Describe the characteristics of one of the six biomes.

Tundra is a treeless biome occurring in areas with cold climates and a short growing season. Alpine tundra occurs at high altitudes on mountains, while arctic tundra occurs at high latitudes. Most tundras receive very small inputs of water as precipitation, but nevertheless their soil may be moist or wet because there is little evaporation in such cold climates, and deep drainage may be prevented by frozen soil. The coldest, most northern, high-arctic tundras are very unproductive and dominated by long-lived but short-statured plants, typically less than 1.97-3.94 in (5-10 cm) tall. Low-arctic tundras are dominated by shrubs as tall as 3.28 ft (1 m), while wet sites develop relatively productive meadows of sedge, cotton-grass, and grass. In North America, arctic tundras can support small densities of mammalian herbivores such as caribou and muskox (although during migration these animals can occur in locally large densities), and even smaller numbers of their predators, such as wolves.