TundraTundra [Finnish, tunturi], also called "barren land," large region of the Northern Hemisphere lacking trees and possessing abundant rock outcrops. In Canada, the southern boundary extends from the Mackenzie Delta to southern Hudson Bay and NE to Labrador. Many CLIMATE variables combine to determine the position of this boundary.
The tundra environment is characterized by the general presence of PERMAFROST (except beneath some lakes and rivers); short summers with almost continuous daylight; long winters and arctic "nights"; low annual precipitation (hence the name polar desert); strong winds and winter blizzards; discontinuous vegetation; unstable, wet SOIL conditions resulting from permafrost and frost action. Tundra plants have developed many adaptations for survival. Their low stature exploits the more favourable microclimate near the ground; small, leathery, hairy leaves prevent desiccation by evaporation.
Perennial life habit, vegetative propagation, short reproductive cycle and effective seed dispersal by wind are common among tundra plants (eg, LICHENS, MOSSES, GRASSES, low shrubs). Many birds and some animals live in the tundra in summer, migrating in autumn (see ARCTIC ANIMALS).
Tundra environments present many impediments to human activities. Buildings, pipelines, roads and airports must be so constructed that they can cope with cold climate and permafrost, and proper advance planning must precede resource development and waste disposal to avoid damage to ecosystems.
The term "alpine tundra" has been used for areas above the TREELINE in mountains. Although alpine tundra resembles arctic tundra proper in some respects, the differences are both substantial and significant. See also PHYSIOGRAPHIC REGIONS.