Tundra
Tundra is a biome where the tree growth is hindered by low temperatures and short growing seasons.There are three types of tundra: Arctic Tundra, Alpine Tundra, and Antarctic Tundra.

Arctic tundra occurs in the far Northern Hemisphere, north of the taiga belt. The Arctic tundra is a vast area of stark landscape and is frozen for much of the year. It is impossible for trees to grow. Instead, bare and sometimes rocky land can only support low growing plants such as moss.
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Antarctic tundra occurs on several Antarctic and subantarctic islands, including South Georgia and the South Sandwich Islands. Antarctica is mostly too cold and dry to support vegetation, and most of the continent is covered by ice fields. In contrast with the Arctic tundra, the Antarctic tundra lacks a large mammal fauna, mostly due to its physical isolation from the other continents.
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Alpine tundra is an ecozone that does not contain trees because it has high altitude. Alpine tundra occurs in mountains worldwide. Alpine tundra is distinguished from arctic tundra, because alpine tundra typically does not have permafrost.
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http://en.wikipedia.org/wiki/Tundra