Arctic Tundra is characterized by:
- an extremely cold climate
- low precipitation
- surface drainage only
- small number of wildlife and plant species
- short growing season and reproduction
- limited supply of nutrients
- large variation in populations
Arctic Tundra is found in Alaska, Greenland, Canada, Europe and Siberia. No deep-rooted vegetation exists because of Permafrost (permanently frozen ground). There is as much as two months of darkness, and even in summer the sun is so close to the horizon that there is a low intensity of sunlight.
Temperatures change severely between winter (-34ºC) and summer (+12ºC). Consequently, there is a short growing season of only 50-60 days, and the vegetation has adapted to develop quickly. With a yearly rainfall of only 15-25 cm. and the presence of permafrost, bogs and ponds appear intermittently.
The permafrost also prevents water from seeping into the ground -it remains on the surface through the summer, freezes in winter and reappears the next year. The result is a large number of ponds, bogs and sloughs in an area with minimal precipitation.
Despite the severe conditions, there is a surprising amount of diversity of species in the Arctic Tundra:
Mammals – lemmings, voles, caribou, arctic hares, squirrels, arctic foxes, ermine, polar bears, porcupines, arctic shrews, weasels and wolves
Birds – Arctic loons, snowy owls, ptarmigans, snow geese, ravens, snow buntings, snow birds, sandpipers, arctic terns, tundra swans & many species of gulls
Fish – cod, flatfish, salmon, trout
Insects – arctic bumblebees, blackflies, grasshoppers, mosquitoes and moths
Amphibians – wood frogs
Few birds and mammals live year-round in the Arctic Tundra (ptarmigan, muskox, arctic hare, and arctic fox). The majority spend only the summer months here to breed and raise their offspring, and then migrate south into the boreal (fir tree) forest or further south.
Those who do live here year-round have found ways to adapt to the severe climate. For instance, the brown bear eats ravenously during the short summer in order to develop a thick layer of insulating fat. This is then slowly absorbed during its winter hibernation. The Arctic Ground Squirrels live in colonies in burrows and store food to eat during the spring and summer, lining their burrows with lichens, leaves and musk ox hair. They then roll up into a ball and sleep for seven months.
The Musk Ox has two layers of fur. Next to its body it has a short layer warmed by its own body heat. This insulates the animal from the cold. The long outer layer of fur keeps out the wind and water. Its large, hard hooves can break through the ice to obtain drinking water.
Animals and birds who live year-round in the tundra, such as the arctic fox, ptarmigan, ermine, arctic wolf, collared lemming and arctic hare go through a colour change from brown to white in winter, in order to blend into their environment.
Animals have adapted to breed and to raise their young quickly during the short summer period. Some animals, such as lemmings have a varying population, which in turn influences the survival rate of plant populations and of predators such as the snowy owl. When lemmings are in short supply, this owl will seek out food as far south as Virginia, but frequently will not survive to return to the Arctic.
Only plants with shallow root systems can survive in the Tundra, but there are an amazing variety of 1,700 kinds here, including mosses, lichens, sedges, dwarf shrubs and grasses. They are all low to the ground and have a small leaf structure in order to repel the cold temperatures and the effects of ice and snow.
Photosynthesis (a process by which green plants and other organisms use the energy of light to convert carbon dioxide and water into the simple sugar glucose with the extremely important byproduct of oxygen) can occur in conditions of low temperatures and low light, in the very short growing season (6 to 10 weeks). The large amount of snowfall helps to protect the plants during the long winter. Despite these harsh conditions, there are 400 varieties of flowers.