Peats

Peat is an accumulation of partially decayed organic matter, mainly plant material, that forms in waterlogged, low-oxygen conditions. It develops when plant debris accumulates faster than it decomposes, creating thick, water-saturated layers in peatlands.

The formation of peat is driven by persistent wetness, low temperatures, and acidic conditions. Sphagnum mosses are especially important in many peatlands; they hold water, release organic acids, and create an environment that slows microbial breakdown. Over time, successive layers of plant material build up, with the upper layers remaining relatively fresh (acrotelm) while deeper, more decomposed material (catotelm) becomes more humified.

Peat is often classified by degree of decomposition into fibric (least decomposed, recognizable fibers), hemic (moderate decomposition), and sapric (highly decomposed, few recognizable plant parts). Peatlands host distinctive landforms, including bogs that are rain-fed and acidic (ombrotrophic) and fens that receive groundwater and nutrients (minerotrophic).

Ecologically, peatlands are important for water regulation, biodiversity, and especially carbon storage. They contain large stores of organic carbon and act as buffers against floods. Draining or draining and draining-related disturbances raise the rate of peat oxidation, releasing carbon dioxide and other greenhouse gases. Peat has historically been mined for fuel and horticultural use, though many peatlands are now protected or restored to slow carbon loss. Global distribution is concentrated in boreal and temperate regions, with extensive peatlands in parts of Canada, Russia, Finland, and Ireland.