Tundra is the coldest of all the biomes. Tundra comes from the Finnish word tunturia, 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. The two major nutrients are nitrogen and phosphorus. Nitrogen is created by biological fixation, and phosphorus is created by precipitation. Tundra is separated into two types: arctic tundra and alpine tundra.
Extremely cold climate
Low biotic diversity
Simple vegetation structure
Limitation of drainage
Short season of growth and reproduction
Energy and nutrients in the form of dead organic material
Large population oscillations
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, 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
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.
Antarctica is the fifth largest of the seven continents. It is situated over the South Pole almost entirely south of latitude 66°30’ south (the Antarctic Circle). It is a very rough circular shape with the long arm of the Antarctic Peninsula stretching towards South America. There are two large indentations, the Ross and Weddell seas and their ice shelves.
Desert is defined as a region that has less than 254 mm (10 in) of annual rainfall or precipitation. Antarctica can be classified as a desert by this definition. In the interior of the continent the average annual precipitation (in equivalent of water) is only about 50 mm (about 2 in), less than the Sahara. Along the coast, this increases, but is still only about 200 mm (8 in) in equivalent of water. Heavy snowfalls occur when cyclonic storms pick up moisture from the surrounding seas and then deposit this moisture as snow along the coasts.
Antarctica is the coldest, and also the windiest continent. The lowest temperature ever recorded anywhere on earth, -89.2° C (-128.6° F) was on July 21st 1983 at the Russian Vostok Station at the "pole of inaccessibility". This is the furthest point from any coast and so is the least affected by the warming effect of the oceans.
Despite the low precipitation levels, it frequently appears that more snow is falling than really is. The ever-present winds pick up snow that has already fallen and move it around from place to place. Blizzards are therefore common and frequently result in disorienting white-out conditions where everything in front of you becomes a white blanket with no distinguishable features.
Antarctica consists of two main areas. East Antarctica (Greater Antarctica), and smaller West Antarctica (Lesser Antarctica) which also has the Antarctic Peninsula. West Antarctica is an extension of the Andes mountains stretching from South America. It is thought that if the ice sheet were removed, West Antarctica would actually be a collection of islands.
More than 99 percent of Antarctica is covered with ice, this contains about 70 percent of the world’s fresh water. The thick ice cover makes it the highest of all continents, with an average elevation of about 2300 m (about 7500 ft). The highest point on the continent is Vinson Massif (4897 m) and the lowest point yet found is the Bentley Subglacial Trench (2499 m/8200 ft below sea level) in West Antarctica. This trench is covered with more than 3000 m (more than 9840 ft) of ice and snow. Lower points may exist under the ice, but they have not yet been discovered.
Antarctica has no trees or bushes at all, vegetation is limited to about 350 species of mostly lichens, mosses, and algae. There are lush beds of such vegetation in some parts of the Antarctic Peninsula. Lichens have been discovered growing on isolated mountains within 475 km (295 mls) of the South Pole. In some places bare rocks are colonized by vibrant red, orange and yellow growths of lichens. Where rock is uncovered by ice for large parts of the summer, green lichens that grow to a few centimeters high can give the impression from a distance of a field of dark grass albeit a bit tatty). Three species of flowering plants are also found on the Antarctic Peninsula.
The largest truly Antarctic land animals therefore are invertebrates only a few of millimeters in size. These animals, mites, ticks and nematode worms tolerate the low temperatures in the winter by becoming frozen in ice under rocks and stones. They have antifreeze in their bodies and stop all motion and bodily functions while frozen, becoming active again when the ice finally warms up sufficiently to melt. These animals live largely in the Antarctic Peninsula.
The most famous inhabitant of Antarctica has to be the penguin. A flightless bird, but excellent swimmer, penguins live on pack ice and in the oceans around Antarctica. They breed on the land or ice surfaces along the coast and on islands. Best known and most typical are the Adélie and emperor penguins.