Tundra

The word comes from the Russian "ту́ндра" (tundra). The first use of tundra in English was in 1824, spelled "toundra", possibly indicating borrowing from French. The origin of the Russian word is uncertain: it may be a borrowing of the word "тундар" (tundar) the Sámi language family word for "fell", "elevated wasteland" or "marshy plain", from the 16th century. Some sources attribute the origin to Finnish The soil there is frozen from down, making it impossible for trees to grow there. 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. en in the Kakagrak Hills, Alaska The biodiversity of tundras 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. There are also a few fish species. There are few species with large populations. Notable plants in the Arctic tundra include blueberry (Vaccinium uliginosum), crowberry (Empetrum nigrum), reindeer lichen (Cladonia rangiferina), lingonberry (Vaccinium vitis-idaea), and Labrador tea (Rhododendron groenlandicum). and even polar bears near the ocean. The 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 climate change A severe threat to tundra is climate change, which causes permafrost to thaw. The thawing of the permafrost in a given area on human time scales (decades or centuries) could radically change which species can survive there. It also represents a significant risk to infrastructure built on top of permafrost, such as roads and pipelines. In locations where dead vegetation and peat have accumulated, there is a risk of wildfire, such as the of tundra which burned in 2007 on the north slope of the Brooks Range in Alaska. Such events may both result from and contribute to global warming. Carbon emissions from permafrost thaw contribute to the same warming which facilitates the thaw, making it a positive climate change feedback. The warming also intensifies the Arctic water cycle, and the increased amounts of warmer rain are another factor which increases permafrost thaw depths. The IPCC Sixth Assessment Report estimates that carbon dioxide and methane released from permafrost could amount to the equivalent of carbon dioxide per of warming. For comparison, by 2019, annual anthropogenic emission of carbon dioxide alone stood around . == Antarctic ==

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 or cold deserts. 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 species of 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. 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 seabirds, 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, an ecoregion that includes the Bounty Islands, Auckland Islands, Antipodes Islands, the Campbell Islands, and Macquarie Island. Species endemic to this ecoregion include the windswept helmet-orchid (Corybas dienemus) and the grooved helmet-orchid (Corybas sulcatus), the only subantarctic orchids; the royal penguin; and the Antipodean albatross. Edmundo Pisano, a Chilean Phytogeographer, called it tundra () since he considered the low temperatures key to restrict plant growth. The flora and fauna of Antarctica and the Antarctic Islands (south of 60° south latitude) are protected by the Antarctic Treaty System. == Alpine ==

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 generally better drained than arctic soils. Alpine tundra transitions to subalpine forests below the tree line; stunted forests occurring within the forest-tundra ecotone are known as Krummholz. Alpine tundra can be affected by woody plant encroachment. 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. 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 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 (), but no month with an average temperature in excess of . 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, mountain areas of Scandinavia, European Russia, and Western Siberia (cold winters with months of freezing). 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. == See also ==