Why is the Tundra Biome notably the Coldest Biome in the World
Tundra biome is the coldest of all the biomes. Tundra comes from the Finnish word tunturi, meaning treeless plain.
It is noted for its frost-molded landscapes, extremely low temperatures, little precipitation, poor nutrients, and short growing seasons. Dead organic material functions as a nutrient pool.
In physical geography, tundra (/ˈtʌndrə, ˈtʊn-/) is a type of biome where the tree growth is hindered by low temperatures and short growing seasons.
Tundra vegetation is composed of dwarf shrubs, sedges and grasses, mosses, and lichens.
Scattered trees grow in some tundra regions. The ecotone (or ecological boundary region) between the tundra and the forest is known as the tree line or timberline. The tundra soil is rich in nitrogen and phosphorus.
There are three regions and associated types of tundra: Arctic tundra,alpine tundra,and Antarctic tundra.
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 upper surface, 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. The fauna in the arctic is also diverse:
- Herbivorous mammals: lemmings, voles, caribou, arctic hares and squirrels
- Carnivorous mammals: arctic foxes, wolves, and polar bears
- Migratory birds: ravens, snow buntings, falcons, loons, 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
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.
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
Antarctic tundra occurs on Antarctica and on several Antarctic and subantarctic 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.
There is some ambiguity on whether Magellanic moorland, on the west coast of Patagonia, should be considered tundra or not.
Phytogeographer Edmundo Pisano called it tundra (Spanish: tundra Magallánica) since he considered the low temperatures key to restrict plant growth.
The flora and fauna of Antarctica and the Antarctic Islands (south of 60° south latitude) are protected by the Antarctic Treaty.
Plants and animals in tundras
Mountain goats, sheep, marmots, and birds live in mountain—or alpine—tundra and feed on the low-lying plants and insects.
Hardy flora like cushion plants survive in the mountain zones by growing in rock depressions, where it is warmer and they are sheltered from the wind.
The Arctic tundra, where the average temperature is -30 to 20 degrees Fahrenheit (-34 to -6 degrees Celsius), supports a variety of animal species, including Arctic foxes, polar bears, gray wolves, caribou, snow geese, and musk oxen.
The summer growing season is just 50 to 60 days, when the sun shines up to 24 hours a day.
The relatively few species of plants and animals that live in the harsh conditions of the tundra are essentially clinging to life.
They are highly vulnerable to environmental stresses like reduced snow cover and warmer temperatures brought on by global warming.