|Area share||approx. 5% of the land surface|
|Ecological condition||> 60% original wilderness
~ 20% largely near-natural
|Land use||mobile (reindeer) grazing|
|biodiversity||very low (600–1000 species per hectare)|
|Biomass||very low (25–30 t / ha dry matter)|
|Representative large protected areas (only IUCN Ia, Ib, II , NP , WE and PP )||
Thelon (CAN) 52,000 km²
Tundra : climate diagrams
|Exposure to sunlight||<800–1100 kWh / m² / a (for the zone)|
Coldest month: below −40 ° C to above 0 ° C
Annual mean: below −20 to below 5 ° C
Warmest month: below −5 to above 10 ° C
|Annual precipitation||under 200 to over 1500 mm
(8-11 months of snow)
|Water balance||nival ( humid )|
|Growing season||30-90 days|
Tundra (also cold steppe ) is the generic term for the open land areas of the subpolar climatic zone . The term comes from geography and generally designates a certain type of landscape on the global scale . There are different definitions depending on the discipline, see section “Definition” .
Characteristic of the various forms of the tundra is an open, tree-free landscape (mostly) over permafrost , which, depending on the subtype, is dominated by lichens , mosses , grasses and deciduous dwarf shrubs .
From the perspective of Geobotany ( plant geography ), the Tundra is a natural vegetation type , which especially under the conditions of Tundrenklimas arises. In their erdumspannenden ( geozonalen ) expansion, the Tundra is among the vegetation zones . In addition, comparable plant formations occur worldwide in the alpine altitude range of the mountains, which can be assigned to the tundras as non- zonal vegetation types .
From an ecological point of view , the tundra is one of the largest possible (abstract) ecosystems that together form the biosphere . It itself is formed from typical biomes or ecoregions , which in turn are composed of the associated small-scale (specific) biotopes and ecotopes . These in turn subdivide the Earth-encompassing polar zonobiom or the polar / subpolar ecozone .
Spread and condition
The northern (arctic) vegetation zone of the tundra extends beyond the polar tree line in its maximum extent from about 80 ° north latitude (on the island of Spitzbergen ) to 55 ° (at James Bay in Canada). The southern (Antarctic) zone extends from 70 ° south latitude (in Palmerland on the Antarctic Peninsula) to about 45 ° (on the Crozet Islands in the Indian Ocean).
Due to the few subpolar land areas in the southern hemisphere, the tundra only makes up a tiny fraction of the total area there. "Real" tundra is found there only to a very limited extent on the edges of Antarctica and on some sub-Antarctic islands. The subpolar meadow and moorland areas of South Patagonia (also known as "Magellan Tundra"), the dwarf shrub heaths of the Falkland Islands and the sub-Antarctic meadows of the Crozet and Kerguelen Islands in the Indian Ocean and Macquarie Island in the South Pacific give way with one The milder climate and the lack of permafrost soils differ significantly from the typical tundra climate, although the vegetation is quite tundra-like in character. The assignment of vegetation is therefore inconsistent in the literature. Similar climatic conditions also require subpolar meadow and heather vegetation in southern Alaska and on the Aleutian chain of islands, which is therefore not a “real” tundra.
The tundras move towards the poles into the zone of ice and cold deserts and towards the equator (in the northern hemisphere) into the forest tundras . Temperate rainforest adjoins the tundra-like bogs of Patagonia .
The non-zonal mountain tundra, meadows and heaths occur worldwide in almost all high mountains above the tree line.
In relation to the potential natural vegetation , around 5% of the earth's land surface today is tundra. In fact, at the beginning of the 3rd millennium, over 60% of them are in a largely unaffected, natural state . These areas are almost uninhabited. Around 20% are still close to nature and have relatively little influence. However, these areas are mostly highly fragmented and are consistently changing (either through constant conversion into usable areas or through overexploitation ). At less than 20% the original vegetation cover was intensively changed and shaped by anthropogenic landscapes . In these areas, near-natural tundra landscapes are only to be found in small relics.
The tundra is the result of high selection pressure due to hostile environmental conditions: Plant growth is mainly influenced by the extreme climatic conditions and (usually) by the permafrost soil . In summer, the waterlogging over the frozen subsoil leads to very large temporary wetlands . This interplay of frost and moisture is also the cause of the different types of bogs and soil structures in the tundra landscapes. The plants of the tundra are characterized by low growth forms and great resistance to frost. Stock-forming plants are mosses and lichens , grasses , alpine herbs and deciduous dwarf shrubs . The branches of these shrubs often stay close to the ground ( trellis growth ), the rougher the microclimate at their location.
