Alpine tundra

<h2 id="geography">Geography</h2>
Alpine tundra occurs at high enough altitude at any <a href="/facts/Latitude/IBYqkjhU">latitude</a>. Portions of <a href="/facts/Montane_grasslands_and_shrublands/RkCSWTAG">montane grasslands and shrublands</a> ecoregions worldwide include alpine tundra. Large regions of alpine tundra occur in the <a href="/facts/North_American_Cordillera/xxDydVll">North American Cordillera</a> and parts of the northern <a href="/facts/Appalachian_Mountains/f7X1GBDE">Appalachian Mountains</a> in North America, the <a href="/facts/Alps/Q3zdQId4">Alps</a> and <a href="/facts/Pyrenees/YJ38kInj">Pyrenees</a> of Europe, the <a href="/facts/Himalaya/eRSf0yyE">Himalaya</a> and <a href="/facts/Karakoram/hTjgf9go">Karakoram</a> of Asia, the <a href="/facts/Andes/a4wlgG3e">Andes</a> of South America, the <a href="/facts/Eastern_Rift_mountains/wPBqf329">Eastern Rift mountains</a> of Africa, the <a href="/facts/Snowy_Mountains/JvBM7ReN">Snowy Mountains</a> of Australia,<a class="footnote-ref" id="fnref:1" href="#fn:1">1</a> the <a href="/facts/South_Island/asD6NsNx">South Island</a> of New Zealand,<a class="footnote-ref" id="fnref:2" href="#fn:2">2</a><a class="footnote-ref" id="fnref:3" href="#fn:3">3</a><a class="footnote-ref" id="fnref:4" href="#fn:4">4</a> and the <a href="/facts/Scandinavian_Mountains/lAWdP0Tr">Scandinavian Mountains</a>.<a class="footnote-ref" id="fnref:5" href="#fn:5">5</a><a class="footnote-ref" id="fnref:6" href="#fn:6">6</a>
Alpine tundra occupies high-mountain summits, slopes, and ridges above timberline. Aspect plays a role as well; the <a href="/facts/Treeline/ANIlSVby">treeline</a> 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.<a class="footnote-ref" id="fnref:7" href="#fn:7">7</a>
Averaging over many locations and local <a href="/facts/Microclimate/CGSzXfJ3">microclimates</a>, 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).<a class="footnote-ref" id="fnref:8" href="#fn:8">8</a>

<h2 id="climate">Climate</h2>

<a href="/facts/Alpine_climate/wUdLLA3b">Alpine climate</a> is the average weather (<a href="/facts/Climate/f57XrNFU">climate</a>) for the alpine tundra. The climate becomes colder when reaching higher <a href="/facts/Elevation/h2d0u9nd">elevations</a>—this characteristic is described by the <a href="/facts/Adiabatic_lapse_rate/FNyP1EjM">lapse rate</a> of air: air tends to get colder as it rises, since it expands. The <a href="/facts/Adiabatic_lapse_rate/FNyP1EjM">dry adiabatic lapse rate</a> is 10 °C per km (5.5 °F per 1000 ft) of elevation or <a href="/facts/Altitude/B5eNVurK">altitude</a>. 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.<a class="footnote-ref" id="fnref:9" href="#fn:9">9</a> This relationship is only approximate, however, since local factors such as proximity to <a href="/facts/Ocean/8W8lYgjD">oceans</a> 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).<a class="footnote-ref" id="fnref:10" href="#fn:10">10</a>: 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. <a href="/facts/Precipitation_(meteorology)/uq3nGQc8">Precipitation</a> occurs mainly as winter snow, but soil water availability is highly variable with season, location, and topography. For example, <a href="/facts/Snowfield/cS3877el">snowfields</a> 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 <a href="/facts/Wind/Nt0QIu5B">winds</a> are common in alpine ecosystems, and can cause significant soil erosion and be physically and physiologically detrimental to plants. Also, wind coupled with high <a href="/facts/Solar_radiation/SI26I7aD">solar radiation</a> can promote extremely high rates of <a href="/facts/Evaporation/tgvIlJys">evaporation</a> and <a href="/facts/Transpiration/XvBpcDbB">transpiration</a>.<a class="footnote-ref" id="fnref:11" href="#fn:11">11</a>

