Long-term effect of forest drainage on the peat carbon storage of pine mires in Finland. Background Information Organic soils accumulate in marshes, bogs, and swamps where anaerobic conditions reduce the rate of organic matter decomposition well below the rate of production. Bogs have no inflow or outflow areas and support acidophilic mosses. Fens receive some drainage inputs from surrounding mineral soils and supports marsh-like vegetation. Peat is a term commonly used to refer to fibric material.
Hemic material is intermediate with respect to decomposition.
Organic soils form under saturated conditions. Aerobic conditions, if they occur at all, are likely at the soil surface above the water table. As depth increases, conditions become anaerobic due to the continual presence of water. In some instances, organic plant material continues to build up above the level of the water. This situation produces a bog in which the major portion of the growing surface receives no input from underlying or adjacent mineral soils.