The earth's tundras lie in the sub-polar climatic zone and are therefore usually characterized by very cold climates with long, cold winters and short, cool summers. In the coldest month, the average temperatures drop below −17 to −40 ° C. In Tierra del Fuego and Patagonia, temperatures remain close to freezing point, while in the mountain tundra of Siberia they can also drop well below −40 ° C. In the "real" tundras there is eight to eleven months of snow. The warmest month is between −6 and 6 ° C in the polar tundras and well above freezing point up to 16 ° C in the mountain tundra at warmer latitudes. However, maximum temperatures of 25 ° C are also possible in high latitudes. The long-term mean temperature in the polar tundra is ± 0 to −18 ° C on average, while in the other areas it can vary up to 7 ° C and down to −22 ° C. For the polar tundras, there is also a very low level of solar radiation , which makes it difficult for plant growth , which is, however, caused by the midnight sun in midsummer . T. is compensated.
With averages below 200 to 600 mm, the total annual rainfall is low to moderate. In the oceanic mountains, values of over 1500 mm are also measured. Since they mainly fall as snow, the climate is also known as nival . The long frost period and the low temperatures lead to a low evaporation rate , so that the water balance on the ground is completely humid (very humid) despite the low amounts of precipitation .
The growing season is short to very short at 30–90 days. However, this means that the flowering time of many plants, which takes place elsewhere at different times, occurs simultaneously in the tundra climate.
Most of the soils in the tundras belong to the permafrost soils . Are there organic soils, ie in particular the existing Moostorfen from tundra bogs, they are according to the international soil classification system World Reference Base for Soil Resources (WRB) to Histosolen . (Also bogs without permafrost belong to the histosols, but these are rare in the tundra.) Are the permafrost soils mineral soils, e.g. B. in rocky or sandy terrain, they are called cryosols . Leptosols are also found to a much lesser extent under Alaska's and northern Europe's mountain tundra . These are shallow soils on solid rock or very skeletal soils.
There is very little litter and decomposition is very slow. This is the reason for an enormous accumulation ( accumulation ) of raw humus in the flat tundras and for very large, quite uniform ecosystems. On shallow slopes, the soil often flows ( solifluction ).
The restless ground relief, which is often characterized by knolls and hollows or walls arranged like a net or ring, is extremely typical of the highly polar tundra landscapes. These are either polar bog types (aapamoore, polygonal bog) , palsas or pingos or, in drier areas, so-called frost pattern soils . Essentially, the thawing and thawing of the ground above the permafrost leads to these unusual structures.
Due to the abiotic factors mentioned above , the amount of biomass available is very low (25–30 t / ha dry matter). Five to six t / ha are created every year.
Only 0.4% of all vascular plants on earth live in the Arctic. In most areas the entire vegetation (sometimes up to over 90%) is made up of less than 10 species. In addition, the distribution of almost all species living there is not limited to the tundra. Plant density and diversity decrease towards the poles. The following plants are typical of the tundra:
Mosses , lichens ; extensive sour grasses , significantly less sweet grasses ; Clubmosses , Betula nana , plumbaginaceae , ferns , melanthiaceae , Bellflower Family , buttercup family , Ericaceae , Polygonaceae , Asteraceae , Brassicaceae , Poppy Family , Onagraceae , Pink family , Borage Family , rose plants , horsetails , Pea , Broomrape family , Saxifragaceae , lentibulariaceae , plantain plants , shrub-like and dwarf willow family .
Before humans brought in a handful of neophytes , only two flowering plants grew in the whole of Antarctica : the Antarctic Schmiele ( Deschampsia antarctica ) and the clove plant Antarctic Perlwort ( Colobanthus quitensis ). The vast majority of the Antarctic tundra is made up of mosses and lichens. The other areas of the sub- ant arctic tundra (especially Tierra del Fuego , the Falkland Islands , South Georgia , Kerguelen , Crozet Islands ) have much less dwarf shrubs and overall a much lower biodiversity than the sub-arctic tundra.
The following mammals are typical inhabitants of the polar tundra: polar bear , musk ox , arctic fox and arctic wolf . Are up in the Waldtundren spread (Russian) Tundra Wolf, Arctic hare and arctic hare . The following mammals are distributed from the tundra to the boreal coniferous forests: lemming , brown bear , various subspecies of the wolf ( Mackenzie wolf , Eurasian wolf), wolverine and reindeer ( called caribou in North America ). Typical of the tundras and highland steppes of the mountains of Central Asia are the yak and the snow leopard .
