The Arctic Tundra Biome
The arctic tundra, located between the North pole and the forests of the taiga, is a treeless region characterized by frigid temperatures, poor soil, limited precipitation and a short growing season. A wide variety of plants and animals are adapted to live there, but climate change, hunting, mining, and other factors have threatened some of these tundra species that are rapidly becoming endangered.
The range of the Peary caribou (Rangifer tarandus pearyi) is limited to the Queen Elizabeth Islands of northern Canada and the northwest coast of Greenland. Rising average temperatures cause increased precipitation, burying under a thick layer of show or ice the mosses and lichens that are an important part of the caribou's winter diet. The amount of food available in the summer is also decreasing. Reduced accessibility to food diminishes survival rates and results in fewer calves being born. Human activities including mining, exploring for gas or oil, road building and hunting further threaten caribou populations in the Canadian arctic.
While the arctic fox (Alopex lagopus) is not endangered world-wide, two subspecies are critically endangered in certain areas. Arctic fox populations in Fennoscandia (Finland, Norway, Sweden and the Kola Peninsula) were drastically reduced by fur hunters, and foxes on Russia's Mednyi Island were nearly wiped out by an infestation of mange caused by parasitic ticks spread by dogs. Although the foxes are now protected in these regions, dwindling populations have not recovered. The low population density makes it difficult for foxes to find a mate, which limits breeding. The small numbers of foxes are also sensitive to fluctuations in the availability of prey and outbreaks of disease. Further threats to the arctic fox include diminishing arctic ice, which allows red foxes from adjoining habitats to encroach on the territory of the arctic foxes and compete for food.
Polar bears (Ursus maritimus) currently have an IUCN status of vulnerable, meaning the risk of extinction is high. They are considered threatened under the U.S. Endangered Species Act. The range of polar bears extends throughout the circumpolar region, including Alaska, Canada, Greenland, Norway and Russia. Because polar bears spend the majority of their time on the sea ice, they are actually considered to be marine mammals. Their main food source is the ringed seal, which they hunt on the ice or at breathing holes. It is difficult for polar bears to catch seals in the open water, and when the bears are driven to land by receding ice, food is scarce. Overhunting caused a significant decrease in polar bear populations in the 1960s, but this threat has lessened since hunting restrictions have been established. Currently, the primary threat to the survival of polar bears is the loss of sea ice due to climate change. Increasing temperatures have caused sea ice to disappear at record rates, and polar bear populations in many areas are declining.
"The Tundra Biome." University of California Museum of Paleontology, www.ucmp.berkeley.edu
"Caribou in Canada." Canadian Geographic Magazine, www.canadiangeographic.ca
SEFALO The Swedish-FInnish-Norwegian Arctic Fox Project www.zoologi.su.se/research/alopex
Polar Bears International www.polarbearsinternational.org