Alpine tundra
Alpine tundra is a type of natural region or biome that does not contain trees because it is at high elevation, with an associated harsh climate. 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.
The high elevation causes an adverse climate, which is too cold and windy to support tree growth. Alpine tundra transitions to sub-alpine forests below the tree line; stunted forests occurring at the forest-tundra ecotone are known as krummholz. With increasing elevation it ends at the snow line where snow and ice persist through summer.
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
Geography
Alpine tundra occurs at high enough altitude at any
Alpine tundra occupies high-mountain summits, slopes, and ridges above timberline. Aspect plays a role as well; the
Averaging over many locations and local microclimates, the treeline rises 75 meters (245 ft) when moving 1 degree south from 70 to 50°N, and 130 meters (430 ft) per degree from 50 to 30°N. Between 30°N and 20°S, the treeline is roughly constant, between 3,500 and 4,000 meters (11,500 and 13,100 ft).[8]
Climate
In the alpine tundra, trees cannot tolerate the environmental conditions (usually cold temperatures, extreme snowpack, or associated lack of available moisture).
Quantifying the climate
There have been several attempts at quantifying what constitutes an alpine climate.
Climatologist Wladimir Köppen demonstrated a relationship between the Arctic and Antarctic tree lines and the 10 °C summer isotherm; i.e., places where the average temperature in the warmest calendar month of the year is below 10 °C cannot support forests. See Köppen climate classification for more information.
Otto Nordenskjöld theorized that winter conditions also play a role: His formula is W = 9 − 0.1 C, where W is the average temperature in the warmest month and C the average of the coldest month, both in degrees Celsius (this would mean, for example, that if a particular location had an average temperature of −20 °C (−4 °F) in its coldest month, the warmest month would need to average 11 °C (52 °F) or higher for trees to be able to survive there).
In 1947, Holdridge improved on these schemes, by defining
Flora
Since the habitat of alpine vegetation is subject to intense radiation, wind, cold, snow, and ice, it grows close to the ground and consists mainly of
Relative to lower elevation areas in the same region, alpine regions have a high rate of
Though tundra covers only a minority of the Earth's surface (17-20%), the biodiversity of plant species is important to human nutrition. Of the 20 plant species that make up 80% of human food, 7 of them (35%) originated in this region.[13]
Plants have adapted to the harsh alpine environment. Cushion plants, looking like ground-hugging clumps of moss, escape the strong winds blowing a few inches above them. Many flowering plants of the alpine tundra have dense hairs on stems and leaves to provide wind protection or red-colored pigments capable of converting the sun's light rays into heat. Some plants take two or more years to form flower buds, which survive the winter below the surface and then open and produce fruit with seeds in the few weeks of summer.[14] In various areas of alpine tundra, woody plant encroachment is observed.[15][16][17]
Alpine areas are unique because of the severity and complexity of their environmental conditions. Very small changes in
Alpine meadows form where sediments from the weathering of rocks has produced soils well-developed enough to support grasses and sedges. Non-flowering
Fauna
Because alpine tundra is located in various widely separated regions of the Earth, there is no animal species common to all areas of alpine tundra. Some animals of alpine tundra environments include the kea, marmot, mountain goat, bighorn sheep, chinchilla, Himalayan tahr, yak, snow leopard, and pika.[18]
See also
- Montane grasslands and shrublands
- Urals montane tundra and taiga
- Polonyna (montane meadow)
- Montane ecosystems
- Tundra
References
- ISBN 978-1-925039-32-0. Retrieved 2023-07-05.
- ^ "The Alpine Biome". Archived from the original on 19 January 2010. Retrieved 2009-12-19.
- ISSN 0362-4331. Retrieved 2021-05-31.
- ^ "South Island montane grasslands". Terrestrial Ecoregions. World Wildlife Fund.
- JSTOR 3683770.
- PMID 26811780.
- ^ a b c d This article incorporates public domain material from Grassland Habitat Group (PDF). Bureau of Land Management. Archived from the original (PDF) on 2008-07-24.
- S2CID 8647814. Archived from the original(PDF) on 2006-09-11. Retrieved 2018-07-30.
- ISBN 978-1-899628-20-9. Archived from the original(PDF) on 2013-10-14.
- ISBN 978-0-521-55986-7.
- ^ "Biodiversity lectures and practicals of Allan Jones". dundee.ac.uk. Archived from the original on 2007-09-29.
- ^ S2CID 41723233.
- ISBN 978-1-77041-435-8.
- ^ a b This article incorporates public domain material from Rocky Mountain National Park: Alpine Tundra Ecosystem. National Park Service.
- S2CID 225314620.
- JSTOR 1478919.
- S2CID 245267638.
- ^ "The tundra biome". ucmp.berkeley.edu. Retrieved 2023-12-31.
External links
- Media related to Alpine tundra at Wikimedia Commons