Toundra is a Russian term of origin which indicates the circumpolar vegetable formation which succeeds towards north the Taïga. Because of localization of the emerged grounds, the tundra exists practically only in the northern hemisphere. The tundra is also the denomination of the one of the 14 large Biome S terrestrial because of its ecosystem which has as a characteristic the existence of a single vegetable layer: a low layer made up of herbaceous and suffrutescent. It forms a circle around the pole of more than 8 million km ² is 6% of the emerged grounds.

Climate

The hard climatic conditions are marked by a length Hiver of freezing and a vegetative short period - generally 3 months during which the average temperature does not exceed 10°C. The Précipitation S, variables, in general do not exceed 600 mm per year, which gives a rather dry climate. Water falls primarily in the form of Neige. Lastly, the wind there is generally violent and names blizzard.

It is in the zone of the tundra that one meets the Pergélisol S, of the grounds which thaw out only on the surface. They are young and thin because few organic matters settled there. They thaw out partly during the summer. One speaks about Mollisol.

Biocénose

Flora

The flora of the tundra is very restricted compared to zones like the Mediterranean basin. South in north, one meets moors with shrubs of the family of the Salicacée S with many herbaceous species of Saule S dwarves, moors where still some trees like the Bouleau X are, then lawns with Cypéracée S and Joncacée S, finally of the zones where the vegetation is represented more only by foam S and Lichen S (certain soups by the reindeers). All these plants have a growth slowed down by the extreme climatic conditions.

The vegetative short period is however sufficient to attract many migratory birds (Eider, Bernache, Snow goose, etc) and to make of it an intense zone of animal life and reproduction.

Fauna

Fauna is diversified little but adapted very well to the living conditions. It generally carries a thick fur or plumage and white in winter as well as a large layer of grease to protect itself from the cold.

The Owl harfang and the grouse are sedentary birds which succeed in resisting the climatic conditions. Herds of large ruminants exploit also the tundra and migrate according to the food resources. One can quote the caribou S in North America, the Renne S in Eurasia, the musk oxen. The carnivorous are represented by the Polar bear S, the wolves or the arctic foxes. Part of their food is consisted small Rongeur S called Lemming S.

The court be boreal is also the occasion of the development of insects like the Moustique S.

Biomass

The biomass of this environment is very weak because the speed of slow growth of the plants. It represents approximately 5 tons per hectares and is located in the Système racinaire.

Biogeographic equivalences

In the moderated zones, the equivalent of the tundra can find in mountain with the alpine stage. However, the plant species and especially animal are quite different.

Simple: Alpine will tundra

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