Friday, 22 May 2009

The Tundra Biome

The Tundra Biome (Rus:Tundra - Arctic hill)

The word 'tundra' means 'North of the timber line'. Tundra biomes lie north of timberline or 60o N latitude between the Arctic ocean and the Coniferous forests. It covers about 8 x 106 sq.km area (8 million km2) extending across North America, Europe and Asia.

There is no tundra biome in the Southern hemisphere.
Characteristic features of tundra biome are:

a) Ground surface is spongy, uneven as a result of freezing and thawing. This is because the plains of tundra are covered with snow, ice and frozen soil most of the year (permafrost).
b) Extreme cold climate with temperature ranging from -30oC to -40oC in winter.
c) Highest summer temperature is only about 10o C , only for a very brief period. During this time upper 10 - 20 cm deep surface region melt forming ponds, marshes and bogs in the depressions on terrain plain
d) Annual precipitation (mostly as snow) is below 25 cm.

Vegetation in tundra is very sparse. Hence, it is also called 'arctic desert'. It exhibits very low species diversity.
a) Biome is virtually treeless and is comprised of only Lichens (Cladonia - Reindeer moss) and Mosses (Sphagnum - Peat moss) forming the main vegetation.
b) Other plants growing are sedges, heaths, grasses, dwarf birches (Betula) and dwarf willow trees (Salix).
c) Plants are mostly shallow rooted and they often possess xerophytic adaptations.
d) Bilberries, dwarf huckleberries, low flowering herbs also grow in tundra.

a) No amphibians and reptiles are found.
b) Insects like biting flies, dipteran flies (black flies), mosquitoes etc are found here.
c) Migratory birds like water fowls are seen in summer. Other birds found here are snow - owl, snow - grouse (ptarmigan) etc.
d) The caribou, musk ox, arctic hare, arctic fox, lemming, polar bear and weasels are the mammalian residents of tundra. Some of them hibernate in winter in caves and others migrate to coniferous forests.

Productivity of tundra is estimated to be 200 k cal/m2/year. Recovery from any disturbance is very slow in tundra as it is a very delicate and fragile biome.
Tundra food chain...

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