What Is the Tundra?
Tundra is the name given to the cold, treeless plains. It is a type of biome where the tree growth is hindered by low temperatures and short growing seasons. There are three types of tundra: Arctic tundra, alpine tundra, and Antarctic tundra. In tundra, the vegetation is composed of dwarf shrubs, sedges and grasses, mosses, and lichens. Scattered trees grow in some tundra regions. The ecological boundary region between the tundra and the forest is known as the tree line or timberline.
Arctic tundra occurs in the far Northern Hemisphere, north of the taiga belt. The ground of the tundra is perpetually frozen. This frozen ground is called permafrost. During the short summer, the top layer thaws out. Spring wild-flowers and other plants pop up from the mossy tundra. Once again, geese, ducks and plovers fly in from the south to claim their nesting places. Snowy owls and arctic foxes are two skilled hunters of the tundra. These predators look for arctic hares, as well as plump white ptarmigans (game birds) and mouse like lemmings.
Antarctic tundra occurs on Antarctica and on several Antarctic and sub-antarctic islands, including South Georgia and the South Sandwich Islands and the Kerguelen Islands. Most of Antarctica is 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 plant life. The flora presently consists of around 300–400 lichens, 100 mosses, 25 liverworts, and around 700 terrestrial and aquatic algae 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 and 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 Antipodes Subantarctic Islands tundra ecoregion includes the Bounty Islands, Auckland Islands, Antipodes Islands, the Campbell Island group, and Macquarie Island. Species endemic to this ecoregion include Nematoceras dienemum and Nematoceras sulcatum, the only Subantarctic orchids; the royal penguin; and the Antipodean albatross.
The flora and fauna of Antarctica and the Antarctic Islands (south of 60° south latitude) are protected by the Antarctic Treaty.
Alpine tundra does not contain trees because the climate and soils at high altitude block tree growth. Alpine tundra is distinguished from arctic tundra in that alpine tundra typically does not have permafrost, and alpine soils are generally better drained than arctic soils. Alpine tundra transitions to subalpine forests below the tree line; stunted forests occurring at the forest-tundra ecotone (the treeline) are known as Krummholz.
Alpine tundra occurs in mountains worldwide. The flora of the alpine tundra is characterized by dwarf shrubs close to the ground. The cold climate of the alpine tundra is caused by the low air temperatures, and is similar to polar climate.