Peatlands, Past and Present

Peatlands are fascinating wetland ecosystems. They provide a habitat for a wide range of highly adapted plant and animal species. In addition to the floristic and ornithological richness, peatlands have been recognized for many other values. For instance, drained peatland soils often have good agricultural properties, and peat has been and still is in some places extensively used as fuel. In coastal wetlands peat has even been used for salt extraction. Furthermore, peat is an interesting material for science, as it contains information on the palaeoecological environment, climate change, carbon history, and archaeology. In north-western Europe, peatlands were once quite extensive, covering tens of thousands of square kilometres. However, most of them have been strongly exploited by humans during past centuries. Many peatlands have been cultivated for agriculture and forestry, or have been exploited by commercial or domestic peat extraction for fuel. As a result, only a very small part of north-western Europe’s peatlands remains today in a more or less natural state. This chapter focuses on the peat deposits and peatlands in north-western Europe that have formed since the Late Glacial (c.13 ka BP). First, the most common concepts in peatland terminology are explained, and the distribution of peatlands is described. Next, processes of peat formation and the relationship between peatforming processes and climate, hydrology, vegetation, and other factors are discussed. In the following section, frequently used classification methods are presented. A historical overview of the cultivation and exploitation of peatlands is given and the present land use and characteristics of peatland soils are discussed. The following section deals with methods of conservation and rehabilitation of the remaining mires. The importance of peatlands as palaeoecological archives is examplified. Finally, the role of peatlands as a source and/or sink of CO2 and the relations with climate change are briefly explained. Peat is the unconsolidated material that predominantly consists of slightly decomposed or undecomposed organic material in which the original cellular and tissue structures can often be identified. Peat forms in lakes and mires under waterlogged, anaerobic conditions.