Polar bear on the tundra ©Getty Images

Polar bear on the tundra ©Getty Images

About 1/5 of the Earth is tundra, almost all of it in the northern hemisphere. Tundra is the coldest of all the biomes. The word comes from a Finnish (the language of Finland) word and means 'treeless plain'. The winter is long and very cold, with a short summer. 

Arctic tundra

There is arctic tundra and alpine tundra. Arctic tundra is in the northern hemisphere, around the north pole, stretching south to the taiga. The summer growing season lasts about 50 to 60 days. Winter temperatures average -34° C , but the summer temperatures average between 3-12° C, which is warm enough for plants and animals to reproduce and grow. Rainfall varies around the Arctic, but on average yearly rain and snow is 15 cm to 25 cm.

Permafrost

Alpine tundra in summer ©Getty Images

Alpine tundra in summer ©Getty Images

About a metre under the top layer of soil there is ground that is permanently frozen, called permafrost.  In the very short summers, the top level of soil thaws just long enough for plants to grow and reproduce, then become dormant (hibernate) over winter. But the permafrost layer never thaws. Because of this, tundra plants do not have deep root systems. When water soaks the upper soil surface, bogs and ponds may form and provide moisture for plants and small life forms. 

Alpine tundra

Alpine tundra is found on mountain tops all over the world, at the high altitudes where trees cannot grow.   As you climb a high mountain, you may pass through a number of biomes, such as deciduous forest, grassland, taiga and then alpine tundra. It is therefore the highest biome, and can be found anywhere on earth. The growing season is approximately 180 days. Night temperatures are below freezing. The soil in the alpine tundra is well drained so bogs and ponds do not form. The plants are similar to those in the arctic tundra and include tussock grasses, dwarf trees and small-leafed shrubs. 

Animals living in the alpine tundra include:

  • Mammals such as pikas, marmots, mountain goats, elk
  • Insects such as beetles, grasshoppers, butterflies

Plants in the tundra are low-growing, and include:

  • low shrubs, sedges, mosses, liverworts, and grasses;
  • 400 varieties of flowers;
  • lichens

Plants group together to survive the strong winds and cold temperatures. They are protected by the winter snows. They have adapted so that photosynthesis (getting food from sunlight) can occur in the low light and cold temperatures.

Arctic wolf ©Getty Images

Arctic wolf ©Getty Images

Animals found in the Arctic include:

  • Herbivorous (plant eating) mammals such as lemmings, voles, caribou, arctic hares and squirrels;
  • Carnivorous (meat eating) mammals such as arctic foxes, wolves, and polar bears;
  • Migratory birds such as ravens, falcons, loons, ravens, sandpipers, terns and snow birds who stay only for spring and summer;
  • Insects such as mosquitoes, flies, moths, grasshoppers, blackflies and arctic bumble bees.
Muskox on the tundra ©Getty Images

Muskox on the tundra ©Getty Images

Animals in the tundra have adapted to survive the long cold winters. They have an extra layer of fat to keep them warm, and in winter their fur is longer and thicker. Some are camouflaged white to blend in with the snow.   Many hibernate during the winter when food is hard to find. Others migrate to warmer places to avoid the tundra winter. This means that animal populations in the tundra fluctuate with the seasons.

Animals breed and raise their young in the short summer. There are few reptiles and amphibians in the tundra because of the cold.

Learn more about the tundra biome:

Read the kidcyber pages about other biomes: