The word “tundra” comes from a Lappish word meaning “treeless land” or “barren land”. Most of the tundra biome’s 3.3 million square miles is located in the Arctic region of the world, above the northernmost limit for tree growth. Even though the tundra landscape is defined by rhythmic freezing and thawing, it still supports an extensive array of wildlife and vegetation.
The arctic tundra comprises the majority of the tundra landscape in the world, with 2 million square miles in North America and 1.3 million square miles in Eurasia. The North American tundra begins with coastal Greenland, goes west through northern Canada and extends all the way through northern Alaska. Tundra in Eurasia covers Siberia, parts of Russia, northern Scandinavia and Iceland. A second type of tundra, called alpine tundra, exists on high-altitude mountaintops throughout the world. Mt. Rainier National Park in Washington is one example of alpine tundra.
The tundra landscape is broken up into three distinct zones. The climate in each zone greatly impacts the landscape, vegetation, and animal life that exists there. The permanent permafrost zone is centered at the North Pole and spreads outward to the arctic circle, northern Greenland, and the northernmost part of North America. This landscape never thaws. The next zone—semi-permanent permafrost—accounts for more than a third of the tundra biome. During the region’s short summer, the top layer of soil thaws for long enough to support insect, animal and vegetal life. Further south lies the sporadic permafrost zone, which is about as large as the semi-permanent region. There, land freezes less often and the thaw goes deeper into the soil, resulting in a wider variety of life. This zone also has poor soil drainage due to its permafrost layer, and supports very few trees.
“Periglacial landforms are those features that develop under the action of hard frosts, often in permafrost conditions,” states the Smithsonian Institute’s book “Earth.” The arctic tundra is filled with periglacial landforms, including pingos, ice wedges, ice lenses and block fields. Pingos are small hills resulting from ice—trapped between layers of soil and rock—which heaves and bulges the land up into a mound. Ice wedges are similarly made, but rather than forming mounds, the wedges are unusually-shaped ice masses. Ice lenses occur when ice trapped in soil sinks, developing a convex exterior. Block fields are the result of large sedimentary rock walls breaking down into fields of rubble after excessive freezing and thawing.
Vegetation found in arctic and alpine tundra include moss, lichen, several varieties of grasses and flowers, and low-lying shrubs. Because of arctic tundra’s layer of poorly draining permafrost, plant growth is limited to the active layer of topsoil, where standing water and bogs also easily form with precipitation. Both arctic and alpine tundra are characterized by their inability to support trees, but the soil of alpine tundra is more well-drained because it lacks the permafrost layer. The annual freezing and thawing of the arctic tundra results in geometrically patterned plant growth, most easily seen from the air.
The animals, birds and insects found in the tundra landscape are well-adapted to it. Most animals hibernate in the winter and mate and raise their offspring during the short summer. The great majority of tundra birds live there only in the summer, migrating south for the winter. Some animals, like squirrels, caribou, arctic hares, lemmings, musk ox and voles eat only plants, while other animals, such as polar bears, arctic foxes and wolves, are carnivorous. Cod, salmon and trout make their way into waters of the tundra. Bird species include ravens, loons, penguins, falcons and various gulls. With ample standing water in the summertime, even mosquitoes have adapted to the tundra.