Tundra

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Tundra
Greenland scoresby-sydkapp2 hg.jpg
Tundra in Greenland
800px-Map-Tundra.png
Map showing Arctic tundra
Geography
Area11,563,300 km2 (4,464,600 sq mi)
Climate type ET

In physical geography, tundra ( /ˈtʌndrə,ˈtʊn-/ ) is a type of biome where the tree growth is hindered by low temperatures and short growing seasons. The term tundra comes through Russian тундра (tûndra) from the Kildin Sámi word тӯндар (tūndâr) meaning "uplands", "treeless mountain tract". [1] 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.

Contents

There are three regions and associated types of tundra: Arctic tundra, [2] alpine tundra, [2] and Antarctic tundra. [3]

Arctic

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. [2] 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).

Tundra in Siberia Tundra in Siberia.jpg
Tundra in Siberia

Arctic tundra contains areas of stark landscape and is frozen for much of the year. The soil there is frozen from 25 to 90 cm (10 to 35 in) down, making it impossible for trees to grow. Instead, bare and sometimes rocky land can only support certain kinds of Arctic vegetation, 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 seasonally-frozen soil 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 tundras are sometimes the subject of habitat conservation programs. In Canada and Russia, many of these areas are protected through a national Biodiversity Action Plan.

Vuntut National Park in Canada Vontut National Park.jpg
Vuntut National Park in Canada

Tundra tends to be windy, with winds often blowing upwards of 50–100 km/h (30–60 mph). However, in terms of precipitation, it is desert-like, with only about 150–250 mm (6–10 in) falling per year (the summer is typically the season of maximum precipitation). Although precipitation is light, evaporation is also relatively minimal. During the summer, the permafrost thaws just enough to let plants grow and reproduce, but because the ground below this is frozen, the water cannot sink any lower, and so the water forms the lakes and marshes found during the summer months. There is a natural pattern of accumulation of fuel and wildfire which varies depending on the nature of vegetation and terrain. Research in Alaska has shown fire-event return intervals (FRIs) that typically vary from 150 to 200 years, with dryer lowland areas burning more frequently than wetter highland areas. [4]

A group of muskoxen in Alaska Muskox and Geese.jpg
A group of muskoxen in Alaska

The biodiversity of tundra is low: 1,700 species of vascular plants and only 48 species of land mammals can be found, although millions of birds migrate there each year for the marshes. [5] There are also a few fish species. There are few species with large populations. Notable animals in the Arctic tundra include reindeer (caribou), musk ox, Arctic hare, Arctic fox, snowy owl, lemmings, and even polar bears near the ocean. [6] Tundra is largely devoid of poikilotherms such as frogs or lizards.

Due to the harsh climate of Arctic tundra, regions of this kind have seen little human activity, even though they are sometimes rich in natural resources such as petroleum, natural gas and uranium. In recent times this has begun to change in Alaska, Russia, and some other parts of the world: for example, the Yamalo-Nenets Autonomous Okrug produces 90% of Russia's natural gas.

Relationship to global warming

A severe threat to tundra is global warming, which causes permafrost to melt. The melting of the permafrost in a given area on human time scales (decades or centuries) could radically change which species can survive there. [7]

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, [8] [9] 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. [10] Methane is produced when vegetation decays in lakes and wetlands. [11]

The amount of greenhouse gases which will be released under projected scenarios for global warming have not been reliably quantified by scientific studies. [11] [9] [12]

In locations where dead vegetation and peat has accumulated, there is a risk of wildfire, such as the 1,039 km2 (401 sq mi) of tundra which burned in 2007 on the north slope of the Brooks Range in Alaska. [11] Such events may both result from and contribute to global warming. [13]

Antarctic

Tundra on the Kerguelen Islands. 11 Le Mont Werth (908m) devant le Ross.jpg
Tundra on the Kerguelen Islands.

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. [14] 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. [15] Species endemic to this ecoregion include Nematoceras dienemum and Nematoceras sulcatum , the only subantarctic orchids; the royal penguin; and the Antipodean albatross. [15]

There is some ambiguity on whether Magellanic moorland, on the west coast of Patagonia, should be considered tundra or not. [16] Phytogeographer Edmundo Pisano called it tundra (Spanish : tundra Magallánica) since he considered the low temperatures key to restrict plant growth. [16]

The flora and fauna of Antarctica and the Antarctic Islands (south of 60° south latitude) are protected by the Antarctic Treaty. [17]

Alpine

Alpine tundra in the North Cascades of Washington, United States Sahale Peak.jpg
Alpine tundra in the North Cascades of Washington, United States

Alpine tundra does not contain trees because the climate and soils at high altitude block tree growth. The cold climate of the alpine tundra is caused by the low air temperatures, and is similar to polar climate. 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 plants that grow close to the ground, including perennial grasses, sedges, forbs, cushion plants, mosses, and lichens. [18] The flora is adapted to the harsh conditions of the alpine environment, which include low temperatures, dryness, ultraviolet radiation, and a short growing season.

