Rain bog

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Nature reserve " Ewiges Meer ", high moor area of ​​a residual moor in East Friesland

Rain Moore , also ombrotrophe Moore or raised bogs called (in Upper Bavaria and felts ) are mineral low-salt, sour and wet habitats with an extreme of these conditions adapted flora and fauna . Rain Moore, unlike fens supplied exclusively from precipitation (Ombrotrophie) and registered from the air mineral salts and make a special hydrological , ecological and evolutionary bog type is until millennia währendem during its centuries growth peat mosses play a crucial role as Torfbildner.

Rain bogs are seriously endangered by peat extraction and mineral salt input from the environment ( agriculture , industry ). There are hardly any living and growing rain bogs today. The last large rain moor areas are in Western Siberia and Canada .


The terms rain bog and raised bog are used synonymously. Due to the peat formation, rain and raised bogs grow upwards. To a certain extent, they resemble peat moss sponges soaked with water, which are more or less elevated in the landscape. Hence the term raised bog, which strictly speaking only refers to the classic clock-glass-shaped bogs of north-west Germany. The moors are not influenced by groundwater or surface water rich in mineral salts, but are only nourished by precipitation - mainly rainwater (hence the name). The term rain bog thus unites all bogs with little or no bulging, which are characterized by an extreme lack of mineral salts and other resulting ecological properties.

Origin and structure

Stratification of a raised bog: plant remains, white peat and black peat (from top to bottom)
Growth of a "classic" raised bog in northwest Germany

A living raised bog needs a damp, balanced climate to grow . The amount of precipitation must exceed the loss of water through runoff and evaporation. In addition, the precipitation must be evenly distributed over the year.

The rain bogs in Europe have been developing for around 11,000 years (beginning of the Holocene ) after the last ice sheets retreated . With regard to its origin, a distinction silting raised bogs and ungrafted raised bogs . The former emerged secondary from the silting up of lakes or from silting oxbow lakes of rivers (see figure on the right in the sequence). Initially, fens developed under the influence of groundwater (mineral soil water ). A lack of oxygen and a high degree of acidity in the constantly moist substrate inhibit the decomposition of dead plant parts and lead to the formation of peat . The raised bog grows very slowly above the level of the groundwater level, hence the name raised bog. After the resulting peat slowly grew out of the influence of the mineral soil water, the growth turned into a raised bog, which means that from now on these bogs were only fed by rainwater that was low in mineral salts. True-to-root raised bogs , also known as swamp bogs , were created directly on the mineral subsoil of areas poor in mineral salts without previous bog formation (see figure on the left in the sequence) either as primary bog formation through swamping of previously dry mineral soils, for example as a result of clearing, climate change, reduced seepage, or secondary by growing a raised bog onto the neighboring mineral soil. The formation of a typical raised bog is a very slow process that takes centuries to millennia, even if it is favorable and undisturbed. There are also a number of so-called transitional and intermediate moors, which combine characteristics of raised and fens in different proportions (see definition of moors ).

The main peat formers are the rootless peat mosses, which only grow slowly upwards, while at the same time the lower part pits in the absence of air. Depending on the geographical location, different types of peat moss are involved in the construction of rain bogs. The growth rate of peat substance is only about one millimeter per year.

Building a growing bog

Growing bogs can be divided into two layers. The "Akrotelm" ( Greek. : Akros = maximum; telma = sump) is the upper region and includes the vegetation layer and the peat ground . The fresh organic substances (peat formation horizon) are created there through the growth and death of plant parts. The “Katotelm” (Greek: kato = below) is the water-saturated area below with less biological activity. Due to the small number of soil-forming processes still taking place, this layer is counted as part of the geological subsurface and referred to as the peat conservation horizon. In rain bogs, the top layer of peat is called white peat, as it consists of largely undecomposed light brown peat moss. The lower peat layer is black peat, which is already well humidified and has a black-brown color with still recognizable plant remains.

Forms of rain bogs and distribution

Spread of bogs and rain bogs dominated by peat mosses on earth

The formation of rain bogs depends on the climate, i.e. the amount of precipitation and the amount of evaporation, which in turn are decisively determined by the temperature. Furthermore, the relief of the terrain influences the runoff and thus the shape of a rain bog. This results in a geographical limitation of the formation of rain bogs. Conditions that favor raised bog growth are mainly found in North America (Canada, Alaska ), Northern Europe and Western Siberia, South America , Southeast Asia and the Amazon basin . Here, bogs of all kinds and peat deposits totaling four million square kilometers were created, which means that they cover three percent of the earth's land area. In the southern hemisphere, bogs with low mineral salts are rarely made up of peat moss. Peat moss rain bogs only exist on the Tierra del Fuego islands . The most peat-rich countries in the tropics are found in Southeast Asia. In many cases it is not yet clear how the growth of these bogs takes place because there is no moss here.

Ceiling moors

Ceiling bog in Connemara , Ireland

In heavily oceanic regions, so-called blanket bogs are formed when there is high, very regularly distributed rainfall (on more than 235 days a year). These mostly very thin peat coverings with no clear surface structures cover hills and valleys in the landscapes of Ireland , Scotland , England and Norway in Europe . In North America , blanket bogs are mainly found east of Hudson Bay in Canada . These bogs are often still under the influence of mineral soil water (groundwater). Overhead bogs do not occur north of the 65th parallel.

Plan rain bogs

Due to their proximity to the sea, plan rain bogs are also known as coastal rain bogs or Atlantic rain bogs. In the distribution area of ​​the ceiling moors, there are also slightly curved plan rain moors with a weak surface relief in a level position. The area of ​​the plan high moors in Europe stretches from Ireland to the east via southern Norway to southwest Sweden and north to the Lofoten Islands . In North America, plan raised bogs can be found in the Great Lakes area (especially in Minnesota and Ontario ). Plan high moors are also fed exclusively by rain.

Plateau rain bogs

Profile section through a plateau rain moor in north-western Europe

In the less oceanic climatic areas of north-western Europe (lower rainfall) the rain bogs take on the classic clock-glass-shaped arched shape and are called plateau rain bogs ("raised bog"). They grow more in the middle than in the peripheral areas. This leads to a bulge in the central part, from which the raised bogs owe their name. This bulge can be several meters. As a result, the edge areas are more or less steeply inclined. They are called edge hangers . The edge slopes of larger moors are traversed by drainage channels (so-called rills), through which the excess water is drained.

