The Tundra represents the most northerly biome in North America and Eurasia. It covers one fifth of the earth's surface and has a very uniform appearance.
Vegetation in this area is dominated by various glasslike plants, heathers, and lichens. Very few trees are present, and those which do survive, are restricted to areas of streams and lakes (Raven and Johnson, 1992).
The climate is cold and dry, with the annual precipitation being less than 25 cm/yr. As a result, permafrost usually underlies the area, within a meter of the surface.