Tundra is a term most often used for the cold, dry, treeless lands of the Arctic. These lands have a cover of ice and snow for most of the year. They include northern parts of North America, Europe, and Asia, and much of Greenland. People sometimes use the term tundra for treeless alpine (mountainous) regions and for lands in and around Antarctica.
Most tundra areas lie north of the Arctic Circle. They have continuous daylight in midsummer and continuous darkness in midwinter. Tundra regions experience long, often bitterly cold winters. The warmest summer climates average between 32 and 50 °F (0 and 10 °C).
Scientists classify tundra as a biome—that is, a community of animals, plants, and other living things that covers a large geographical area. The tundra biome lies north of the tree line, meaning forests will not grow there. Small clusters of shrubs, usually birch or willow, sometimes occur within tundra regions. But these appear only in a few areas, including parts of the Labrador coast in Canada. Most tundra regions receive little snow or rain. The low temperature of tundra air masses (huge volumes of air) means they contain little water vapor. Many tundra regions are so dry, people often call them Arctic deserts.
The land beneath the tundra surface normally remains frozen all year. This frozen soil, called permafrost, often extends hundreds of feet or meters down. Permafrost is seldom continuous and contains many unfrozen zones, particularly beneath lakes and ponds. In warmer regions, the tundra surface thaws during summer and enables plants to grow.
Many distinct landforms appear in a tundra. Small conical hills called pingos form in numerous low-lying areas, often from the freezing of spring water. The melting of permafrost may create temporary thaw lakes. At the highest elevations, the tundra has rocky plateaus. Lower terrains include finer materials and are often patterned. Such patterns usually consist of polygons (many-sided figures) where the ground is level and stripes where it is sloped. The polygons are separated by borders of ice wedges, boulders, or other materials.
Tundra soils generally contain partially decayed plant material called peat. Peat accumulates because low temperatures inhibit the decay of dead vegetation.
Tundra plant life features such flowering herbaceous (nonwoody) plants as grasses and sedges, as well as dwarf shrubs and mosses. The tundra also contains plantlike organisms called lichens. Toward the southern borders of the tundra, lowland regions have a continuous cover of vegetation. Plants become more sparse at higher elevations and in northern areas.
The tundra supports a remarkable variety of animals. Caribou, reindeer, and musk oxen eat tundra plants. So do hares, lemmings, and mice. Foxes, owls, and wolves feed primarily on the smaller animals. Wolves also may eat the young or carrion (dead and decaying flesh) of the larger grazing mammals. Numerous birds, including the Canada goose, migrate to tundra regions in summer.
People have traveled through and lived in the tundra for thousands of years. Many permanent tundra residents traditionally survived by hunting and by fishing in nearby Arctic waters. Inuit, the most widespread of these peoples, live in Alaska, Greenland, northern Canada, and the northeastern tip of Russia. Today, however, few Arctic peoples follow their traditional ways of life.
Tundra regions possess large deposits of coal, natural gas, oil, iron ore, lead, and zinc. Since the late 1800’s, people have increasingly come to the tundra to mine these resources. Increased human activity threatens the tundra’s natural environment, as well as the remaining traditional Arctic cultures.
See also Podzol.