Further characteristic structures of these raised bogs are the flat, tree-free raised bog core (rain bog or raised bog width) with a characteristic micro-relief of flat, wet depressions (Schlenken), which alternate with drier peat moss dome (Bulten) ( Bult-Schlenken complex , see illustration). Larger accumulations of water in the middle of the raised bogs are referred to as scour or bog eyes ( humic acid-rich waters), the wet areas on the outer edges as edge lagg.

Real ombrotrophic raised bogs in the north-west German lowlands show a mostly distinctive two-part structure in black peat (strongly decomposed) and white peat above (less decomposed). This change is a result of changes in the water balance of the respective bog. White peat has grown faster than black peat in wetter conditions. This change is due to a climate change with high precipitation and low evaporation around 1000 to 500 BC. Chr. Returned. This resulted in locally different peat moss growth and the associated formation of the black peat-white peat boundary layer, which did not develop in all raised bogs at the same time.

Mountain moors

Profile section through a mountain moor in the Ore Mountains

In mountains with high levels of precipitation, rain bogs also occur in the montane area - and more rarely also in alpine areas (i.e. above the tree line), which, due to the slope, often have a characteristic asymmetrical or non-concentric shape. Mountain rain bogs can be divided topographically into:

  • Plateau rain bogs in flat zones
  • Sloping rain bogs - these are bogs on a slope that are not real flow bogs ; the upper parts of the bog are fed more by inflow water and are mostly flat. The lower parts of the bog, which are exclusively fed by rainwater, can, however, reach considerable thicknesses. The lower edge slope is often very steep and the typical waterlogging zone of the lagg is usually missing (see above). Scour, shallow blanks and rills are just as present as in the classic raised bogs.
  • Saddle rain bogs - mostly elongated bogs in a pass location , which also have some water entry from the flank slopes, rare; the edge areas resemble the slope moor, the central areas the plateau moor
  • Summit and ridge bogs - very rare

However, all these bog forms can also represent the edge zones of fens or merge into them.


Kermimoore are also known as shield moors or strand or blank moors. They have a weakly domed shape. The moor surface rises continuously from the wide lagg zone to the center. The kermis are string-shaped peat moss bulbs that are arranged along the contour lines. The Schlenken (Flarke) are mostly formed trough-like and can hardly be distinguished from the scour from the outside. Ever larger pools are formed in the central area of ​​these moors. In northern Russia and in western Siberia, Kermimoore often appear in huge complexes that have grown together. In Finland , upland shield moors can also be found in the central and northern boreal coniferous forest zone .


Profile section through an aapamoor in North Karelia

Aapamoore (English "aapa fen", "string bog") are also referred to as string bogs. At the northern limit of the rain bogs in the subpolar zone (north of the 66th parallel of the northern hemisphere), raised bogs can only develop like islands within bogs supplied by mineral soil water. These islands are irregularly distributed on a level surface; on slopes they are arranged to form walls parallel to the slope. The walls enclose strips of bog that have been soaked through mineral soil. These are called "Rimpis" using a Finnish word. The main distribution area of ​​the Aapamoore are the Scandinavian mountains, central Finland and Karelia as well as northern Siberia. In North America, it is mainly Alaska that has aapamoore due to the cold continental climate. Frost effects play an important role in the bogs shown. Ground ice can be found in the strands of the moor until summer.


Palsamoore (English "palsa bog") are also known as Palsenmoore . In the border area of ​​the Arctic permafrost ( tundra ), the strands of the aapamoore can grow into meter-high peat hills. The so-called palsas , like the aapamoore, are often located in the middle of the bogs supplied by mineral ground water. Some of them are surrounded by water-filled trench-shaped depressions. Peat growth is hardly pronounced, these bogs are peat beds from warm times and were only arched up by ice cores growing inside as the climate became colder. These ice cores enlarge from year to year due to the thawing and freezing processes of the surrounding water. The low temperatures prevent complete decomposition of the organic material.

Polygon bogs

Polygon moor made of shallow ponds with a characteristic polygon structure

Polygon bogs are widespread in the arctic and subarctic plains of Siberia and North America, where they cover large areas. They are bound to frost pattern and ice wedge floors . A sparse peat-forming vegetation can remain in the inner honeycomb-like surfaces of these frost pattern soils ( cryoturbation ) and is supplied with sufficient moisture during the short summer, since the meltwater is prevented from draining by the raised polygon edges. The peat cover reaches a thickness of 0.3 to 1 meter.

Rain swamps in the northern hemisphere

  • Asia : The West Siberian rain moor area alone covers 700,000 km². The large moors reach arches of up to 10 m in the center. They mainly belong to the Kermimoore rain bog type. They are also known as strand and blank bogs. They represent the most important form of rain bogs on earth. The Wassjugan bog in this region alone , the largest bog system on earth, covers more than 50,000 km². The peat stores are estimated at over 14 billion tons.
  • North America : From Alaska in the west to the coasts of the Atlantic Ocean in the east, a moorland spreads out that is comparable in extent to that of Western Siberia. The zone of palsa and aapamoore (“string fens”) is followed by a zone of arched rain bogs. In the direction of the oceanity gradient from east to west, blanket bogs are widespread east of Hudson Bay. These are replaced to the west by plateau rain bogs in the Great Lakes region and finally by Kermi bogs.
Hochmoorkolk Wildsee near Bad Wildbad, Black Forest
  • Europe : The largest Central European rain bogs are the southern North Sea coastal area and the Alpine foothills. As in North America, there is a sequence of rain bog types along the oceanic gradient here from northwest to southeast. Through the use of peat, the rain bogs are broken down and cultivated with the exception of a few remains (less than 10% of the original area). The largest contiguous raised bog in Central Europe was the Bourtanger Moor , which originally covered an area of ​​around 2,300 km² with the Dutch part. Other large raised bogs are the Teufelsmoor northeast of Bremen, as well as the Vehnemoor (peated) and the Esterweger Dose (formerly about 80 km², peated) between Oldenburg and Papenburg. The high moors in the Harz , Solling , Thuringian Forest ( Großer Beerberg , Schneekopf - Teufelsbad, Fichtenkopf, Saukopf), Giant Mountains , Ore Mountains , Fichtelgebirge and Rhön ( Black Moor , Red Moor ) are comparatively small. In the Black Forest , a large area of the Wildseemoor has been placed under protection, in the Vosges a larger area is protected on the Tanet (French: le Tanet), north of the Col de la Schlucht . Furthermore, there is an area rich in moorland in the Alpine foothills formed by Ice Age glaciers . The Wurzacher Ried (Haidgauer Regenmoorschild) is considered to be the largest and best preserved rainmoor in Central Europe. Other rain bogs and rain bog landscapes are, for example, the Federsee , the High Fens in the German-Belgian border region, the Eternal Sea near Aurich and the Lengener Sea near Wiesmoor. The last Baltic raised bogs are currently being peeled off. In 2003, Estonia exported 3.6 million m³ of peat for the western European horticultural sector, that is more than 60 percent of the country's production. In Lithuania , 60 percent of the excavable peatland has been prepared for mining or is already being pitted.