<h3>Quantifying the climate</h3>

There have been several attempts at quantifying what constitutes an alpine climate.
Climatologist <a href="/facts/Wladimir_K%25C3%25B6ppen/zfC8NKfx">Wladimir Köppen</a> 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 <a href="/facts/K%25C3%25B6ppen_climate_classification/VDcr86hF">Köppen climate classification</a> for more information.
<a href="/facts/Otto_Nordenskj%25C3%25B6ld/pIAodX15">Otto Nordenskjöld</a> 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 <a href="/facts/Biotemperature/K7Wyc5fk">biotemperature</a>: 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),<a class="footnote-ref" id="fnref:12" href="#fn:12">12</a> Holdridge quantifies the climate as alpine.

<h2 id="flora">Flora</h2>
Main article: <a href="/facts/Alpine_plant/Qxkk0tHP">Alpine plant</a>

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 <a href="/facts/Perennial_grass/MQ3NvAUW">perennial grasses</a>, <a href="/facts/Cyperaceae/A1oI2H0U">sedges</a>, and <a href="/facts/Forb/G6S7e8E6">forbs</a>. Perennial herbs (including <a href="/facts/Poaceae/q2CRK8q0">grasses</a>, <a href="/facts/Cyperaceae/A1oI2H0U">sedges</a>, and low woody or semi-woody <a href="/facts/Shrub/X1gKVxL5">shrubs</a>) dominate the alpine landscape; they have much more <a href="/facts/Root/x2U60Gdm">root</a> and <a href="/facts/Rhizome/wWDKJrSf">rhizome</a> 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.<a class="footnote-ref" id="fnref:13" href="#fn:13">13</a> Other common <a href="/facts/Plant_life-form/IjSdInAK">plant life-forms</a> include <a href="/facts/Prostrate_shrub/7WgVw2Jm">prostrate shrubs</a>; <a href="/facts/Tussock_(grass)/Ap0au59e">tussock</a>-forming <a href="/facts/Graminoid/UsR1g55c">graminoids</a>; <a href="/facts/Cushion_plants/KaGvDdFT">cushion plants</a>; and <a href="/facts/Cryptogam/M09JIxcs">cryptogams</a>, such as <a href="/facts/Bryophyte/DWXKNQ1h">bryophytes</a> and <a href="/facts/Lichen/cfbt9vjj">lichens</a>.<a class="footnote-ref" id="fnref:14" href="#fn:14">14</a>
Relative to lower elevation areas in the same region, alpine regions have a high rate of <a href="/facts/Endemism/xt4IpIsl">endemism</a> and a high diversity of plant species. This <a href="/facts/Taxonomy_(biology)/Qkg8wuyw">taxonomic</a> diversity can be attributed to <a href="/facts/Geographical_isolation/H6K8mSDf">geographical isolation</a>, <a href="/facts/Climate_change_(general_concept)/D3X6Ulbu">climate changes</a>, <a href="/facts/Glacial_period/alIAm38r">glaciation</a>, <a href="/facts/Microenvironment_(ecology)/zo1DN2gA">microhabitat</a> differentiation, and different histories of <a href="/facts/Seed_dispersal/yNofEeyA">migration</a> or <a href="/facts/Evolution/Hj0qAaBk">evolution</a> or both.<a class="footnote-ref" id="fnref:15" href="#fn:15">15</a> These phenomena contribute to plant diversity by introducing new flora and favoring <a href="/facts/Adaptations/5K2gNpDB">adaptations</a>, both of new species and the dispersal of pre-existing species.<a class="footnote-ref" id="fnref:16" href="#fn:16">16</a>
Though tundra covers only a minority of the Earth's surface (17-20%), the <a href="/facts/Biodiversity/GruakEzs">biodiversity</a> 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.<a class="footnote-ref" id="fnref:17" href="#fn:17">17</a>

