Peat

Peat is an accumulation of partially decayed vegetation or organic matter that forms in waterlogged, acidic conditions in wetlands. It develops when plant material builds up faster than it can decompose because oxygen is limited and microbial activity is slowed by saturation. Peatlands, including bogs and fens, are the primary environments where peat accumulates.

Formation and composition: Peat layers grow as plant debris accumulates and decomposes only partially. Sphagnum mosses often contribute to the acidity and water-holding capacity of these systems. Peat is commonly classified by the degree of decomposition into fibric (least decomposed), hemic, and sapric (most decomposed). In peat geology, the upper fresh material is called the acrotelm and the deeper, more stable portion the catotelm.

Uses and extraction: Peat has historically served as a fuel source in some regions and as a horticultural growing medium. Harvesting peat impacts carbon storage and hydrology, leading to regulatory controls in many countries and a shift toward conservation and restoration of peatlands to preserve biodiversity and carbon stocks.

Ecological and climate role: Peatlands are important long-term carbon sinks and support unique plant and animal communities adapted to waterlogged, acidic conditions. Drainage or burning of peatlands releases carbon dioxide and methane, contributing to climate change. Restoration efforts aim to re-wet peatlands, restore natural hydrology, and reestablish vegetation such as Sphagnum to slow decay and recover habitat.

Geography and significance: Peatlands are found worldwide but are most extensive in boreal and temperate regions of Europe, North America, and parts of Asia. In soil science, peat is recognized as an organic soil type, often categorized as histosol.