Climatic classification

Tundra region with fjords, glaciers and mountains. Kongsfjorden, Spitsbergen. Kongsfjorden from Blomstrandhalvoja.jpg
Tundra region with fjords, glaciers and mountains. Kongsfjorden, Spitsbergen.

Tundra climates ordinarily fit the Köppen climate classification ET, signifying a local climate in which at least one month has an average temperature high enough to melt snow (0 °C (32 °F)), but no month with an average temperature in excess of 10 °C (50 °F). The cold limit generally meets the EF climates of permanent ice and snows; the warm-summer limit generally corresponds with the poleward or altitudinal limit of trees, where they grade into the subarctic climates designated Dfd, Dwd and Dsd (extreme winters as in parts of Siberia), Dfc typical in Alaska, Canada, parts of Scandinavia, European Russia, and Western Siberia (cold winters with months of freezing), or even Cfc (no month colder than −3 °C (27 °F) as in parts of Iceland and southernmost South America). Tundra climates as a rule are hostile to woody vegetation even where the winters are comparatively mild by polar standards, as in Iceland.

Nenets people are nomadic reindeer herders Stoibishche nentsev.jpg
Nenets people are nomadic reindeer herders

Despite the potential diversity of climates in the ET category involving precipitation, extreme temperatures, and relative wet and dry seasons, this category is rarely subdivided. Rainfall and snowfall are generally slight due to the low vapor pressure of water in the chilly atmosphere, but as a rule potential evapotranspiration is extremely low, allowing soggy terrain of swamps and bogs even in places that get precipitation typical of deserts of lower and middle latitudes. The amount of native tundra biomass depends more on the local temperature than the amount of precipitation.

Places featuring a Tundra Climate[ citation needed ]

See also

Related Research Articles

Taiga The worlds largest land biome, characterized by coniferous forests

Taiga, generally referred to in North America as boreal forest or snow forest, is a biome characterized by coniferous forests consisting mostly of pines, spruces, and larches.

Polar climate

The polar climate regions are characterized by a lack of warm summers. Every month in a polar climate has an average temperature of less than 10 °C (50 °F). Regions with polar climate cover more than 20% of the Earth's area. Most of these regions are far from the equator, and in this case, winter days are extremely short and summer days are extremely long. A polar climate consists of cool summers and very cold winters, which results in treeless tundra, glaciers, or a permanent or semi-permanent layer of ice.

Geography of Norway

Norway is a country located in Northern Europe on the northern and western parts of the Scandinavian Peninsula. The majority of the country borders water, including the Skagerrak inlet to the south, the North Sea to the southwest, the North Atlantic Ocean to the west, and the Barents Sea to the north. It has a land border with Sweden to the east and a shorter border with Finland and an even shorter border with Russia to the northeast.

Permafrost soil frozen for a duration of at least two years

In geology, permafrost is ground, including rock or (cryotic) soil, with a temperature that remains at or below the freezing point of water 0 °C (32 °F) for two or more years. Most permafrost is located in high latitudes, but at lower latitudes alpine permafrost occurs at higher elevations. Ground ice is not always present, as may be in the case of non-porous bedrock, but it frequently occurs, and it may be in amounts exceeding the potential hydraulic saturation of the ground material. Permafrost accounts for 0.022% of total water on Earth, and the permafrost region covers 24% of exposed land in the Northern Hemisphere. It also occurs subsea on the continental shelves of the continents surrounding the Arctic Ocean, portions of which were exposed during the last glacial period.

Alpine tundra biome

Alpine tundra is a type of natural region or biome that does not contain trees because it is at high elevation. As the latitude of a location approaches the poles, the threshold elevation for alpine tundra gets lower until it reaches sea level, and alpine tundra merges with polar tundra.

Tree line edge of the habitat at which trees are capable of growing

The tree line is the edge of the habitat at which trees are capable of growing. It is found at high elevations and high latitudes. Beyond the tree line, trees cannot tolerate the environmental conditions. The tree line is sometimes distinguished from a lower timberline or forest line, which is the line below which trees form a forest with a closed canopy.

Antipodes Subantarctic Islands tundra

The Antipodes Subantarctic Islands tundra ecoregion, within the Tundra Biome, includes five remote island groups in the Southern Ocean south of New Zealand: the Bounty Islands, Auckland Islands, Antipodes Islands and Campbell Island groups of New Zealand, and Macquarie Island of Australia.

Polar desert regions of the Earth under an ice cap with very low rainfall and no vegetation; type EF under the Köppen classification

Ice deserts are the regions of the Earth that fall under an ice cap climate. Despite rainfall totals low enough to normally classify as a desert, polar deserts are distinguished from true deserts by low annual temperatures and evapotranspiration. Most polar deserts are covered in ice sheets, ice fields, or ice caps. Ice-free areas have no vegetation as trees cannot grow in ice.

