All about Tundra Biome

Tundra

Tundra is a biome where the tree growth is hindered by low temperatures and short growing seasons. The term tundra comes through Russian тундра from the Kildin Sami word tūndâr "uplands," "treeless mountain tract." Tundra is the coldest of all the biomes. The characteristics of tundra were it is extremely cold climate, low biodiversity, 

simple vegetation structure, limitation of drainage, short season of growth and reproduction, energy and nutrients in the form of dead organic material and large population oscillation. There are three types of tundra: Arctic tundra, alpine tundra, and Antarctic tundra.

Arctic tundra

Arctic tundra occurs in the far Northern Hemisphere, north of the taiga belt. The word "tundra" usually refers only to the areas where the subsoil is permafrost, or permanently frozen soil. (It may also refer to the treeless plain in general, so that northern Sápmi would be included.) Permafrost tundra includes vast areas of northern Russia and Canada. The polar tundra is home to several peoples who are mostly nomadic reindeer herders, such as the Nganasan and Nenets in the permafrost area (and the Sami in Sápmi).

Arctic tundra contains areas of stark landscape and is frozen for much of the year. The soil there is frozen from 25–90 cm (9.8–35.4 inches) down, and it is impossible for trees to grow. Instead, bare and sometimes rocky land can only support low growing plants such as moss, heath (Ericaceae varieties such as crowberry and black bearberry), and lichen. There are two main seasons, winter and summer, in the polar tundra areas. During the winter it is very cold and dark, with the average temperature around −28 °C (−18 °F), sometimes dipping as low as −50 °C (−58 °F). However, extreme cold temperatures on the tundra do not drop as low as those experienced in taiga areas further south (for example, Russia's and Canada's lowest temperatures were recorded in locations south of the tree line). During the summer, temperatures rise somewhat, and the top layer of the permafrost melts, leaving the ground very soggy. The tundra is covered in marshes, lakes, bogs and streams during the warm months. Generally daytime temperatures during the summer rise to about 12 °C (54 °F) but can often drop to 3 °C (37 °F) or even below freezing. Arctic tundra’s are sometimes the subject of habitat conservation programs. 

Due to the harsh climate of the Arctic tundra, regions of this kind have seen little human activity, even though they are sometimes rich in natural resources such as oil and uranium. In recent times this has begun to change in Alaska, Russia, and some other parts of the world. A severe threat to the tundra’s, specifically to the permafrost, is global warming. The melting of the permafrost in a given area on human time scales (decades or centuries) could radically change which species can survive there. Another concern is that about one third of the world's soil-bound carbon is in taiga and tundra areas. When the permafrost melts, it releases carbon in the form of carbon dioxide and methane, both of which are greenhouse gases. The effect has been observed in Alaska. In the 1970s the tundra was a carbon sink, but today, it is a carbon source.

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. 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. 

 

Alpine tundra

Alpine tundra is an ecozone that does not contain trees because it has high altitude. Alpine tundra is distinguished from arctic tundra, because 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 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 pressure, and is similar to polar climate. 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: grouse like birds; Insects: springtails, beetles, grasshoppers, butterflies.

  In tundra, the vegetation is composed of dwarf shrubs, sedges and grasses, mosses, and lichens. Scattered trees grow in some tundra. 
 

Climate and Location

Tundra climate is characterized by harsh winters, low average temperatures, little snow or rainfall, and a short summer season. The arctic tundra, in particular, is influenced by permafrost, a layer of permanently frozen subsoil in the ground. The surface soil, which tends to be rocky, thaws in summer to varying depths. The combination of frozen ground and flat terrain on the tundra impedes the drainage of water. Held at the surface or soaking the upper layer of soil, the water forms ponds and bogs that provide moisture for plants, which helps to make up for the low precipitation. A graph that shows a biome's temperature and precipitation over a year's time is a climatogram.

In relatively well-drained locations, the periodic freezing and thawing of the soil forms cracks in the ground in regularly patterned polygons. Poorly drained areas produce irregular landforms such as hummocks, or knolls, frost boils, and earth stripes. Thawing of slopes in the summer may move soil down slope to produce solifluction, or "flowing soil" terraces. All of these patterns, produced on the arctic tundra, also appear on a smaller scale on the alpine tundra. Common to the alpine tundra is bare rock-covered ground, called fell-fields, supporting a growth of lichens. The numerous smaller habitats provided by these landforms give variety to the tundra landscape region between the tundra and the forest is known as the tree line or timberline.

By: Saira Usop