Pale moss cushion with sundew, cranberry and rosemary heather

Rain bogs occupy a special position in the material cycle of nature. Their self-regulating power distinguishes them from all other ecosystems on earth.

Moors are habitats with a positive material balance. The formation of organic matter is greater than its decomposition and thus its consumption. This increase in organic matter and the deposition in the form of peat is only possible at locations with excess water. If the water supply is sufficient, the moor grows continuously. The peat layers are the result of the assimilation activity of the plants that used to grow on the surface. Thus they accommodate solar energy stored for thousands of years. This makes peatlands huge sinks for carbon and nitrogen . The most important group of plants in rain bogs are the peat or white moss ( sphagnum ), which build up the bog. Peat moss ensures that the raised bogs grow in height. During the annual vegetation period , the small plants grow between one and 30 centimeters in height. The annual growth in height of half a millimeter to one millimeter results from peating the dying plant remains downwards.

Water balance

Habit of a peat moss plant

An important property of rain bogs is their storage and absorption capacity for water. As bogs grow up, they accumulate water. The volume fraction of water in the peat body can be up to 97 percent. With a stronger water supply, bogs can expand their volume and damming the water on the surface. As a result, the peat body swells and shrinks (moor breathing, oscillation). Due to the anatomical peculiarities of the peat moss, rain bogs have a kind of self-regulating water regime. The tightly upright growth habit of the individual, tightly packed, rootless moss plants require capillary conductivity and are thus able to raise the water level. In addition, the leaves of the peat moss can store more than 30 times their dry mass in water in their large storage cells (hyaline cells) . The padding also increases the total pore volume. Due to the high storage capacity for water, discharge peaks into the environment are avoided in heavy rain. In periods with little precipitation, the capillary action always ensures a supply of water from the lower layers of the bog. When superficial drying occurs, the storage cells of the peat moss fill with air and become pale as a result. Solar radiation is reflected and this limits evaporation.

Material balance

Raised bogs are extremely low in mineral salts ( oligotrophic ) habitats. They are particularly characterized by a lack of nitrogen , an important nutrient element for plants. The permanent water saturation (lack of oxygen) causes incomplete decomposition of plant residues. Complete degradation ( mineralization ) can only take place in the upper layers of the moor (Akrotelm, see above), where there is still sufficient oxygen for microbial activity. Peat mosses have the ability to bind minerals and release hydrogen ions (H + , protons ) in return. In exchange, the peat moss absorbs minerals. In this way, the plant improves its growth conditions and creates an acidic environment for itself that it can endure, but in which competing plants have no chance of survival. Rain bogs have a pH value of 3 to 4.8.


The climate of a raised bog is more continental than that of its surroundings and is characterized by large, sometimes extreme temperature differences between day and night, but smaller differences in the annual cycle.

The more humid the soil, the more heat has to be added to reach a certain temperature. The heat capacity of a water-saturated peat soil is therefore high. The thermal conductivity of the peat, on the other hand, is low. The moor therefore only heats up very slowly over the course of the year and only cools down slowly in late autumn. In severe winters, the raised bog can freeze several meters deep. In this case, the bog remains frozen deep into the early summer as the sun's energy is hardly transmitted downwards. In June, the temperature is between zero and ten ° C at a depth of 10 to 20 centimeters. The consequence is a later start of the growing season . In contrast, the raised bog freezes much more slowly at the beginning of winter than the surrounding waters and sometimes remains free of snow and ice in warmer winters. Since a raised bog has a significantly different temperature than the air masses above it during these seasons, ground fog is common here.

When exposed to sunlight in summer, the dark peat on the surface heats up quickly. Due to the low thermal conductivity of the peat, which hardly dissipates heat to the layers below, extreme temperature differences between night frosts on a clear night sky and up to 70 ° C heat on sunny days can occur on the surface. Temperature fluctuations between 4 and 40 ° C within 12 hours near the surface are also not uncommon in Central European raised bogs. Individual measurements showed up to 77 ° C in a mountain bog. Since the surface of the moor is usually not covered with tall vegetation, the heat energy can radiate unhindered without the insulating properties of the peat, as is the case with mineral soils, from the depths. When the night sky is not cloudy and the humidity is low, night frosts can occur in the moor even in summer.

Intact raised bogs not only store enormous amounts of rainwater, they also have a decisive influence on the regional climate. Dry, warm air is cooled and humidified by the evaporative cooling, while warm, water-saturated air is forced to rain down. Large, extensive moors encourage their own growth. According to the average temperature, raised bog regions are the coldest in all seasons. Even today, cities in these moor regions have a "night-cold climate" despite being close to the coast.

Living world

The extreme lack of mineral salts, the low pH value and the permanent water saturation of the raised bog habitats result in a highly specialized, unique flora and fauna with a large number of endangered species.

Flora and vegetation

Colorful peat moss group with bell heather ( Erica tetralix )
Reddish peat moss ( Sphagnum rubellum )
Vaginal cottongrass ( Eriophorum vaginatum )

Plants that can cope with the extreme conditions in the raised bog are specialists and hunger artists. In many cases, special adaptations and strategies have been developed. So raised bog specialists thrive exclusively in raised bogs. The rain moor centers are usually tree-free.

