecosystems (which include bogs and fens) are very susceptible to even the slightest change in hydrological regime, vegetation cover or grazing.

Bogs form where rain and snow directly feed an already high watertable. This results in waterlogged soil with reduced oxygen levels. Rainfall leaches nutrients from the soil, and acid is produced as the organic matter continues to slowly ferment. Bogs can thus be characterised by acid-loving vegetation. Of particular importance are the Sphagnum bog mosses which can hold more than ten times their dry weight of water.

Fens, on the other hand, are fed by ground water or by interior drainage into hollows (rather than by precipitation). These wetlands are higher in nutrient content than bogs, but are still able to produce peat. Their greater nutrient content and lower acidity means that fens support very different vegetation from bogs. Luxuriant and species-rich covers of reeds, sedges and herbs are not uncommon.

Drawn and condensed from: Finlayson, M and Moser, M. Wetlands. International Waterfowl and Wetlands Research Bureau (IWRB), 1991 and reprinted in Wetlands Australia, no. 6, July 1997, p. 7.