Typical tundra birds: ducks , hawks , geese , mergansers , plovers , common raven , cranes , Arctic tern , gulls and skuas , rough-legged buzzard , snow bunting , snowy owl , ptarmigan , Lapland Bunting , Golden Eagle , Ruddy Turnstone , beach runners , divers kinds, different bird families: Grebes (Podicipedidae ), Loons (Gaviidae), tundra swan
The fauna of the sub-Antarctic tundras is also significantly poorer in species than that of the Arctic. All of the larger land-dwelling animals in Antarctica are birds, especially penguins , petrels, and sheaths . Only in the Magellanic Tundra of Tierra del Fuego do a few mammals such as the guanaco , the Andean jackal or crested rats occur. The Falkland Islands were home to a single native land mammal, the Falkland Fox , which was extinct in the 19th century. On many sub-Antarctic islands, a. Rabbits, rats, dogs and cats introduced, e.g. T. cause great damage to the native fauna. The reindeer was deliberately settled in South Georgia, on the Kerguelen and on Tierra del Fuego. The population of around 3,000 animals in South Georgia will be completely exterminated from 2011 to 2015 in order to prevent further damage to the sensitive tundra vegetation.
The polar and sub-polar regions are among the most sparsely populated landscapes on earth, although humans penetrated the Arctic during the last Ice Age. Indigenous peoples still live in the tundras, which have remained close to nature , whose lives have always been shaped by the peculiarities of their land and who are still dependent on the largely intact ecological conditions of their ancestral home. The following selection therefore only takes into account those peoples in which at least some parts of the population have not yet fully adopted modern Western culture , whose economic practices are predominantly extensive and traditionally sustainable , and whose cultural identity still has a great - often spiritually anchored - bond with contains their natural habitat.
However, this should not hide the fact that the original "natural" way of life of all these people has already changed significantly due to increasing mechanization, changed dependencies due to the influence of the western lifestyle or different assimilation policies and decreasing traditional knowledge. There are many promising approaches to preserving or reviving the traditions. However, this mostly relates to language, material culture, customs or religion. Only in a few cases do these endeavors have a cultural and ecological background in order to promote the preservation of traditional farming methods in the tundra.
The original inhabitants of the Eurasian tundra are (from west to east) the Sámi the Fennoscandian mountains -type regions, the Nenets , Nganasans , Evenki - all the cultural complex are expected "Siberia"; as well as the Jukagirs , Chukchi and Koryaks who form the cultural area "Paleo-Siberia". The North Eurasian Tundrenvölker were once mostly reindeer - nomads . Even today, reindeer herding plays a more or less important role for most of the peoples mentioned. The Nenets have so far been able to preserve their traditionally adapted way of life best.
The native inhabitants of the great tundras of North America and Greenland are the Eskimo peoples (cultural area "Arctic") - including the Inuit - who still live from hunting (especially on marine mammals). In the mountain tundra of Alaska and Canada, some Athabaskan Indian tribes hunt , above all the Kutchin , who still live primarily on the caribou. However, the residential area of this tribe is in the forest tundra . For the majority of the above-mentioned ethnic groups , hunting and gathering is only a sideline. The indigenous inhabitants of the sub-polar, tundra-like areas of southern Alaska are the Aleutians .
Use, development, endangerment and nature conservation
Agricultural cultivation is not possible in the tundra due to the climate. Large-scale use has always been limited to mobile reindeer grazing : formerly exclusively nomadic, today often semi-nomadic and using modern methods. In northern Europe in particular, but also in parts of northern Russia, the proportion of reindeer husbandry in subsistence farming is steadily declining in favor of market-oriented animal production . The emerging economic competition often leads to an increase in herds with the risk of overgrazing . Usually one to seven reindeer per square kilometer is the limit, but today it is often exceeded.
Beneath the tundra there are rich mineral resources, the extraction of which, apart from oil and natural gas, can be described as "selective" given the enormous size of the areas. The gas and oil production - z. B. on the coast of northern Alaska ( Prudhoe Bay oil field ) or in northern Siberia ( Urengoy gas field ) - is, however, associated with large-scale disturbances and far-reaching risks for the sensitive ecosystems. Soils and vegetation are so sensitive that even seemingly minor wounds from the climatic conditions become increasingly pronounced over time (so-called thermokarst ).
In the whole of Antarctica, no raw material extraction may take place until 2048 within the framework of the “Antarctic World Park” .
Global air pollution has acidified water in some areas of the tundra and damaged the delicate lichens that are an essential food source for many animals. The man-made thinning of the ozone layer leads to increased ultraviolet radiation , which in turn can lead to direct damage to plants and animals.
The greatest threat to the tundra results from global warming , which is well above average in the high latitudes of the north. The tundra will become overgrown and eventually - albeit with a long delay - become forest, so that one day this type of vegetation and its typical inhabitants will almost completely disappear.
- see also → animated map "Shifting climatic zones" .
The thawing of permafrost is already causing considerable damage to nature, but also to roads and buildings. In the course of time, large amounts of methane may be released, which could drastically accelerate the warming. It can be observed more and more frequently that the reindeer herds are suffering from the effects of warming. Warm weather phases in summer, which lead to a weakened immune defense, are the minor problem. A thaw in winter causes a layer of ice to subsequently form on the vegetation, which makes it much more difficult for the animals to access their food.