Adaptations of the plants

An adjustment to the simple life in the bog have carnivorous plants ( carnivory found): Some species catch insects, they digest and can absorb additional nitrogen and mineral salts. The round-leaved sundew ( Drosera rotundifolia ) has reddish glands on its round leaves. These secrete a sticky liquid that, for example, attracts ants. They get stuck on the sticky glands and trigger a movement stimulus in the sundew. The sticky, finger-like protuberances with glands lean over the prey and roll up the insect with the leaf edges. A digestive juice, which is similar to the gastric juice of animals, releases the plant-usable substances from the insect. The sundew thus covers the need for nitrogen that is not available in the soil. The Venus flytrap ( Dionaea muscipula ) is native to the moors in North and South Carolina in the eastern United States. There the palm-sized plant sets up its folding traps in summer to catch insects and spiders.

Dwarf shrubs, which are almost all members of the heather family (Ericaceae), are characteristic of the flora of the rain bogs. These include, for example, the bog rosemary ( Andromeda polifolia ), the heather ( Calluna vulgaris ), the cross-leaved heath ( Erica tetralix ), the cranberry ( Vaccinium oxycoccos ). These dwarf shrubs form a so-called mushroom root ( mycorrhiza ) with fungi . This community allows them a better absorption of the scant soil minerals. It is also noticeable that the leaves of these plants are usually thick-fleshed and equipped with a thick epidermis . In addition, the leaves are covered with a layer of wax (cuticle) and the stomata are usually sunk. These characteristics represent an adaptation to the nutrient deficiency and the extreme temperature fluctuations. Sundew and cranberries can develop their roots in the multi-storey building and thus prevent the oxygen deficiency caused by the peat moss, which is growing higher and higher.

Peat Moss and Peat Moss Societies

In addition to peat moss, characteristic peat-forming plants in rain bogs are cotton grasses ( Eriophorum ), sedges ( Carex ) and turf rushes ( Trichophorum ). The vaginal cottongrass ( Eriophorum vaginatum ) has a clump-like habit. If the water supply is good, it will always be overgrown by the peat moss. With its fraying leaf sheaths, it contributes significantly to the formation of fibrous peat.

The individual peat moss species of the raised bogs have different moisture requirements. Yellowish green species such as the spit peat moss (Sphagnum cuspidatum) , the Baltic peat moss ( Sphagnum balticum ) or Sphagnum dusenii grow in very wet places and in ditches . Accordingly, the plant community in the water-saturated areas is called the Green Peat Moss Schlenken Society ( Cuspidato-Scheuchzerietum palustris ). This society is complemented by the mud sedge ( Carex limosa ), white schnabelried ( Rhynchospora alba ) and the rare bladder rush ( Scheuchzeria palustris ).

Other peat mosses, especially the magellan peat moss (Sphagnum magellanicum) and the reddish peat moss ( Sphagnum rubellum ), mostly intensely red in color, or the brown peat moss (Sphagnum fuscum) , on the other hand, colonize drier areas and the raised bults. They form together with other higher plants such as cranberry ( Vaccinium oxycoccos ), rosemary ( Andromeda polifolia ) and Heather ( Calluna vulgaris ), the Colorful Torfmoosgesellschaft ( Sphagnetum magellanici ). It is the most important peat-forming plant community in rain bogs. In the Atlantic lowlands, the bell heather peat moss lawn ( Erico-Sphagnetum magellanici ) was widespread as a peat-forming plant community . Characteristic are the bell heather ( Erica tetralix ) and the moor lily ( Narthecium ossifragum ) , which are widespread from the ocean to sub-ocean . In the eastern lowlands, these species are replaced by the swamp porst ( Rhododendron palustre ) and beyond Central Europe to the north by the cloudberry ( Rubus chamaemorus ) and the peat peat ( Chamaedaphne calyculata ). This plant community of Ledo-Sphagnetum-magellanici is interspersed with dwarf Scots pines ( Pinus sylvestris ). In Eastern Europe, the Magellan's peat moss (Sphagnum magellanicum) is being replaced by the brown peat moss (Sphagnum fuscum) . In the low mountain ranges , a peat moss lawn ( Pino mugi-Sphagnetum magellanici ) has developed , characterized by dwarf forms of the mountain pine ( Pinus mugo ) . In the subalpine level between 1,500 and 2,000 meters (Alps, Giant Mountains , High Tatras ) turf-rush-peat moss lawns ( Eriophoro-Trichophoretum cespitosi ) are developed.

The vegetation of the North American raised bogs is similar in its composition to the European plant communities, whereby the individual species are often replaced by other species of the same genera. For example, the species Ledum groenlandicum takes the place of the swamp porch . Eriophorum virginicum and Eriophorum vaginatum var. Spissum belong to the peat-forming plants of the cotton grasses . Species of the genera Gaylussacia , Gaultheria and Kalmia also appear among the dwarf shrubs of the North American rain bogs . In North Asia, the Siberian stone pine ( Pinus sibirica ) occurs on the plateaus. In the hollows can be found here Sphagnum dusenii and the Baltic peat moss ( Sphagnum balticum ) together with the bubble rush ( Scheuchzeria palustris ) and mud sedge ( Carex limosa ). The high moorland of Tierra del Fuego ( South America ) extends into the Antarctic climate and vegetation area. The bogs are mainly formed from the peat moss magellanic peat moss (Sphagnum magellanicum) and dwarf shrubs. The latter are made up of the dwarf Antarctic southern beech ( Nothofagus antarctica ), red crowberry ( Empetrum rubrum ) and the heather family Pernettya pumila . Instead of cotton grass, the rush family Tetronium magellanicum settles here .

Woods and bog forests

Trees such as downy birch ( Betula pubescens ), spruce ( Picea ), pine ( Pinus ) are also characteristic of living raised bogs in oceanic climatic regions. However, they are preferably found on the more drained slope slopes and on the ridge edges with a better supply of nutrients. On the plateaus there are mostly only a few trees with low growth (lack of mineral salts). At the edges of the water, the impact of waves leads to increased mineralization, which can offer more competitive woody plants, grasses and other plants a settlement opportunity. This also includes the blue pipe grass ( Molinia caerulea ) , which is feared in renaturation efforts . In drier, mineral salt-poor transition zones to raised bogs in continental climates and in higher mountain areas, quarry and bog forests such as mountain pine bog forests, birch bog forests or Carpathian birch forests can be formed. These are mostly poor-growing, low, sparse stands of pines or birches with a bushy undergrowth and a low-growing and gappy layer of herbs, mostly consisting of grasses and sedges and dwarf shrubs, but a well-developed layer of moss mainly made up of peat moss.


