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Alpine tundra is a type of natural region or biome that does not contain trees because it is at high altitude. The high altitude causes an adverse climate, which is too cold and windy to support tree growth. Alpine tundra transitions to subalpine forests below the tree line; stunted forests occurring at the forest-tundra ecotone are known as ''Krummholz''. With increasing elevation it ends at the snow line where snow and ice persist through summer. Alpine tundra occurs in mountains worldwide. The flora of the alpine tundra is characterized by dwarf shrubs close to the ground. The cold climate of the alpine tundra is caused by the lack of greenhouse effect at high altitude, and is similar to polar climates. == Geography == Alpine tundra occurs at high enough altitude at any latitude. Portions of Montane grasslands and shrublands ecoregions worldwide include alpine tundra. Large regions of alpine tundra occur in the Himalayas in Asia, American Cordillera in North and South America, the Alps, the Scandinavian mountains and Pyrenees of Europe, the Caucasus Mountains, the Rift Mountains of Africa, and a large portion of the Tibetan Plateau. Alpine tundra occupies high-mountain summits, slopes, and ridges above timberline. Aspect plays a role as well: the treeline often occurs at higher elevations on warmer equator-facing slopes. Because the alpine zone is present only on mountains, much of the landscape is rugged and broken, with rocky, snowcapped peaks, cliffs, and talus slopes, but also contains areas of gently rolling to almost flat topography. With limited access to infrastructure, only a handful of human communities exist in alpine zones. Many are small and have heavily specialized economies, often relying on industries such as agriculture, mining, and tourism. An example of such a specialized town is La Rinconada, Peru, a gold-mining town and the highest elevation human habitation at . A counterexample is El Alto, Bolivia, at , which has a highly diverse service and manufacturing economy and a population of nearly 1 million. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Alpine tundra」の詳細全文を読む スポンサード リンク
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