What is tundra?
The tundra is a vast region of cold, mostly treeless lands extending along the entire margin of the Arctic Ocean. Because of the low temperatures, the ground is frozen (called permafrost, for permanently frozen ground). During the short summer, only the uppermost foot (30 cm) or less actually thaw. Under these conditions only the toughest plants can grow, and the typical tundra vegetation consists of grasses and shrubs, lacking the taller trees with deeper roots that are so common further to the South. The photograph on the right shows a low ridge in the tundra in Northern Alaska, with some willows growing at the edge of a pond. In the background you can see the Brooks Range, that separates the tundra from the forests (also called taiga or boreal forests) of interior Alaska.
On the map you can see the tundra shown in blue. Almost a quarter of the area of the state of Alaska is made up of tundra.
Tundra in spring. Everything is covered with snow. The snow depth ranges from a few centimeters to as much as a meter.Tundra in early summer. As the snow melts we can see the tundra grasses and water collects in some areas.
With the ground permanently frozen, water cannot seep deeper into the ground during summer. Instead, it collects at the surface and forms numerous tundra lakes. The satellite image at the right shows part of the tundra in northern Alaska. You can see the Arctic Ocean at the top of the image and a lot of lakes (blue) covering the tundra surface.
In summer the surface of the tundra melts and turns into soggy ground. This and the many lakes make it an ideal home for more than a hundred different species of birds that come to the tundra and the Arctic coast to breed during the short summer. Some, like the tundra swan shown at right, travel thousands and thousands of miles from the southern United States or even Mexico and Central America.
