Tundra also called barren land is a 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 northeast to Labrador. Many climate variables combine to determine the position of this boundary.

Characteristics

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.

The term "alpine tundra" has been used for areas above the treeline in mountain areas. Although alpine tundra resembles Arctic tundra in some respects, the differences are significant. (See also Physiographic Regions.)

Flora and Fauna

Tundra plants tend to be perennial and have short reproductive cycles. Their seeds are effectively dispersed by wind, and some species are capable of vegetative propagation (i.e. asexual reproduction). Plants in the region include lichens, mosses, grasses and low shrubs.

Tundra plants have developed many adaptations for survival. Their low stature exploits the more favourable microclimate near the ground, while small, leathery, hairy leaves prevent moisture loss by evaporation.

Many birds and some animals live in the tundra in summer, migrating in autumn (see Arctic Animals).

Human Activity

Tundra environments present many impediments to human activities. Buildings, pipelines, roads and airports must be constructed so 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.