In the summer the ground thaws to a depth of a few centimeters and becomes wet and soggy. This freezing and thawing cycle crushes the roots of plants keeping them small and stunted. Alpine ecosystems are mountain top versions of the tundra. The taiga is characterized by a climate of long, severe winters, and a constant cover of snow and short, cool summers. The vegetation is dominated by conifers such as spruce, fir, and hemlock.
Characteristic animals are elk, moose, mule deer, black bears, and grizzly bears.
The taiga occurs in the northern reaches of North America and Eurasia. The taiga is also sometimes referred to as boreal forest or northern coniferous forest. Taiga-like vegetation occurs on the upper elevations of mountain ranges. The dominant trees in this zone avoid water loss during the winter by shedding their leaves. The temperate deciduous forests are much richer in plant and animal species than the taiga or tundra zones.