Alpine tundra

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Hikers traversing the Franconia Ridge in the White Mountains of New Hampshire, much of which is in the alpine zone. Hikers on franconia ridge.JPG
Hikers traversing the Franconia Ridge in the White Mountains of New Hampshire, much of which is in the alpine zone.
Alpine tundra in the Venezuelan Andes Valle de Mifafi 3.jpg
Alpine tundra in the Venezuelan Andes

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.

Contents

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 adiabatic cooling of air, and is similar to polar climate.

Geography

Alpine tundra occurs at high enough altitude at any latitude. Portions of montane grasslands and shrublands ecoregions worldwide include alpine tundra. Large regions of alpine tundra occur in the North American Cordillera and parts of the northern Appalachian Mountains in North America, the Alps and Pyrenees of Europe, the Himalaya and Karakoram of Asia, the Andes of South America, the Eastern Rift mountains of Africa, the Snowy Mountains of Australia, [1] the South Island of New Zealand, [2] [3] [4] and the Scandinavian Mountains. [5] [6]

Alpine tundra occupies high-mountain summits, slopes, and ridges above timberline. Aspect plays a role as well; the treeline often occurs at higher elevations on warmer equator-facing slopes. Because the alpine zone is present only on mountains, much of the landscape is rugged and broken, with rocky, snowcapped peaks, cliffs, and talus slopes, but also contains areas of gently rolling to almost flat topography. [7]

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

Summer in Northern Sweden's Tarfala Valley with its alpine climate Tarfala Valley - Sweden.jpg
Summer in Northern Sweden's Tarfala Valley with its alpine climate

Alpine climate is the average weather (climate) for the alpine tundra. The climate becomes colder when reaching higher elevations—this characteristic is described by the lapse rate of air: air tends to get colder as it rises, since it expands. The dry adiabatic lapse rate is 10 °C per km (5.5 °F per 1000 ft) of elevation or altitude. Therefore, moving up 100 meters (330 ft) on a mountain is roughly equivalent to moving 80 kilometers (45 miles or 0.75° of latitude) towards the pole. [9] This relationship is only approximate, however, since local factors such as proximity to oceans can drastically modify the climate.

In the alpine tundra, trees cannot tolerate the environmental conditions (usually cold temperatures, extreme snowpack, or associated lack of available moisture). [10] : 51  Typical high-elevation growing seasons range from 45 to 90 days, with average summer temperatures near 10 °C (50 °F). Growing season temperatures frequently fall below freezing, and frost occurs throughout the growing season in many areas. Precipitation occurs mainly as winter snow, but soil water availability is highly variable with season, location, and topography. For example, snowfields commonly accumulate on the lee sides of ridges while ridgelines may remain nearly snow free due to redistribution by wind. Some alpine habitats may be up to 70% snow free in winter. High winds are common in alpine ecosystems, and can cause significant soil erosion and be physically and physiologically detrimental to plants. Also, wind coupled with high solar radiation can promote extremely high rates of evaporation and transpiration. [7]

Quantifying the climate

Alpine tundra just above the tree line in Kosciuszko National Park, Australia Snezne hory - Snowy River - panoramio.jpg
Alpine tundra just above the tree line in Kosciuszko National Park, Australia

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 biotemperature: the mean annual temperature, where all temperatures below 0 °C are treated as 0 °C (because it makes no difference to plant life, being dormant). If the mean biotemperature is between 1.5 and 3 °C (34.7 and 37.4 °F), [11] Holdridge quantifies the climate as alpine.

Flora

Silky phacelia (Phacelia sericea, blooming) and spreading phlox (Phlox diffusa) are species of alpine regions of western North America. Phacelia sericea 4793.JPG
Silky phacelia ( Phacelia sericea , blooming) and spreading phlox ( Phlox diffusa ) are species of alpine regions of western North America.