High-moor mother-of-pearl butterfly ( Boloria aquilonaris )
Female of the bog beetle cicada ( Ommatidiotus dissimilis ), short-winged form, lives on vaginal cottongrass exclusively in raised bogs.
Blue colored male of a moor frog during the mating season

Only a few groups of organisms can develop within growing rain bogs. There are no fish in acidic water, nor are there snails , clams , crabs or other animals that need a plentiful supply of calcium . Only specialists are able to exist and reproduce under the extreme site conditions. Similar to the peat moss, many animals are also colored red or dark ( melanism ), as an adaptation to the radiation intensity and the extreme temperatures. Another common phenomenon is dwarfism. Many animals, especially insects, are restricted in their diet to only certain plant species and / or plant genera of the raised bogs ( mono- to oligophagy) , so that they can only exist in this habitat.

Unicellular organisms

A typical group of animals Torfmoosrasen are the rhizopoda (rhizopods). These are wired amoeba (Testaceae), which can occur in high numbers of individuals. Thanks to the preservation ability of the shells, a so-called rhizopod analysis is possible, with the help of which the ecological conditions of a bog can be followed during its development history.

Insects and spiders

In summer, the numerous dragonflies in the high moor stand out. Dragonflies love moist locations, including both raised and fens. Some species are tied to the ecological conditions of the moors in all phases of life. Other species spend their youth here. The high moor mosaic damsel ( Aeshna subarctica ) is active from July to September and can only be found on high moor waters with peat moss swinging lawns. The males sunning themselves on tree trunks can be found especially on the mornings of sunny days. The males fly over the peat moss areas in search of females. Mating begins over the lawn and mostly ends in the vegetation. The female sticks the eggs into the peat moss.

The high-moor gloss flat runner ( Agonum ericeti ) is the raised bog specialist among ground beetles . It cannot be found outside of transitional and raised bogs. It lives between Bulten and Schlenken in the living raised bogs, and is sometimes found on raised bog regeneration areas. The species can only live on very acidic soils and is sensitive to changes.

The raised bog mother-of-pearl butterfly ( Boloria aquilonaris ) also depends on bogs in which the caterpillar's forage plant, the common cranberry ( Vaccinum oxycoccos ), grows. The caterpillar also partially feeds on young shoots of rosemary heather ( Andromeda polifolia ). In northern Germany the bell heather ( Erica tetralix ) is an important suckling plant for the butterflies.

The cicada fauna also has a large number of highly specialized, mostly monophagous raised bog species with a very narrow food spectrum. The bog beetle cicada ( Ommatidiotus dissimilis ) lives exclusively on vaginal cottongrass ( Eriophorum vaginatum ) of the open raised bog centers . Peat moss swinging lawns with narrow-leaved cottongrass ( Eriophorum angustifolium ) are preferred by the white-lipped green leaf hoppers ( Delphacodes capnodes ). The Schnabelried Zirpe ( Limotettix atricapillus ), which may have become extinct in the Weser-Ems area and feed on the White Schnabelried ( Rhynchospora alba ), lives in similar locations .

Where there is such a rich fauna of insects and mites, their enemies are not far either. They colonize the water, for example the very rare water spider , the peat moss such as the wolf spiders Pardosa sphagnicola and Pirata insularis , which are endangered or threatened with extinction in Germany, and the herbaceous layer and lower woody plants such as the marsh garden spider or the hunting spider Dolomedes fimbriatus . The bridge spider lives mainly in the edge hanging .

Amphibians, reptiles and birds

Amphibians , especially the moor frog ( Rana arvalis ), live and / or spawn in raised bogs. The bog lizard ( Lacerta vivipara ) and the adders ( Vipera berus ) are found among reptiles . The latter is often completely black in bog and is also known as the bog otter. Birds of low-tree raised bogs are teal and teal , black grouse , short-eared owl , curlew , wood sandpiper , southern golden plover and crane . The black godwit , redshank , skylark , whinchat and many other species live in the peripheral areas . The birds of the former raised bogs can now be found frequently in wet grassland, bog and marsh grassland. With the destruction of the moors, many of these species have declined dramatically and are now threatened with extinction or have already disappeared.


Mammals play a subordinate role in the moor fauna. The damp soil, which is not suitable for creating corridors, makes bog soils unattractive for mice, for example. The polecat , however, plays a certain role here, preferring to feed on frogs.

Drained bog

Bog birch forest on a drained raised bog

The use of raised bogs was almost always associated with or even required drainage . If drainage ditches are built in a raised bog, the biotope-determining factor changes fundamentally. The peatland eventually comes to a standstill. The bog's own water level sinks, the empty pores of the peat body collapse and the bog sinks. Oxygen from the air penetrates and starts the breakdown. The organic material is mineralized and the mineral salts stored in it are released.

Plants that need more mineral salts settle and displace the raised bog species. In north-west Germany, huge moor heaths ( Sphagno-Callunetum ) formed on dried up raised bog soils . If the drainage continues, the first trees will settle. Due to the transpiration of the trees, the moors continue to dry out. Finally, bog forests of different compositions emerge. It is mostly downy birch ( Betula pubescens ) and Scots pine ( Pinus sylvestris ) that make up these forests. In the low mountain ranges, Pinus sylvestris is replaced by the mountain pine ( Pinus mugo ). The Carpathian birch ( Betula pubescens var. Glabrata ) also occurs here and there . Typical of such bog forests are the pipe grass ( Molinia caerulea ) and bilberry and lingonberry ( Vaccinium myrtillus, V. vitis-idaea ).

The animal world is also changing. Due to the mineral salt enrichment and the increase in the small-scale structural diversity, the number of species increases. Moor specialists are being ousted. Such moors are home to a large number of animal species that no longer find a place in the cultivated landscape ( cultivated refugees ). Therefore, drained bogs are also valuable and of great importance for species protection .

