Tundra

In physical geography, tundra is an area where tree growth is hindered by low temperatures and short growing seasons. The term tundra comes from the Finnish word tunturia, which means treeless plain.

There are three types of tundra: arctic tundra, antarctic tundra, and alpine tundra. In all of these types, the dominant vegetation is grasses, mosses, and lichens. Trees do not grow in the tundra. The ecotone (or ecological boundary region) between the tundra and the forest is known as the tree-line or timberline.

See also:

• Fellfields
• Desert - tree growth hindered by low rainfall
• Heath, Pasture - tree growth hindered by human activity, not climate
• Alpine climate

Arctic tundra

Arctic tundra occurs in the far Northern hemisphere, north of the taiga belt. Arctic tundra includes vast areas of northern Russia and Canada. The subsoil of arctic tundra is permafrost, which contains permanently frozen water. The arctic tundra is home to several peoples who are mostly nomadic reindeer herders, among them are the Sami.

Notable animals in the arctic tundra include:

• Caribou or Reindeer
• Musk ox
• Polar bear
• Lemmings

Due to the harsh climate of the arctic tundra, regions of this kind have seen little exploitation even though they are sometimes rich in natural resources such as oil and uranium. In recent time this has begun to change, and in Alaska, Russia and some other parts of the world the tundra is being ever more subjected to human interference.

Antarctic tundra

Antarctic tundra occurs on Antarctica and on several antarctic and subantarctic islands, including South Georgia and the South Sandwich Islands and the Kerguelen Islands. Antarctica is mostly too cold and dry to support vegetation, and most of the continent is covered by ice fields. However, some portions of the continent, particularly the Antarctic Peninsula, have areas of rocky soil that support tundra. Its flora presently consists of around 250 lichens, 100 mosses, 25-30 liverworts, around 700 terrestrial and aquatic algal species, which live on the areas of exposed rock and soil around the shore of the continent. Antarctica's two flowering plant species, the Antarctic hair grass (Deschampsia antarctica) and Antarctic pearlwort (Colobanthus quitensis), are found on the northern and western parts of the Antarctic Peninsula.

In contrast with the arctic tundra, the antarctic tundra lacks a large mammal fauna, mostly due to its physical isolation from the other continents. Sea mammals and sea birds, including seals, penguins, inhabit areas near the shore, and some small mammals, like rabbits and cats, have been introduced by humans to some of the subantarctic islands.

The flora and fauna of Antarctica and the Antarctic Islands (south of 60º south latitude) are protected by the Antarctic Treaty.

Alpine tundra

Typical alpine tundra

Alpine tundra occurs at high enough altitude at any latitude on Earth. Alpine tundra also lacks trees, but does not usually have permafrost, and alpine soils are generally better drained than permafrost soils. Alpine tundra transitions to subalpine forests or Montane grasslands and shrublands below the tree-line; stunted forests occurring at the forest-tundra ecotone are known as Krummholz.

Notable animals in the alpine tundra include:

• Kea parrot
• Marmot
• Mountain goat
• Pika

Tundra ecoregions

External link

• Tundra biome information from the University of California (http://www.ucmp.berkeley.edu/glossary/gloss5/biome/tundra.html)
• Arctic tundra biome information from the WWF (http://www.panda.org/about_wwf/where_we_work/ecoregions/global200/pages/habitat/habitat11.htm)
• Alpine tundra information from the WWF (http://www.panda.org/about_wwf/where_we_work/ecoregions/global200/pages/habitat/habitat10.htm)

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