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 perennial grasses, sedges, and forbs. Perennial herbs (including grasses, sedges, and low woody or semi-woody shrubs) dominate the alpine landscape; they have much more root and rhizome biomass than that of shoots, leaves, and flowers. The roots and rhizomes not only function in water and nutrient absorption but also play a very important role in over-winter carbohydrate storage. Annual plants are rare in this ecosystem and usually are only a few inches tall, with weak root systems. [7] Other common plant life-forms include prostrate shrubs; tussock-forming graminoids; cushion plants; and cryptogams, such as bryophytes and lichens. [12]

Relative to lower elevation areas in the same region, alpine regions have a high rate of endemism and a high diversity of plant species. This taxonomic diversity can be attributed to geographical isolation, climate changes, glaciation, microhabitat differentiation, and different histories of migration or evolution or both. [12] These phenomena contribute to plant diversity by introducing new flora and favoring adaptations, both of new species and the dispersal of pre-existing species. [12]

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]

Alpine flora at 11,500 feet (3500 m) on the Flat Tops plateau in the Colorado Rocky Mountains U.S.A Flat Tops tundra.jpg
Alpine flora at 11,500 feet (3500 m) on the Flat Tops plateau in the Colorado Rocky Mountains U.S.A

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 topography – as small as 1 foot (0.3 m) or less – may mean the difference between a windswept area or an area of snow accumulation, changing the potential productivity and plant community drastically. Between these extremes of drought versus saturation, several intermediate environments may exist all within a few yards of each other, depending on topography, substrate, and climate. Alpine vegetation generally occurs in a mosaic of small patches with widely differing environmental conditions. Vegetation types vary from cushion and rosette plants on the ridges and in the rock crannies; to herbaceous and grassy vegetation along the slopes; dwarf shrubs with grasses and forbs below the melting snowdrifts; and sedges, grasses, low shrubs, and mosses in the bogs and along the brooks. [7]

An alpine mire in the Swiss Alps GlarusAlps.jpg
An alpine mire in the Swiss Alps

Alpine meadows form where sediments from the weathering of rocks has produced soils well-developed enough to support grasses and sedges. Non-flowering lichens cling to rocks and soil. Their enclosed algal cells can photosynthesize at any temperature above 0 °C (32 °F), and the outer fungal layers can absorb more than their own weight in water. The adaptations for survival of drying winds and cold may make tundra vegetation seem very hardy, but in some respects the tundra is very fragile. Repeated footsteps often destroy tundra plants, allowing exposed soil to blow away; recovery may take hundreds of years. [14]

Fauna

The Himalayan tahr Himalaja-Tahr.JPG
The Himalayan tahr

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

Related Research Articles

<span class="mw-page-title-main">Biome</span> Biogeographical unit with a particular biological community

A biome is a distinct geographical region with specific climate, vegetation, and animal life. It consists of a biological community that has formed in response to its physical environment and regional climate. Biomes may span more than one continent. A biome encompasses multiple ecosystems within its boundaries. It can also comprise a variety of habitats.

<span class="mw-page-title-main">Tundra</span> Biome where plant growth is hindered by frigid temperatures

In physical geography, tundra is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. There are three regions and associated types of tundra: Arctic tundra, alpine tundra, and Antarctic tundra.

<span class="mw-page-title-main">Grassland</span> Area with vegetation dominated by grasses

A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur naturally on all continents except Antarctica and are found in most ecoregions of the Earth. Furthermore, grasslands are one of the largest biomes on Earth and dominate the landscape worldwide. There are different types of grasslands: natural grasslands, semi-natural grasslands, and agricultural grasslands. They cover 31–69% of the Earth's land area.

<span class="mw-page-title-main">Montane grasslands and shrublands</span> Biome defined by the World Wildlife Fund

Montane grasslands and shrublands are a biome defined by the World Wildlife Fund. The biome includes high elevation grasslands and shrublands around the world. The term "montane" in the name of the biome refers to "high elevation", rather than the ecological term that denotes the region below the treeline.

