The tundra biome is located in a circle around the frozen arctic ice sheet that extends from the north pole to the edges of the continentental masses at the top of the world. If the earth was the head of a monk, the ice is like the tonsure and the tundra biome is the circle of thin hair around it. The tundra is circumpolar, extending across the upper edges of the Northern Hemisphere continents, across Siberia, Alaska, Canada and Northern Europe. Where the Arctic Ocean ends, the tundra begins, extending south until conditions warm up enough for boreal forest or taiga to take over.
The tundra biome is one of the most extreme ecosystems on earth. The winters are long, dark and harsh. The summers are short and freezing conditions can occur at any time. Even though the sun is shining for most of that summer, it is never high above the horizon and so it never warms the earth as much as it can further south. When clouds obscure it, the temperature quickly plummets again. Icy winds can howl across the landscape, unimpeded by mountains or tall trees.
On the tundra, the ground never totally defrosts, with a permanent layer of ice only centimeters below the surface. This aptly named permafrost determines the depth to which plant roots can reach and this in turn determines how high the plants can grow. The tundra looks like a grassland but it is not. The dominant plants are willow trees, but they can only get as tall as their roots can grow down and so they are only a few centimeters high. But in the summer, like all willows, they produce furry little catkins which are often as big as the trees themselves. These hardy plants and the other vegetation of the tundra must endure freezing conditions for most of the year. When the snow and ice finally loosens its grip, life proceeds frenetically. Plants must grow, flower and reproduce in less than three months on average, if they are to survive in this harsh environment.
The animal life must also be tough and in fact many animals leave during the winter months. Caribou migrate south to the taiga (learn taiga biome animals). Birds migrate even further, leaving winter behind if they can. They return because of the abundant insect life that flourishes in the short summers and provides food for the nesting birds. Beneath the soil and in the tiny trees are numerous insect species. Earthworms cannot survive here but there are a multitude of springtails (Insecta: Collembola), mites and nematodes to do the work of making soil and breaking down dead organic matter. Its a slow process in the cold conditions but it does occur. The invertebrates that live here have to survive being frozen for the long months of winter and then live quickly in the short spring, summer and autumn, before it all freezes over again.
Above ground, flies and mosquitoes also flourish in the snowy meltwaters that pool in depressions. These insects can make life quite uncomfortable in the summer and many eskimos actually prefer winter because of them. Great clouds of insects pester the returning caribou herds and other animals that roam the summer tundra. Musk ox herds flourish there and are one of the few animals to remain during the winter. They and the caribou can survive because the tundra is actually a kind of desert. Very little rain falls in the summer and snow falls are sparse in the winter as it is actually too cold to snow for much of the time. This means that the musk ox and caribou can dig down through the thin snow cover to the frozen vegetation to get a feed. Heavy snows can be disastrous for these animals.
Lemmings also survive all year in this environment, but they do so by hibernating in the winter. Their predators, arctic foxes survive here too as do polar bears. Polar bears hibernate in the coldest months but go out on the ice during the early and late winter months where they hunt seals and walrus. The versatile arctic foxes follow the bears and subsist on the remains of their hunts or even their feces when times are tough. In the spring, when the pack ice breaks up, they both return to shore, where polar bears can hunt other prey such as the returning caribou and the foxes can breed and feed on snowshoe hares, lemmings and voles.
The tundra is a harsh environment and yet it flourishes with life and humans have adapted to live there. Eskimos not only survived there but in their legends they said that they were given this wonderful land by a God that favored them over other men. For the most part their diet was meat but in the short summers, blueberries grow on the tundra. Eskimo ice cream was made from whale fat mixed with these delicious berries. When the pack ice retreated, whales, walruses and seals provided a bountiful harvest. There were no trees large enough to build houses, but whale bones and walrus hides could be turned into shelter and driftwood was highly prized. Eskimo hunters made walrus-hide canoes with waterproof knots for hunting whales and in winter, an eskimo hunter could stand motionless for hours in thirty below temperatures at the air hole of a seal, waiting for its return, in order to provide food for the hunter’s family. It is an environment that would kill most of us quickly but Eskimos and Siberians thrived there for thousands of years.
The tundra biome is an important part of the world’s biosphere and is one of the truly wild places left on earth. It is living proof of just how tough and persistent life is to survive and flourish in this extreme biome.
Learn more another biome: Desert biome