Tundra

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 typeET

In physical geography, tundra (n-/) 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 Sami 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.

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

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.

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 15–25 cm (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

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 with 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] 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.[9] Methane is produced when vegetation decays in lakes and wetlands.[10]

The amount of greenhouse gases which will be released under projected scenarios for global warming have not been reliably quantified by scientific studies, although a few studies were reported to be underway in 2011. It is uncertain whether the impact of increased greenhouse gases from this source will be minimal or massive.[10]

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.[10] Such events may both result from and contribute to global warming.[11]

Other Languages
Afrikaans: Toendra
العربية: تندرا
aragonés: Tundra
asturianu: Tundra
azərbaycanca: Tundra
беларуская: Тундра
беларуская (тарашкевіца)‎: Тундра
български: Тундра
bosanski: Tundra
català: Tundra
Чӑвашла: Тундра
Cebuano: Tundra
čeština: Tundra
dansk: Tundra
Deutsch: Tundra
eesti: Tundra
Ελληνικά: Τούνδρα
español: Tundra
Esperanto: Tundro
euskara: Tundra
فارسی: توندرا
français: Toundra
Frysk: Tûndra
Gaeilge: Tundra
galego: Tundra
한국어: 툰드라
հայերեն: Տունդրա
हिन्दी: टुण्ड्रा
hrvatski: Tundra
Ido: Tundro
Bahasa Indonesia: Tundra
interlingua: Tundra
ᐃᓄᒃᑎᑐᑦ/inuktitut: ᓇᐹᖅᑐᖃᕈᓐᓇᙱᑦᑐᖅ
Iñupiak: Nunivaq
íslenska: Freðmýri
italiano: Tundra
עברית: טונדרה
ქართული: ტუნდრა
қазақша: Тундра
Kiswahili: Tundra
Kreyòl ayisyen: Toundra
Кыргызча: Тундра
Latina: Tundra
latviešu: Tundra
lietuvių: Tundra
Ligure: Tundra
Limburgs: Toendra
lingála: Tundula
magyar: Tundra
македонски: Тундра
മലയാളം: തുന്ദ്ര
Bahasa Melayu: Tundra
Nederlands: Toendra
日本語: ツンドラ
Nordfriisk: Tundra
norsk: Tundra
norsk nynorsk: Tundra
occitan: Tondra
олык марий: Тундро
oʻzbekcha/ўзбекча: Tundra
پنجابی: ٹنڈرا
polski: Tundra
português: Tundra
română: Tundră
русский: Тундра
саха тыла: Туундара
Scots: Tundra
shqip: Tundra
Simple English: Tundra
slovenčina: Tundra
slovenščina: Tundra
کوردی: تەندرا
српски / srpski: Тундра
srpskohrvatski / српскохрватски: Tundra
Basa Sunda: Tundra
suomi: Tundra
svenska: Tundra
Tagalog: Tundra
Türkçe: Tundra
українська: Тундра
Tiếng Việt: Đài nguyên
West-Vlams: Toendra
粵語: 凍原
žemaitėška: Tondra
中文: 凍原