<span class="mw-page-title-main">Great Basin Desert</span> Desert in the western United States

The Great Basin Desert is part of the Great Basin between the Sierra Nevada and the Wasatch Range. The desert is a geographical region that largely overlaps the Great Basin shrub steppe defined by the World Wildlife Fund, and the Central Basin and Range ecoregion defined by the U.S. Environmental Protection Agency and United States Geological Survey. It is a temperate desert with hot, dry summers and snowy winters. The desert spans large portions of Nevada and Utah, and extends into eastern California. The desert is one of the four biologically defined deserts in North America, in addition to the Mojave, Sonoran, and Chihuahuan Deserts.

<span class="mw-page-title-main">Tree line</span> Edge of the habitat at which trees are capable of growing

The tree line is the edge of a habitat at which trees are capable of growing and beyond which they are not. 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, which is the line below which trees form a forest with a closed canopy.

<span class="mw-page-title-main">Rangeland</span> Biomes which can be grazed by animals or livestock (grasslands, woodlands, prairies, etc)

Rangelands are grasslands, shrublands, woodlands, wetlands, and deserts that are grazed by domestic livestock or wild animals. Types of rangelands include tallgrass and shortgrass prairies, desert grasslands and shrublands, woodlands, savannas, chaparrals, steppes, and tundras. Rangelands do not include forests lacking grazable understory vegetation, barren desert, farmland, or land covered by solid rock, concrete, or glaciers.

<span class="mw-page-title-main">Alpine plant</span> Plants that grow at high elevation

Alpine plants are plants that grow in an alpine climate, which occurs at high elevation and above the tree line. There are many different plant species and taxa that grow as a plant community in these alpine tundra. These include perennial grasses, sedges, forbs, cushion plants, mosses, and lichens. Alpine plants are adapted to the harsh conditions of the alpine environment, which include low temperatures, dryness, ultraviolet radiation, wind, drought, poor nutritional soil, and a short growing season.

<span class="mw-page-title-main">Páramo</span> High-altitude wet tundra in South America

Páramo may refer to a variety of alpine tundra ecosystems located in the Andes Mountain Range, South America. Some ecologists describe the páramo broadly as "all high, tropical, montane vegetation above the continuous timberline". A narrower term classifies the páramo according to its regional placement in the northern Andes of South America and adjacent southern Central America. The páramo is the ecosystem of the regions above the continuous forest line, yet below the permanent snowline. It is a "Neotropical high mountain biome with a vegetation composed mainly of giant rosette plants, shrubs and grasses". According to scientists, páramos may be "evolutionary hot spots", meaning that it's among the fastest evolving regions on Earth.

<span class="mw-page-title-main">Life zones of Peru</span>

When the Spanish arrived, they divided Peru into three main regions: the coastal region, that is bounded by the Pacific Ocean; the highlands, that is located on the Andean Heights, and the jungle, that is located on the Amazonian Jungle. But Javier Pulgar Vidal, a geographer who studied the biogeographic reality of the Peruvian territory for a long time, proposed the creation of eight Natural Regions. In 1941, he presented his thesis "Las Ocho Regiones Naturales del Perú" at the III General Assembly of the Pan-American Institute of Geography and History.

<span class="mw-page-title-main">Scandinavian montane birch forest and grasslands</span> Tundra ecoregion in Scandinavia

The Scandinavian montane birch forests and grasslands is defined by the World Wildlife Fund (WWF) as a terrestrial tundra ecoregion in Norway, Sweden, and Finland.

<span class="mw-page-title-main">Puna grassland</span> Type of grassland in the central part of the high Andes

The puna grassland ecoregion, part of the Andean montane grasslands and shrublands biome, is found in the central Andes Mountains of South America. It is considered one of the eight Natural Regions in Peru, but extends south, across Chile, Bolivia, and western northwest Argentina. The term puna encompasses diverse ecosystems of the high Central Andes above 3200–3400 m.

<span class="mw-page-title-main">Sierra Nevada subalpine zone</span> Biotic zone in California, United States

The Sierra Nevada subalpine zone refers to a biotic zone below treeline in the Sierra Nevada mountain range of California, United States. This subalpine zone is positioned between the upper montane zone at its lower limit, and tree line at its upper limit.