Polar ecology is the relationship between plants and animals in a polar environment. Polar environments are in the Arctic and Antarctic regions. Arctic regions are in the Northern Hemisphere, and it contains land and the islands that surrounds it. Antarctica is in the Southern Hemisphere and it also contains the land mass, surrounding islands and the ocean. Polar regions also contain the subantarctic and subarctic zone which separate the polar regions from the temperate regions. Antarctica and the Arctic lie in the polar circles. The polar circles are not visible on the earth but it is shown on maps to be the areas that receives less sunlight due to less radiation. These areas either receive sunlight or shade 24 hours a day because of the earth's tilt. Plants and animals in the polar regions are able to withstand living in harsh weather conditions but are facing environmental threats that limit their survival.

Holdridge life zones global bioclimatic scheme for the classification of land areas

The Holdridge life zones system is a global bioclimatic scheme for the classification of land areas. It was first published by Leslie Holdridge in 1947, and updated in 1967. It is a relatively simple system based on few empirical data, giving objective mapping criteria. A basic assumption of the system is that both soil and climax vegetation can be mapped once the climate is known.

Polar seas A collective term for the Arctic Ocean and the southern part of the Southern Ocean

Polar seas is a collective term for the Arctic Ocean and the southern part of the Southern Ocean. In the coldest years, sea ice can cover around 13 percent of the Earth's total surface at its maximum, but out of phase in the two hemispheres. The polar seas contain a huge biome with many organisms.

Arctic coastal tundra

The Arctic coastal tundra is an ecoregion of the far north of North America, an important breeding ground for a great deal of wildlife.

Ice cap climate

An ice cap climate is a polar climate where no mean monthly temperature exceeds 0 °C (32 °F). The climate covers areas in or near the high latitudes to polar regions, such as Antarctica and Greenland, that have vast deserts of snow and ice. In the coldest months, most ice cap climates have mean temperatures between -30 and -55 C. Ice cap climates are normally covered by a permanent layer of ice and have no vegetation. There is limited animal life in most ice cap climates, usually found near the oceanic margins. Although ice cap climates are inhospitable to human life, there are some small research stations scattered in Antarctica and interior Greenland.

Montane ecosystems ecosystems found in mountains

Montane ecosystems refers to any ecosystem found in mountains. These ecosystems are strongly affected by climate, which gets colder as elevation increases. They are stratified according to elevation. Dense forests are common at moderate elevations. However, as the elevation increases, the climate becomes harsher, and the plant community transitions to grasslands or tundra.

Canadian Arctic tundra

The Canadian Arctic tundra is a biogeographic designation for Northern Canada's terrain generally lying north of the tree line or boreal forest, that corresponds with the Scandinavian Alpine tundra to the east and the Siberian Arctic tundra to the west inside the circumpolar tundra belt of the Northern Hemisphere.

Altai alpine meadow and tundra Ecoregion (WWF)

The Altai alpine meadow and tundra ecoregion is a terrestrial ecoregion covering the higher elevation of the Altai Mountains at the center of the "X" formed by the borders separating Russia, Kazakhstan, China, and Mongolia. The mountain peaks are the farthest north in Central Asia, separating the plains of Siberia to the north from the hot, dry deserts to the south. Altitudes above 2,400 meters display characteristics of tundra, with patches of alpine meadows and some trees immediately below the treeline. The ecoregion is in the Montane Grasslands and Shrublands biome, and the Palearctic ecozone, with a Humid Continental climate. It covers an area of 90,132 square kilometres (34,800 sq mi).

Arctic desert Ecoregion (WWF)

The Arctic desert ecoregion is a terrestrial ecoregion that covers the island groups of Svalbard, Franz Josef Land, Severny Island and Severnaya Zemlya in the Arctic Ocean, above 75 degrees north latitude. e covered with glaciers, snow, and bare rock in a harshly cold environment. The temperature does rise above freezing for short periods in the summer, so some ice melt occurs, and the area supports colonies of sea birds and mammals. It has an area of 161,356 square kilometres (62,300 sq mi).

Trans-Baikal Bald Mountain tundra Ecoregion (WWF)

The Trans-Baikal Bald Mountain tundra ecoregion covers the high-altitude peak zones above the treeline in a series of mountain ranges that stretch from the northern reaches of Lake Baikal to the western coastal ranges of the Okhotsk Sea. Floral communities are those of mountain tundra, with bare rock or permafrost under layers of moss and lichen. Because the ecoregion is aligned along a common latitude, it acts as a route for the transmission of species across Siberia. The ecoregion is in the Palearctic ecozone and the Tundra biome. It has an area of 217,559 square kilometres (84,000 sq mi).

Yamalagydanskaja tundra Ecoregion (WWF)

The Yamal-Gydan tundra ecoregion is an ecoregion that covers the Yamal Peninsula and Gydan Peninsula in northern Russia. Plants and animals are sparse, although the area is an important one for migratory birds, and for coastal sea mammals. The ecoregion is in the Palearctic ecozone, and the Tundra biome. It has an area of 412,067 square kilometres (159,100 sq mi).

References

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Further reading