The tundra comprises of arctic plains encompassing most of the earth s terrain north of the coniferous forest belt. It is dominated by sedge, heath, moss, willow, and lichen. These areas are called the arctic tundra. Similar plains, which are called the alpine tundra, occur above the timberline in the high mountains of the world. The continent of Antarctica also has a few areas of tundra. The tundra climate is characterized by harsh winters, low average temperatures, little precipitation, and a short summer season. The arctic tundra is influenced by permafrost, a layer of permanently frozen subsoil in the ground.
The number of plant species on the tundra is few, and their growth is low, with most of the biomass concentrated in the roots. Typical arctic vegetation comprises cotton grass, sedge, and dwarf heath, together with associated mosses and lichens. These plant communities are adapted to sweeping winds and to soil disturbance from frost heaves. They carry on photosynthesis at low temperatures, low light intensities, and long periods of daylight. An alpine plant community consists of mat-forming and cushion-forming plants, rare in the Arctic.
Arctic wildlife is circumpolar; the same or closely related species are found around the world. The variety of animal life is also limited in the challenging environment. Musk-ox, caribou, and reindeer are the dominant large grazers, feeding on grass, sedge, lichen, and willow. Arctic hares and lemming feed on grass and sedge. Predators include the wolf, arctic fox, and snowy owl. Polar bears, and sometimes brown bears are seen. Many birds make home in the tundra shrubbery during the summer, migrating to milder climates before the winter sets in. Invertbrate life is scarce, but insects such as black flies and mosquitoes are abundant. Alpine animal life includes the mountain goat, big horned sheep, pika, marmot, and the ptarmigan. Flies are scarce, but butterflies, beetles, and grasshoppers are abundant.