At the transition from the steppe region to the deciduous forest zone, there is a zone known as the forest steppe , in which the grass steppe near water bodies and on permeable soils is interspersed with forest islands. (The tropical vegetation forms sometimes referred to as "forest steppe" in older literature , however, are savannas .)
Steppes can be classified as follows according to the reasons for their formation:
- Primary steppe : This type is climatic and arises where there is a dry large climate with precipitation below 250 millimeters per year. The soils on which they arise can be deep and rich in nutrients and make excellent arable land if they are artificially irrigated. The former primary steppes in Ukraine , which exist above Chernosemen , are now often used as agricultural land.
- Secondary steppe : These were created on wooded sites through human clearing and use as pasture for the livestock of humans. One example are sub-areas of the Puszta that would be naturally forested, but in some regions the Puszta was primarily forest-steppe and steppe.
Substrate steppes exist where the soil does not allow high vegetation :
- There are rock steppes where the rock reaches just below or to the surface.
- Serpentine vegetation arises from ultrabasic rocks, which presumably inhibit plant growth through the excretion of toxic heavy metals.
- Gravel steppes arise over gravel deposits .
- Loess steppes consist of loess , a sediment that was transported and deposited by the wind during the cold periods.
- Sand steppes arise over sandy soils .
- Salt steppes form over salty soils. This can be sodium chloride , but also other salts such as sodium sulfate .
The temperate steppes include:
- the Eurasian steppe , which extends from Burgenland over the Puszta in Hungary and Bărăgan in Romania to eastern Mongolia .
- Parts of the Gobi semi-desert
- the Prairies and Great Plains in North America
- the pampas in South America
- Part of the outback in Australia
- the high country of New Zealand
- the Veld in South Africa
Another type of landscape, the tundra, is known as the “cold steppe” .
Features of the steppe
A steppe is an open, semi-arid, treeless grass landscape of the temperate zone . The vegetation is limited by a lack of water. In Eurasia , the steppes in the interior of the continent are located a great distance from the oceans , where the annual rainfall is severely limited ( continentality ). The steppe areas in North and South America arise from the lee position of the areas. Due to the seasonal distribution of precipitation , the vegetation season is often interrupted by summer drought or winter cold. The vegetation phases are only in spring and autumn .
As scientists from Lund University have established, the earth's steppes and savannahs, along with the tropical rainforests, are of great importance as carbon sinks and thus for the global climate. Around a third of anthropogenic carbon dioxide emissions are absorbed by the grasslands.
The formative plant communities of the steppe consist of grasses. You will also find mosses and lichens , but also lower shrubs such as the heather family and isolated forest islands in favorable locations. Originally, most of the cereal crops were steppe dwellers.
Although most precipitation falls in the steppe in the summer months, the plants have more water available in the other seasons. This is related to the fact that evaporation is very high in summer . But that doesn't fully explain the extent of these grasslands. Fire, intentionally started by humans or caused by lightning strikes, may play a role. In the North American steppes, the large herds of bison probably prevented the emergence of forest .
Animal species typical for steppes are z. B.
- the saiga (a species of antelope) in Asia,
- the pronghorn and prairie bison in the North American plains or
- the ancestral form of the lama, the guanaco (Lama guanicoe) in the pampas of South America .
In the steppe of the temperate zone, agriculture is practiced on fertile soils such as phaeozemes or chernozemes , mostly as irrigation farming . Because of the short growing season, mainly corn and wheat are grown. Large parts of the world's wheat production come from the steppes of North America and Eurasia. The more arid the steppe's climate, the more uncertain the yields.
Where the water conditions only allow extensive agriculture , mobile animal husbandry dominates . Farm animals are z. B. Buffalo , cattle , horse , sheep , goat , camel and yak . In addition, traditional nomadic cattle breeding can still be found in some areas of the Eurasian steppe .
- Hansel, Bernhard : The steppe and the Carpathian basin in the field of tension between nomadic and sedentary life forms, in: The Carpathian basin and the Eastern European steppe. Prehist. Arch. Südosteuropa 12, 1998, 7-18.
- Hansel, Bernhard: The steppe and the south-eastern European subcontinent. Nomadic incursions and transhumance , in: Civilization Grèque et Cultures Antiques Péripheriques - Hommage à P. Alexandrescu (Bucharest 2000) 31–43.
- deutschlandfunk.de , Dossier , June 17, 2016, Tom Lessokallow: The end of the nomads or the emergence of an ecological catastrophe
- payer.de: Materials for forest science. ... 7. Eg VII: Winter cold steppes, semi-deserts and deserts
- Friedrich Ehrendorfer : Geobotanik in: Textbook of botany for universities, founded by E. Strasburger, F. Noll, H. Schenck, A. F. W. Schimper. 13th edition, Stuttgart 1978, p. 979
- Luise Schratt-Ehrendorfer: The flora and fauna of the steppes of Lower Austria: Flora and vegetation, site diversity and endangerment , in: Heinz Wiesbauer (Ed.): The steppe lives - rock steppes and dry grasslands in Lower Austria , St. Pölten 2008, ISBN 3-901542-28 -0
- Viktiga savanner . In: Sveriges Natur , No. 106 - 415, Member the Swedish Nature Conservation Association, Stockholm, September 2015, , p. 16.