According to the IUCN , around 15% of the total area was under protection in 2003. Around 74% of this comes from North America.
The exemplary large protected areas mentioned in the info box each contain the largest possible proportion of the tundra vegetation type. In addition, these are exclusively areas in which the preservation (or restoration) of a natural state that is as unaffected as possible is a priority and which can be viewed as strictly protected in an international comparison.
The global vegetation type tundra must be seen as a generic term for a large number of smaller plant formations , biomes and ecoregions , which can be further subdivided down to the level of the biotopes in a different number of stages:
Further classification according to plant formations
According to similar appearances - and therefore essentially without considering the specific species inventory - the tundras can be further subdivided as follows: (This subdivision is based on the names of Josef Schmithüsen )
Highly polar lichen u. Moostundra - 10 to 80% plant
- Lichen tundra - predominantly occupies sandy soils and loves dry locations
- Moostundra - occurs on moist soils
Low polar dwarf shrub u. Meadow tundra - over 80% plant
- Dwarf (Arctic) trawler tundra
- Sub-Antarctic hard cushion formations - the West Antarctic Islands
- Tundra Moor from - moss , cotton grass and sedge consisting
- Meadow tundra - with Schmielen , fescue and riding grass ; In some places crowberry , bearberry and also dwarf birch mix with the grass; Meadow or lawn tundra grows mainly on loamy soils in the oceanic variant of the subpolar climate
Mountain tundra / azonal alpine mats u. Heathens
- Mountain tundra - Swedish Fjäll , Norwegian Fjell , Icelandic Fjall , Finnish Tunturi is the name of the mountain tundra in Northern Europe
- Alpine Matten - the meadow tundra above the tree line in the mountains
- Mountain vegetation above the tree line - mainly dwarf shrubs
- Hard and thorn cushion mountain formations - the middle Andes
Tundra- like formations of the sub-polar region
- Subarctic meadows and heaths - on the Aleutian Islands and in southern Alaska
- Sub-Antarctic dwarf shrub heather - mainly on the islands of the South Atlantic
- Sub-Antarctic meadows - mainly on the islands of the southern Indian Ocean
- "Magellan-Hochmoor" - on the southernmost islands off Tierra del Fuego
Classification according to biomes / ecoregions
The further subdivision leads from the global view to the regional scale level . At this level, the entire ecosystem is primarily considered and not just the vegetation. One speaks of the biomes and / or ecoregions .
The environmental foundation WWF USA has carried out an exemplary global classification according to ecoregions. The delimitation of these regions is based on a combination of different biogeographical concepts. They are particularly well suited for the purposes and goals of nature conservation .
According to the WWF categories, the term tundra is used for one of 14 main biomes ("major habitat types"), which roughly corresponds to the polar zonobiom . In terms of these main biomes, the cold desert is counted as part of the tundra, but not the azonal mountain tundra. 37 ecoregions (“Ecoregions”) subdivide this main biome.
- Georg Grabherr : Color Atlas of Earth's Ecosystems. Ulmer, Stuttgart 1997, ISBN 3-8001-3489-6 .
- Richard Pott : General Geobotany . Berlin / Heidelberg 2005, ISBN 3-540-23058-0 , pp. 353-398.
- J. Pfadenhauer, F. Kötzli: Vegetation of the earth. Springer Spectrum, Heidelberg 2014. ISBN 978-3-642-41949-2 .
- The individual types of vegetation, biomes and ecoregions, as well as their zonal equivalents, vegetation zones, zonobiomes and ecozones, are not congruent! Different authors, different parameters and fluid boundaries are the cause. The article Zonal Models of Biogeography provides further information . An animated map display illustrates the problem in the Geozone article .
- The percentages mentioned are (in part) averaged values from various publications. The deviations are unavoidable, since in reality there are no clear boundaries between neighboring landscape types, but only more or less wide transitional spaces.
- The choice of colors has been changed to make it easier to see on the original "Vegetation Zones" map.
- Information according to the reference soil classification of the World Reference Base for Soil Resources (abbreviation WRB)
- The WWF ecoregions can extend into neighboring vegetation zones due to the perspective - taking into account the potentially occurring plant and animal species. The pure consideration of the plant formations is therefore not used here!
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- averaged value from extensive research and comparisons in relevant specialist literature → see the respective description / sources of the files listed below : Vegetationszonen.png , FAO-Ecozones.png , Zonobiome.png and Oekozonen.png . Compiled and determined in the course of creating the aforementioned maps for Wikipedia → see also: Tabular overview of various landscape zone models and their proportions (PDF; 114 kB)
- Average value from extensive research and comparisons in relevant specialist literature → see description of the file : Wildnisweltkarte.png . Compiled and determined in the course of creating the aforementioned map for Wikipedia
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