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. The tundra soil is rich in nitrogen and phosphorus. [2]

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, it is desert-like, with only about 150–250 mm (6–10 in) of precipitation 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

Biome Distinct biological communities that have formed in response to a shared physical climate

A biome is a community of plants and animals that have common characteristics for the environment they exist in. They can be found over a range of continents. Biomes are distinct biological communities that have formed in response to a shared physical climate. Biome is a broader term than habitat; any biome can comprise a variety of habitats.

Taiga 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

Permafrost is ground that continuously remains below 0°C (32°F) for two or more years, located on land or under the ocean. Permafrost does not have to be the first layer that is on the ground. It can be from an inch to several miles deep under the Earth's surface. Some of the most common permafrost locations are in the Northern Hemisphere. Almost a quarter of the Northern Hemisphere is underlain by permafrost, including 85% of Alaska, Greenland, Canada and Siberia. It can also be located on mountaintops in the Southern Hemisphere. Permafrost frequently occurs in ground ice, but it can also be present in non-porous bedrock. Permafrost is formed from ice holding various types of soil, sand, and rock in combination.

Alpine tundra Biome found at high altitudes

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

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 Pacific 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 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.

Arctic ecology The study of the relationships between biotic and abiotic factors in the arctic

Arctic ecology is the scientific study of the relationships between biotic and abiotic factors in the arctic, the region north of the Arctic Circle. This region is characterized by stressful conditions as a result of extreme cold, low precipitation, a limited growing season and virtually no sunlight throughout the winter. The Arctic consists of taiga and tundra biomes, which also dominate very high elevations, even in the tropics. Sensitive ecosystems exist throughout the Arctic region, which are being impacted dramatically by global warming.

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.

North American Arctic

The North American Arctic is composed of the northern portions of Alaska (USA), Northern Canada and Greenland. Major bodies of water include the Arctic Ocean, Hudson Bay, the Gulf of Alaska and North Atlantic Ocean. The North American Arctic lies above the Arctic Circle. It is part of the Arctic, which is the northernmost region on Earth. The western limit is the Seward Peninsula and the Bering Strait. The southern limit is the Arctic Circle latitude of 66° 33’N, which is the approximate limit of the midnight sun and the polar night.

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.

Hudson Plains Ecoregion

The Hudson Plains Ecoregion is a vast, flat, and waterlogged landscape. This ecoregion covers a 369,000 square kilometer area along the south shoreline of the Hudson Bay, which includes the Canadian provinces of Eastern Quebec, Northern Ontario and Western Manitoba. Because of the location of the ecoregion, winter prevails for many months of the year and rising temperatures, along with melting ice, makes fog common. The short summers provide a home for thousands of migrating birds. The region is used by humans for its mineral resources and hydroelectric power as a result of the abundance of water and emergent societal needs. Though relatively uninhabited and undisturbed, the natural resources of the Hudson Plains are still subject to anthropogenic activities. Its climatic, geographic, and evolutionary patterns categorize it as one of many ecoregions in North America.

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.

High Arctic tundra

The High Arctic tundra ecoregion covers most of Canada's northern Arctic Archipelago - from the Queen Elizabeth Islands nearest to Greenland in the northeast, and down through the center of Baffin Island. Much of the northern islands are covered in ice, and the climate is very dry with as little as 50 mm/year in places. The ecoregion has very little human habitation, and most of the non-ice terrain is moss and lichen cover. The region supports viable populations of arctic mammals such as muskox, arctic wolves, arctic foxes, arctic hares, polar bears, and caribou.

Kalaallit Nunaat high arctic tundra

The Kalaallit Nunaat high arctic tundra ecoregion covers the coastal areas of northern and eastern Greenland. Areas inland of this strip of land are either covered in ice or bare rock. About one third of the area is covered in moss and lichen with about 3% herbaceous cover and shrubs. The largest national park in the world - Northeast Greenland National Park - protects a majority of the land.

Middle Arctic tundra

The Middle Arctic tundra ecoregion covers a broad stretch of northern Canada - the southern islands of the Arctic Archipelago, plus the northern mainland of Nunavut and, across Hudson Bay to the east, a portion of northern Quebec. This is the coldest and driest ecoregion in Canada, and can be referred to as a 'polar desert'. It is an important region for breeding and migratory bird, and supports 80% of the world's muskox.

References

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Further reading