Meaning and functions

The great importance of the raised bogs lies primarily in their property as a habitat for rare plant communities, plant species and animals. Several species such as the dwarf birch ( Betula nana ) were able to survive in raised bogs as relics of the post-ice age . In addition, raised bogs are retreats for endangered animal species that no longer find a place in the surrounding strongly human environment. After all, raised bogs are elements that define the landscape , as they take up large areas.

Landscape ecological functions

Raised moors have ecological functions in the landscape , which result from the special features of the water and nutrient balance described above as well as the climatic conditions of intact rain bogs. The formation of stocks through the removal of substances from the original cycle is of particular importance in the landscape budget. Due to the imperfect decomposition of the peat, carbon and other substances are fixed. The peat body and the peat moss serve as water reservoirs with a runoff dampening effect during heavy rainfalls and floods. Raised moors have a significant influence on the climate, because due to their high water content and the associated delayed warming at the beginning of the vegetation period, raised moors are viewed as cold habitats and thus influence the regional climate. In addition, bogs, whose peat bodies are flowed through and seeped through, can act as ion exchangers and hold back foreign substances such as pesticides or heavy metals. This filter effect represents a very important ecological landscape function in our increasingly polluted environment.

Natural and cultural-historical functions

Last but not least, raised bogs are of great scientific importance for the research of ecological systems and for natural and cultural history as archives for research into vegetation history as well as prehistoric and early historical research. This function results from the preservative effect in an acidic environment in the absence of oxygen and the effect of humic acids. Pollen has been preserved in the peat very well. With the help of pollen analyzes , the vegetation and climatic history since the last ice age could be reconstructed almost everywhere. Finds of pollen from cultivated plants give clues to the first settlements and the beginnings of agriculture. Furthermore, in European bogs numerous boardwalks were exposed and about 600 funeral remains found that as bog bodies are known. Moors are thus archives of cultural history since the last ice age ( moor archeology ).

Endangerment of rain bogs

Peat extraction in East Frisia

The greatest threat to rain bogs comes from peat extraction . In particular, the extraction of peat to produce garden soil has taken on a high priority today. The peat reserves in Central Europe are largely used up. This is why more and more peat is being imported from West Siberia and Canada, endangering the mostly still large and largely intact rain bogs there.

The threat to rain bogs from bog cultivation , i.e. the extraction of agricultural land, is only of minor importance today. Due to the physical properties of the peat (sagging and shrinking), intensive grassland and arable land on rain moor locations require repeated cultivation and intensive fertilization and are therefore not profitable.

Indirect influences such as mineral salt input through fertilizers from agriculture, pesticides , as well as nutrient, mineral salt and pollutant-loaded rainwater from domestic and industrial incineration plants are of greater importance. As a result, still intact rain bogs can be severely disturbed in their high bog-typical material balance.

Effects of rain bog use

In addition to the changed flora and fauna of the moors caused by the drainage and the associated loss of species, even more far-reaching consequences, regionally and globally, must be taken into account. Every drainage also means aeration of the peat. This sets in motion degradation processes that are summarized under the term “oxidative peat consumption”. Through this process, the function of the rain bogs as a fabric sink (see above ) is canceled. The substances that were previously fixed in the moor, i.e. disposed of, are now being returned to nature's cycle. For example, nitrogen that has been stored for thousands of years is released into the atmosphere in the form of ammonia (NH 3 ), molecular nitrogen (N 2 ), nitrogen oxides (NO x ) and nitrous oxide (N 2 O). The released nitrate (NO 3 - ) enters the water body in dissolved form and ultimately pollutes the groundwater and drinking water. Nitrous oxide, also known as laughing gas , even has global consequences, as it is involved in both ozone depletion and the greenhouse effect. These effects are reinforced by the release of carbon dioxide. Also, phosphorus is mobilized and charged in the form of phosphate (PO 4 3- surrounding waters) and contributes to the eutrophication in.

Protective measures

High moor renaturation area in the Emsland
Scheiden cottongrass in the renaturation area Goldenstedter Moor

The importance of the raised bogs was only recognized in the last few decades. The insight prevailed to at least protect the still existing raised bogs and regenerate them as far as possible. The protection of the remaining near-natural raised bog remains is all the more urgent, because raised bogs are irreplaceable habitats that cannot be restored in the foreseeable future due to their development over thousands of years. Today, peatlands in the broader sense are largely protected against interference and interference at national and international level. But economic interests are still in the foreground, so that the last rain bogs are still acutely threatened by complete destruction.

At the international level, the Ramsar Convention also applies to rain bogs. In February 1976 Germany joined the Ramsar Convention, an international treaty for the protection of wetlands. In Germany there are currently 32 designated wetlands with a total area of ​​839,327 hectares. These include the Wollmatinger Ried (1,286 ha), the Diepholzer Moorniederung (15,060 ha) and the Elbe-Weser triangle with the Ahlenmoor . But not all countries have signed the convention or taken the appropriate protective measures and designation of suitable areas.

Ramsar areas in Europe with rain bogs:

  • Region around Limbaži and Valmiera in northwestern Latvia with 5,318 ha
  • Lielais Pelečāres purvs in Latvia, 5,331 ha
  • Teiču dabas rezervāts, with 19,337 hectares the largest reserve in Latvia
  • Čepkelių raistas, reserve in south-east Lithuania with 11,212 ha, of which 5,000 ha are bogs
  • Thursley and Ockley Moore in England with 265 hectares
  • Waldviertel in Lower Austria with 13,000 ha

The implementation of the obligations entered into by the Ramsar Convention is carried out through several European directives. In Germany mainly through the Federal Nature Conservation Act and the nature conservation laws of the federal states . In Lower Saxony , formerly the federal state with the greatest number of raised bogs, around 32,000 hectares of rain bogs are under nature protection (Lower Saxony's Moor Protection Program). However, only 3,600 hectares are in a natural state. So far, around 6,000 hectares have been rewetted. A total of 20,000 hectares are to be renatured by 2020.

