The word “tundra” comes from a Lapp word, meaning “barren land”. The area is flat, with scarce vegetation and virtually no rises: a cold desert. The climate of the tundra depends on the region being either oceanic or mainland. For instance, in the European tundra, which is heated by the Gulf Stream, the land is unfrozen for many months, while the Canadian mainland tundra is always frozen. In Europe, the tundra begins at 7°N latitude, while in eastern Canada is begins at 55°N. During the long winter, the monthly minimum temperatures never drop below -10°C in the European tundra and can reach -30°C in Alaska. In eastern Siberia, the average winter temperature can reach -50°C. Since the sun does not rise in winter, the tundra spends several months in long, cold darkness. Conversely, during the summer the sun is always, or almost always, above the horizon with no real nights. The solar energy that reaches the ground is in any case little, since the sun stays very low on the horizon. It ensues that the water trapped in the soil freezes down to many metres, forming a layer of hard soil, the surface of which thaws in summer only. The frozen soil of the tundra is called permafrost (from the English permanent frost). Evaporation is very low, therefore, even if it rains very little; nevertheless, the melting of the upper layers of soil form large wet areas during the Arctic summer.

The Tundra in the world
The biome of the tundra covers the northernmost lands of Europe, Siberia and north America. Overall, the tundra covers 5% of lands above sea level. Some areas of tundra can also be found at the southern end of south America. In the Austral hemisphere, large expanses of perennial ice cover Antarctica; mosses and lichens grow, however, in some very small areas along the borders of the mainland.

The mountains of the temperate areas - above 2.000 metres a.s.l. - do not have trees either, because of the cold, so they look like the tundra. 

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Plants of the tundra
The vegetation of the tundra is almost entirely composed of perennial plants, came phytic plants (cushion-like plants) and hemicryptophytic plants (perennial herbaceous plants). Cushion-like plants include Ericaceae and saxifrages, while hemicryptophytic plants include sedges. There are no forest trees at all. Shrubs, birches and willows are few and small, to resist frost and strong winds. Mosses, rushes, graminaceous plants and peat mosses (a type of moss which has adapted very well to live in swampy areas) grow in wet areas, where the land is soaked in water. 

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Animals of the tundra
Despite the cold temperature, the tundra is inhabited by a lot of animal species. Many animals migrate to avoid the colder months. Others have developed, instead, different systems to defend themselves from the cold, through which they can survive in the tundra even during the long, cold winter night. In the tundra, animals cannot hibernate since the frozen soil cannot be dug up to make shelters or tunnels and because the warm season is too short to provide enough food to stock. 

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Birds of the tundra
The birds of the tundra are mostly migrant birds. Some of them, such as the greater willow chicken, move short distances away, while others travel for thousands of kilometres. The Arctic tern travels 36 thousand kilometres to reach the northern tundra from Antarctica! The goose is perhaps the most typical bird of the tundra. Many different species come here to breed after spending the cold months in the Mediterranean, Mexico, Africa or in the south of the United States. In summer, wet areas are the ideal place for many species of insects, that spend the winter as eggs. 

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The origin of tundra
The tundra as it looks today seems to have appeared on earth just two million years ago, before the succession of ice ages and following a general and lengthy cooling of the earth. The typical species of animals of plants that can be found in this biome must have come from high mountain areas. These organisms found a favourable habitat in the tundra, because it was like their native one. 

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