<span class="mw-page-title-main">Arctic vegetation</span> Plants adapted to the short, cold growing seasons of the Arctic regions

About 1,702 species of plants live on the Arctic tundra, including flowering plants, short shrubs, herbs, grasses, and mosses. These plants are adapted to short, cold growing seasons. They have the ability to withstand extremely cold temperatures in the winter, and grow and reproduce in summer conditions that are quite limiting.

Altitudinal zonation in mountainous regions describes the natural layering of ecosystems that occurs at distinct elevations due to varying environmental conditions. Temperature, humidity, soil composition, and solar radiation are important factors in determining altitudinal zones, which consequently support different vegetation and animal species. Altitudinal zonation was first hypothesized by geographer Alexander von Humboldt who noticed that temperature drops with increasing elevation. Zonation also occurs in intertidal and marine environments, as well as on shorelines and in wetlands. Scientist C. Hart Merriam observed that changes in vegetation and animals in altitudinal zones map onto changes expected with increased latitude in his concept of life zones. Today, altitudinal zonation represents a core concept in mountain research.

<span class="mw-page-title-main">Ecology of the North Cascades</span> Ecosystems of the Cascade mountain range in northern Washington state and southern British Columbia

The Ecology of the North Cascades is heavily influenced by the high elevation and rain shadow effects of the mountain range. The North Cascades is a section of the Cascade Range from the South Fork of the Snoqualmie River in Washington, United States, to the confluence of the Thompson and Fraser Rivers in British Columbia, Canada, where the range is officially called the Cascade Mountains but is usually referred to as the Canadian Cascades. The North Cascades Ecoregion is a Level III ecoregion in the Commission for Environmental Cooperation's classification system.

<span class="mw-page-title-main">Montane ecosystems</span> Ecosystems found in mountains

Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial factor in shaping plant community, biodiversity, metabolic processes and ecosystem dynamics for montane ecosystems. Dense montane forests are common at moderate elevations, due to moderate temperatures and high rainfall. At higher elevations, the climate is harsher, with lower temperatures and higher winds, preventing the growth of trees and causing the plant community to transition to montane grasslands and shrublands or alpine tundra. Due to the unique climate conditions of montane ecosystems, they contain increased numbers of endemic species. Montane ecosystems also exhibit variation in ecosystem services, which include carbon storage and water supply.

<span class="mw-page-title-main">Northern Andean páramo</span>

The Northern Andean páramo (NT1006) is an ecoregion containing páramo vegetation above the treeline in the Andes of Colombia and Ecuador. In the past, when the climate was cooler, the treeline and the páramo units were lower and the units were connected. During the present warmer Holocene epoch the páramos have migrated uphill, shrinking and becoming isolated. They contain many rare or endangered species, some of them restricted to a narrow area of one mountain or mountain range. The ecoregion is relatively well preserved, but faces threats from over-grazing and farming.

<span class="mw-page-title-main">Altai alpine meadow and tundra</span> Ecoregion in the Altai Mountains

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 realm, with a humid continental climate. It covers an area of 90,132 square kilometres (34,800 sq mi).

<span class="mw-page-title-main">Tundra of North America</span>

The Tundra of North America is a Level I ecoregion of North America designated by the Commission for Environmental Cooperation (CEC) in its North American Environmental Atlas.