In Switzerland, since the adoption of the Rothenthurm Initiative in 1987, all moors of national importance have been placed under protection. All of the 550 remaining raised and transitional moors in Switzerland are protected by the raised moors ordinance of January 21, 1991 ( SR 451.32). They must be preserved in their entirety and there is a construction ban. In the protected areas, only agricultural activities on the previous scale and maintenance and regeneration measures are permitted. In many protected objects of national importance, however, the ecological quality declines. Buffer zones and regeneration are required . The FOEN supports the cantons with enforcement aids.

Efforts are currently underway to designate the Wassjuganmoor in western Siberia as a UNESCO World Heritage Site . One of the tasks of UNESCO is the administration of the world heritage of mankind, which is carried out by the sub-organization World Heritage Committee . The large Wassjuganmoor, the largest moor in the world with over five million hectares, is predestined for a world natural heritage area, because it is characterized by its globally unique macrostructures, which can only arise on such large moors.

Renaturation of raised bogs

Dam for water retention as a renaturation measure on partially pitted areas in the Hahnenknooper Moor
Rewetting with dead birch trees

The rewetting of drained raised bogs is the first, central step in renaturation. What is important and important in the renaturation of raised bogs is the watering with water that is low in mineral salts, i.e. rainwater. This can be achieved by first closing old drainage ditches with the help of dams. Furthermore, trees on the area must be removed because they take away the light of the moors, contribute to evaporation and thus to the loss of large amounts of water. Rewetting usually takes a few years. At the same time, the rising water level leads to the death of the unwanted vegetation. Over a few decades, natural conditions should then be restored. Raised bog plants should spread again. The long-term goal, that is to say in centuries, is ultimately complete regeneration. The raised bog regeneration is achieved when the wet bog area has become a living and peat-forming, i.e. growing, raised bog again.

Even partially peat bogs can be prepared under certain conditions in such a way that a renewed development or formation of upland bogs appears possible. First, the peat extraction areas, where a residual peat thickness of at least 50 centimeters has been preserved, is leveled. Then so-called polders, i.e. rain retention basins made of peat, are created and surrounded with peat dams. As in drained residual moors, rewetting, regeneration and possibly renaturation take place.

Today it cannot be decided whether a renewed moor growth is or will be possible. So far, none of the renaturation projects has matured to a point of regeneration. Nevertheless, a number of renaturation measures have shown to date that the conditions are quite moor-like. In particular, the increasing environmental pollution and the mineral salt enrichment of the rainwater could be antagonists of a positive moor development as well as a possibly changing climate.

This raised bog development takes place as a three-phase process, each with a different duration, via rewetting and renaturation for regeneration :

Raised bog development
Phase 1 Re-wetting for a few years

- short term

The pitted surface is prepared and leveled again. Large basins (polders) are created on large milled peat areas to retain precipitation. When the water level is high enough, the first peat moss and other plants (mostly narrow-leaved cotton grass) can settle. In degenerated raised bog remains, it is sufficient to close the drainage ditches to stop the bog from drying out further. Rainwater can be stored again. The rising water level leads to the death of the unwanted following vegetation.
Phase 2 Renaturation for a few decades

- medium term

It includes the restoration of near-natural conditions. Towards the end of the renaturation process, which takes a few years, the bog has become soaked with rainwater, and raised bog plants can spread again.
Phase 3 Regeneration for a few centuries

- long term

The raised bog regeneration is achieved when the rewetted bog area has become a living and peat-forming raised bog.

Cultural and contemporary history

Paula Modersohn-Becker : Moorgraben, 1900 to 1902

How people perceived rain bogs and rain bog landscapes has been handed down in poetry, literature and painting. While countless poems and paintings were dedicated to the forest, moors played only a comparatively subordinate role as an object of artistic representation.

The inhospitable nature of the large, uncultivated moors was uncanny for people well into the 20th century. They have almost always been described as gloomy, repulsive, inhospitable, enchanted, even deadly places. For these reasons, eerie legends and myths have been entwined with the moors since ancient times . Moors were seen as a place to stay for evil spirits. Strange appearances such as will- o'-the-wisps have reinforced these attitudes. These will-o'-the-wisps are explained by self-igniting swamp gases that are formed in bogs by certain bacteria and can escape through crevices. These will-o'-the-wisps have almost disappeared, because almost all moors have been changed in their natural water and matter balance due to drainage. Such associations were not associated with any other living space. Moors were impassable, it was difficult to traverse and one could get lost in the seemingly endless expanses. It was and is believed that one can sink into the moors, which is not inevitably the case. Only scour edges and larger accumulations of water are sometimes more profound and, in poor visibility (fog), are to be regarded as danger zones. The centers of intact rain bogs were always accessible, albeit under difficult conditions. In all ages people have had to cross moors. Where the size of the moor allowed, they were bypassed widely. If they were too big, billet dams were built and later more solid boardwalks . Certainly people got caught in bog and drowned. The finds of bog corpses prove, however, that these are rarely victims, but that they mostly died violently. In addition to the gloomy representations, there are also romantic, transfigured descriptions of the rain moor landscapes " [...] in which grandeur and beauty lived close together with the horror of a desolate wasteland. ".

After the planned and large-scale use of the moors had begun, representations were added that deal with the arduous life of the first peat colonists. The new farmers settled in the moor, who applied with the prospect of owning their own property and exemption from taxes and military service, had a hard time. The saying "Den Eersten sien Dod, the Tweeten sien Not, den Drütten sien Brod" (Death to the first, distress to the second and bread to the third) probably applied in all moor areas. Because of their inaccessibility, raised bogs were just good enough to resettle uprooted people and prisoners and exploit them in the service of the state. A bad chapter in contemporary history is the forced labor of prisoners in Emsland concentration camps , which went down in history in the song “We are the Moorsoldaten”.

Poetry and literature

In her poem “ Der Knabe im Moor ” from 1842, the poet Annette von Droste-Hülshoff describes the oppressive atmosphere of the moor landscape.

