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Peatlands: Formation, conservation status and biodiversity


What are peatlands?

Dürrerbühl bog (Allgäuer Moorallianz; photo: U. Riecken)
Dürrerbühl bog (Allgäuer Moorallianz; photo: U. Riecken)

Peatlands are ecosystems where the soil is always waterlogged thanks to precipitation, groundwater, or surface or spring water. Because of a lack of oxygen, dead organic material decomposes only very slowly if at all. Organic matter is thus created faster than it can be broken down. The result is the formation of peat (with upwards of 30 percent organic matter). Peat grows in thickness over time, creating the basis of a peatland habitat. Widely differing and in some cases highly specialised plant associations and animal communities emerge depending on the type of peatland.


Coastal fen (Kooser Wiesen, photo: A. Ssymank)
Coastal fen (Kooser Wiesen, photo: A. Ssymank)
Alder carr woodland (photo: U. Riecken)
Alder carr woodland (photo: U. Riecken)

Types of peatland

The formation and subsequent development of peatland depends on many factors. Various types of peatland can form depending on climate, geology, relief, hydrology and the nutrient balance.

Based on the origin of the water in the peat layer, peatlands can be basically classified into bogs, intermediate bogs and fens. In a bog, the excess water comes solely from precipitation (ombrogenous), in contrast to a fen, which is fed by groundwater and surface water (geogenous).

In an intermediate bog, the upper layers of peat have already risen so far that they are cut off from sources of water other than precipitation, while the lower layers of peat are still influenced by groundwater or surface water.


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Significance of peatlands for biodiversity conservation

Orchid (Platanthera spec.; photo: U. Riecken)
Orchid (Platanthera spec.; photo: U. Riecken)
Pearl-bordered fritillary (Boloria spec.; photo: U. Riecken)
Pearl-bordered fritillary (Boloria spec.; photo: U. Riecken)

The extreme conditions in terms of hydrology, nutrient balance and soil reaction mean that species have to be well adapted to life in a peatland habitat. The ecological communities characteristic of peatlands consist as a result of highly specialised plant and animal species. Due to their specialisation, many of these are poor competitors and not viable outside of a peatland environment. They also include a number of glacial relict species found today only in unusual locations such as peatlands. Species composition and diversity, however, depend on the type of peatland and differ widely, notably between the various climate zones. Tropical peatlands are thus among the most biodiverse ecosystems anywhere on the planet, whereas peatlands in Europe tend to feature comparatively few but rare species. With the destruction of peatlands, these characteristic species lose their habitats, and consequently most peatland species are endangered or critically endangered. Peatlands are thus valuable habitats for many rare species.


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Situation and conservation status of peatlands

Globally

Global distribution of peatlands (© Succow and Jeschke 1990)
Global distribution of peatlands (© Succow and Jeschke 1990)

Peatlands cover an area of some 4 million qkm worldwide and are found in 90 percent of all countries. They are very unevenly distributed around the world, with the largest areas in Canada, Alaska, Northern Europe, Siberia and Southeast Asia. Almost 80 percent of the world’s peatlands by area are still in their natural state. The majority of these intact peatlands are in sparsely populated areas of little use to agriculture, primarily in Canada, Alaska and Siberia. In parts of the world with high population pressure and land use, such as Europe and Southeast Asia, hardly any undisturbed peatlands remain. Large areas of peatland there have been drained for farming or forestry, the peat has been extracted or the land has been used for building or infrastructure. In Indonesia and Malaysia, peatland forest has been drained on a large scale in the last 20 years and converted into oil palm or acacia plantations. Some 900,000 qkm of peatland worldwide has been destroyed to such an extent that peat formation has ceased and the peat has been partly or entirely lost. The global stock of peat is declining by about 0.2 percent a year (Joosten 2012).

Europe

Loss of actively growing bogs in selected EU member states (after Succow & Joosten 2001)
Data table
Data table: Loss of actively growing bogs in selected EU member states (after Succow & Joosten 2001)

Europe’s greatest population density goes hand in hand with great demand for land and energy – with correspondingly high pressure of use on the countryside, including peatlands. Intact peatlands have become very rare as a result. Europe has suffered the biggest losses of any continent. Peat formation has ceased on 57 percent of former peatland and in many European countries peatland has been pushed back to less than 10 percent of its original extent.

In Germany, the United Kingdom, Iceland, Denmark, the Netherlands and Switzerland, the losses are mainly due to the large amounts of land needed for agriculture. In Finland, Ireland and Sweden, the main driver of peatland loss is large-scale peat cutting for energy generation. In other countries such as the Baltic states, Belarus and Russia, a key factor is peat extraction for use in horticultural and garden growing media (notably for Western Europe).

While in many states almost all peatlands are now degraded, there are still regions in Europe where peatlands are under lesser pressure of use. In Norway, for example, 80 percent of peatland by area still remains.

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Germany

Map of peatlands in Germany
Map of peatlands in Germany

Peat and peaty soils make up approximately 3.5 percent of German territory (12,600 qkm; Succow & Joosten 2001 and supplementary surveys of the Länder in 2014), primarily concentrated in the North German lowlands (78 percent) and the Alpine foothills. Peatlands are subject to greater than ever pressure of use due to increasing demand for food, resources, energy, and building land. Whereas peatlands remained largely untouched into the 17th century with peat formation continuing, about 90 percent of peatland today is in use (49 percent grassland, 23 percent arable land, and 15 percent timber plantation and forest; Tiemeyer et al. 2013). The use of this land is intensifying under the current agricultural policy regime with subsidies for biomass crops for biogas generation. Peat extraction, too, continues in Germany at a rate of 8.2 million cbm a year, 90 percent of it in Lower Saxony (as of 2012; Huy et al. 2013). All these uses of peatland entail drainage, which leads to peat loss, soil subsidence and destruction of the peatland. The near-natural peatlands that remain are harmed by widespread pollution with nutrients from adjacent farmland and the air.

Lack of rainfall and rising annual average temperatures due to climate change also have adverse effects on the hydrology and hence the sink function of near-natural peatlands.


Areas of peatland in the German Länder (after Grosse-Braukmann 1997)
Data table
Areas of peatland in the German Länder (after Grosse-Braukmann 1997)

Peatlands inside protected areas are also degraded to a large degree. Intact, peat-accumulating bogs have been pushed back in Germany to one percent (140 qkm) of their former extent (Joosten 2012). According to the German Red List of Threatened Habitats, all peatland habitat types are endangered or critically endangered. Most peatland habitat types are therefore under special protection.


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