Tundra

Tundra is the coldest of all the biomes. Tundra comes from the Finnish word tunturia, meaning treeless plain.
Characteristics of Tundra

1. Extremely cold climate
2. Low biotic diversity
3. Simple vegetation structure
4. Limitation of drainage
5. Short season of growth and reproduction
6. Energy and nutrients in the form of dead organic material
7. Large population oscillations
8. two major nutrients are nitrogen (biological fixation) and phosphorus (precipitation)

Tundra is separated into two types: arctic tundra and alpine tundra.

Arctic

• Arctic tundra is located in the northern hemisphere, encircling the north pole and extending south to the coniferous forests of the taiga.
• The arctic is known for its cold,desert-like conditions. The growing season ranges from 50 to 60 days. The average winter temperature is -34° C (-30° F), but the average summer temperature is 3-12° C
  (37-54° F) which enables this biome to sustain life. Rainfall may vary in different regions of the arctic. Yearly precipitation, including melting snow, is 15 to 25 cm (6 to 10 inches).
• Soil is formed slowly. A layer of permanently frozen subsoil called permafrost exists, consisting mostly of gravel and finer material.
• When water saturates the uppersurface, bogs and ponds may form, providing moisture for plants. There are no deep root systems in the vegetation of the arctic tundra, however, there are still a wide variety of plants that are able to resist the cold climate. There are about 1,700 kinds of plants in the arctic and subarctic, and these include: low shrubs, sedges, reindeer mosses, liverworts, and grasses, 400 varieties of flowers, crustose, and foliose lichen All of the plants are adapted to sweeping winds and disturbances of the soil. Plants are short and group together to resist the cold temperatures and are protected by the snow during the winter. They can carry out photosynthesis at low temperatures and low light intensities. The growing seasons are short and most plants reproduce by budding and division rather than sexually by flowering.
• Animals are adapted to handle long, cold winters and to breed and raise young quickly in the summer. Animals such as mammals and birds also have additional insulation from fat. Many animals hibernate during the winter because food is not abundant. Another alternative is to migrate south in the winter, like birds do. Reptiles and amphibians are few or absent because of the extremely cold temperatures. Because of constant immigration and emigration, the population continually oscillates.
  Herbivorous mammals: lemmings, voles, caribou, arctic hares and squirrels
  Carnivorous mammals: arctic foxes, wolves, and polar bears
  Migratory birds: ravens, snow buntings, falcons, loons, ravens, sandpipers, terns, snow birds, and various species of gulls
  Insects: mosquitoes, flies, moths, grasshoppers, blackflies and arctic bumble bees
  Fish: cod, flatfish, salmon, and trout

Alpine

• Alpine tundra is located on mountains throughout the world at high altitude where trees cannot grow.
• The growing season is approximately 180 days.
• The nighttime temperature is usually below freezing.
• Unlike the arctic tundra, the soil in the alpine is well drained. The plants are very similar to those of the arctic ones and include: tussock grasses, dwarf trees, small-leafed shrubs, and heaths
• Animals living in the alpine tundra are also well adapted:
  Mammals: pikas, marmots, mountain goats, sheep, elk
  Birds: grouselike birds
  Insects: springtails, beetles, grasshoppers, butterflies

edited from information on UCMP The World's Biomes website