“Oh, it's gruesome to
walk across the moor, when it's teeming with heather smoke.
Like phantoms the fumes turn
and the tendril
crochets in the bush , Under every step a spring jumps,
When it hisses and sings from the crevice -
O scary to walk over the moor,
When the reed cracks in the breath!
What is rustling over on the Hage?
This is the ghostly digger Who forgives
the master the best peat;
Hu, hu, it breaks like a mad cow!
The little boy dodges. "

The botanist August Grisebach (1840–1879) describes the rain moor landscapes in a romantic and transfigured way (in Overbeck 1975):

“It was an endless expanse, in which no object rose above knee level and the horizon line was drawn far and wide through the moor itself. Velvet-green, olive-colored, rust-brown and blood-red moss cushions form the colorful pattern of the soft, swelling carpet, over which the foot was only able to stride with difficulty in the long run and with every step it squeezed water out of the giant sucking sponge. It was a landscape in which grandeur and beauty lived close together with the horror of a desolate wasteland. "

Also Rainer Maria Rilke deals with bogs and sets the arduous life of Moorbauern as follows literary order (in Succow & Jeschke 1990):

“In spring, when the peat-making begins, they get up when they light up and, dripping with moisture, mimicrying their black, muddy clothes to match the moor, they take them to the clay pit from which they shovel up the leaden moor soil. In the summer, while they are busy harvesting the grain and hay, the peat that has been prepared dries, which they bring into town in the autumn on barges and wagons. The loaded boat waits on the black water of the canal, and then they drive seriously as if with coffins towards the morning and towards the city, neither of which want to come. "

Sir Arthur Conan Doyle set his crime story "The Hound of the Baskervilles" in the moorland of Dartmoor .

Landscape painting

Paula Modersohn-Becker : Bog canal with peat barges, around 1900

In Worpswede , a small town in the Teufelsmoor near Bremen , around 1900 a number of painters had come together in an artist colony who, consciously turning away from academic painting, sought contact with nature and were inspired by it to create a new aesthetic that had never been seen before. Their role models were the French impressionists . The painters created a series of paintings that show the then strongly anthropogenically reshaped moor landscape of northwest Germany. The most important representatives of this first generation of Worpswede artists are: Heinrich Vogeler , Otto Modersohn , Paula Modersohn-Becker , Hans am Ende , Fritz Mackensen and Fritz Overbeck . The painting by Fritz Overbeck "Im Moor" (around 1900) shows different stages of dismantling of a raised bog. Fritz Mackensen's “Einsame Fahrt” or Hans Ende's “Weites Land” show peat barges and heathered moorland. The painting by Otto Modersohn "Autumn in the Moor" (1895) shows an impressive landscape experience.

Contemporary history

On August 27, 1933, the song Die Moorsoldaten was performed for the first time by concentration camp inmates in Börgermoor . It describes the depressing situation of the prisoners who had to dig peat with a spade as part of the forced labor and had to perceive the moor in a completely different way from this perspective:

"1. Wherever the eye looks,
moor and heather just all around.
Vogelsang does not give us any comfort,
oaks stand bare and crooked.

Refrain: We are the bog soldiers
and we move
into the bog with the spade !

2. Here in this desolate heather […]
3. Digging by the blaze of the sun […] "


  • M. Succow , M. Jeschke: Moors in the landscape. Origin, household, living world, distribution, use and maintenance of the moors. Thun, Frankfurt am Main 1990, ISBN 3-87144-954-7 .
  • H. Joosten, M. Succow: Landschaftsökologische Moorkunde. E. Schweizerbart'sche Verlag Buchhandlung, Stuttgart 2001, ISBN 3-510-65198-7 .
  • Heinz Ellenberg : Vegetation of Central Europe with the Alps from an ecological, dynamic and historical perspective. 5th, heavily changed and improved edition. Ulmer, Stuttgart 1996, ISBN 3-8001-2696-6 .
  • J. Eigner, E. Schmatzler: Handbook of high moor protection. Kilda, Greven 1991, ISBN 3-88949-176-6 .
  • Claus-Peter Hutter (Eds.), Alois Kapfer, Peter Poschlod: Swamps and Moors - Recognize, determine, protect biotopes. Weitbrecht, Stuttgart / Vienna / Bern 1997, ISBN 3-522-72060-1 .
  • H. Joosten: Think like a high moor. Hydrological self-regulation of raised bogs and their importance for rewetting and restoration. In: Telma. Hanover 23.1993, pp. 95-115, ISSN  0340-4927
  • F. Overbeck: Botanical-geological moor studies. Wachholtz, Neumünster 1975, ISBN 3-529-06150-6 .

Web links

Individual evidence

  1. GM Steiner: Types of Moors. In: Stapfia. Volume 85, pp. 5–26, PDF on ZOBODAT At the same time catalogs for Upper Austria. State museums. New series 35, 2005, section raised bogs, rain bogs - bogs fed by rainwater. P. 14 ff.
  2. ^ O. Bragg, R. Lindsay: Strategy and Action Plan for Mire and Peatland Conservation in Central Europe. Wetlands International, Wageningen 2003, ISBN 90-5882-018-1 .
  3. ^ KJ Nick, J. Blankenburg, R. Eggelsmann, HE Weber, D. Mossakowski, R. Beinhauer, J. Lienemann: Contributions to the rewetting of degraded black peat areas. (= Nature Conservation and Landscape Management Lower Saxony. Volume 29). Hanover 1993, ISBN 3-922321-66-6 .
  4. ^ HJ Weidemann: Butterfly - observe, determine. Naturbuch, Augsburg 1995, ISBN 3-89440-115-X .
  5. ^ E. Freese, R. Biedermann: Typhobionte and tyrphophilic cicadas (Hemiptera, Auchenorrhyncha) in the raised bog remains of the Weser-Ems region (Germany, Lower Saxony) . (PDF; 288 kB). In: Contributions to the cicada. Halle, 8.2005, pp. 5–28. ISSN  1434-2065
  6. Moore. In: bafu.admin.ch . Federal Office for the Environment, June 30, 2015, accessed on January 23, 2018 .
  7. ^ M. Hausmann, W. Kaufmann, W. Stock, C. Modersohn, G. Heidrich, B. Kaufmann, S. Salzmann, K. Schütze, K. Riedel, M. Trudzinski: Worpswede. A German artist colony around 1900. Galerie, Fischerhude 1986, ISBN 3-88132-139-X .
  8. Wolfgang Langhoff: The Moorsoldaten. Schweizer Spiegel-Verlag, Zurich 1935 (published in exile) (Mitteldeutscher Verlag, Halle 1986, ISBN 3-354-00041-4 )
This version was added to the list of excellent articles on April 29, 2006 .