The ground stays frozen year round, except for a thin layer at the surface. There are two major types of tundra.
Arctic tundra dominates the far North, above the Arctic Circle.
Alpine tundra is found above timberline in the continent's major mountain ranges. Bighorn sheep, marmots, mountain goats, and grizzly bears are common animals of the tundra. Few gardeners toil in the tundra. The climate is too severe and the soil too thin for cultivation. The tundra is, however, a source of specialty plants for gardeners in more temperate regions.