References

  1. ↑ Pickering, Catherine; Venn, Susanna. Increasing the resilience of the Australian alpine flora to climate change and associated threats: A plant functional traits approach (PDF) (Report). Gold Coast: National Climate Change Adaptation Research Facility. ISBN   978-1-925039-32-0 . Retrieved 2023-07-05.
  2. ↑ "The Alpine Biome". Archived from the original on 19 January 2010. Retrieved 2009-12-19.
  3. ↑ Regenold, Stephen (2007-10-12). "A Pocket of Alpine Tundra Nestled Atop New England". The New York Times. ISSN   0362-4331 . Retrieved 2021-05-31.
  4. ↑ "South Island montane grasslands". Terrestrial Ecoregions. World Wildlife Fund.
  5. ↑ Austrheim, Gunnar; Eriksson, Ove (2001). "Plant Species Diversity and Grazing in the Scandinavian Mountains: Patterns and Processes at Different Spatial Scales". Ecography. 24 (6): 683–695. doi:10.1034/j.1600-0587.2001.240607.x. JSTOR   3683770.
  6. ↑ Virtanen, Risto; Oksanen, Lauri; Oksanen, Tarja; Cohen, Juval; Forbes, Bruce C.; Johansen, Bernt; Käyhkö, Jukka; Olofsson, Johan; Pulliainen, Jouni; Tømmervik, Hans (2016). "Where do the treeless tundra areas of northern highlands fit in the global biome system: Toward an ecologically natural subdivision of the tundra biome". Ecology and Evolution. 6 (1): 143–158. doi:10.1002/ece3.1837. PMC   4716497 . PMID   26811780.
  7. 1 2 3 4 PD-icon.svg This article incorporates public domain material from Grassland Habitat Group (PDF). Bureau of Land Management. Archived from the original (PDF) on 2008-07-24.
  8. ↑ Körner, Ch (1998). "A re-assessment of high elevation treeline positions and their explanation" (PDF). Oecologia. 115 (4): 445–459. Bibcode:1998Oecol.115..445K. CiteSeerX   10.1.1.454.8501 . doi:10.1007/s004420050540. PMID   28308263. S2CID   8647814. Archived from the original (PDF) on 2006-09-11. Retrieved 2018-07-30.
  9. ↑ Blyth, S; Groombridge, B.; Lysenko, I; Miles, L.; Newton, A (2002). Mountain Watch: environmental change & sustainable development in mountains (PDF). UNEP World Conservation Monitoring Centre. ISBN   978-1-899628-20-9. Archived from the original (PDF) on 2013-10-14.
  10. ↑ Elliott-Fisk, D.L. (2000). "The Taiga and Boreal Forest". In Barbour, M.G.; Billings, M.D. (eds.). North American Terrestrial Vegetation (2nd ed.). Cambridge University Press. ISBN   978-0-521-55986-7.
  11. ↑ "Biodiversity lectures and practicals of Allan Jones". dundee.ac.uk. Archived from the original on 2007-09-29.
  12. 1 2 3 Körner, Christian (2003). Alpine Plant Life: Functional Plant Ecology of High Mountain Ecosystems. Berlin: Springer. pp. 9–18. doi:10.1007/978-3-642-18970-8. ISBN   978-3-540-00347-2. S2CID   41723233.
  13. ↑ Newman, Lenore (2019). Lost Feast: Culinary Extinction and the future of food. Toronto: ECW Press. pp. 171–172. ISBN   978-1-77041-435-8.
  14. 1 2 PD-icon.svg This article incorporates public domain material from Rocky Mountain National Park: Alpine Tundra Ecosystem. National Park Service.
  15. ↑ Marsman, Floor; Nystuen, Kristin O.; Opedal, Øystein H.; Foest, Jessie J.; Sørensen, Mia Vedel; De Frenne, Pieter; Graae, Bente Jessen; Limpens, Juul (January 2021). Pugnaire, Francisco (ed.). "Determinants of tree seedling establishment in alpine tundra". Journal of Vegetation Science. 32 (1). doi: 10.1111/jvs.12948 . hdl: 1854/LU-8741393 . ISSN   1100-9233. S2CID   225314620.
  16. ↑ Rosén, Ejvind; van der Maarel, Eddy (May 2000). "Restoration of alvar vegetation on Öland, Sweden". Applied Vegetation Science. 3 (1): 65–72. doi:10.2307/1478919. ISSN   1402-2001. JSTOR   1478919.
  17. ↑ Hallman, Cassandra; Olsson, Ola; Tyler, Torbjörn (January 2022). "Changes in south-Swedish vegetation composition over the last 200 years". Ecological Indicators. 134: 108486. doi: 10.1016/j.ecolind.2021.108486 . ISSN   1470-160X. S2CID   245267638.
  18. ↑ "The tundra biome". ucmp.berkeley.edu. Retrieved 2023-12-31.
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