Plants have adapted to the harsh alpine environment. <a href="/facts/Cushion_plant/KaGvDdFT">Cushion plants</a>, 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 <a href="/facts/Anthocyanin/eUY12Frv">red-colored pigments</a> 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.<a class="footnote-ref" id="fnref:18" href="#fn:18">18</a> In various areas of alpine tundra, <a href="/facts/Woody_plant_encroachment/36pSLXn9">woody plant encroachment</a> is observed.<a class="footnote-ref" id="fnref:19" href="#fn:19">19</a><a class="footnote-ref" id="fnref:20" href="#fn:20">20</a><a class="footnote-ref" id="fnref:21" href="#fn:21">21</a>
Alpine areas are unique because of the severity and complexity of their environmental conditions. Very small changes in <a href="/facts/Topography/SS8Bx4t9">topography</a> – 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 <a href="/facts/Productivity/yXlzAjC2">productivity</a> and <a href="/facts/Plant_community/uoyIghLB">plant community</a> drastically. Between these extremes of <a href="/facts/Drought/LVW0rfuV">drought</a> versus <a href="/facts/Saturated_fluid/17u7zMCg">saturation</a>, 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 <a href="/facts/Shrub/X1gKVxL5">shrubs</a> with grasses and <a href="/facts/Forb/G6S7e8E6">forbs</a> below the melting snowdrifts; and <a href="/facts/Cyperaceae/A1oI2H0U">sedges</a>, <a href="/facts/Poaceae/q2CRK8q0">grasses</a>, low <a href="/facts/Shrub/X1gKVxL5">shrubs</a>, and <a href="/facts/Moss/YF8Rbf8y">mosses</a> in the <a href="/facts/Bog/LuPbb2qV">bogs</a> and along the brooks.<a class="footnote-ref" id="fnref:22" href="#fn:22">22</a>

Alpine meadows form where sediments from the weathering of rocks has produced soils well-developed enough to support grasses and sedges. Non-flowering <a href="/facts/Lichen/cfbt9vjj">lichens</a> cling to rocks and soil. Their enclosed <a href="/facts/Algae/U1ftVKU3">algal cells</a> can <a href="/facts/Photosynthesize/TMV7w693">photosynthesize</a> 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.<a class="footnote-ref" id="fnref:23" href="#fn:23">23</a>

<h2 id="fauna">Fauna</h2>

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 <a href="/facts/Kea/xJyXYrKT">kea</a>, <a href="/facts/Marmot/tCM09qRl">marmot</a>, <a href="/facts/Mountain_goat/ru74VBTI">mountain goat</a>, <a href="/facts/Bighorn_sheep/3FflaJo9">bighorn sheep</a>, <a href="/facts/Chinchilla/TASYVC7w">chinchilla</a>, <a href="/facts/Himalayan_tahr/rX1h16a5">Himalayan tahr</a>, <a href="/facts/Yak/hdERg9XQ">yak</a>, <a href="/facts/Snow_leopard/8UG3fcRq">snow leopard</a>, and <a href="/facts/Pika/4VMuW8TH">pika</a>.<a class="footnote-ref" id="fnref:24" href="#fn:24">24</a>

<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Montane_grasslands_and_shrublands/RkCSWTAG">Montane grasslands and shrublands</a></li>
<li><a href="/facts/Urals_montane_tundra_and_taiga/Lob7QyWb">Urals montane tundra and taiga</a></li>
<li><a href="/facts/Polonyna_(montane_meadow)/yPeqb1Pq">Polonyna (montane meadow)</a></li>
<li><a href="/facts/Montane_ecosystems/gXbt5Gqn">Montane ecosystems</a></li>
<li><a href="/facts/Tundra/BqC0AQ7u">Tundra</a></li></ul>

<h2 id="external-links">External links</h2>
<ul><li> Media related to Alpine tundra at Wikimedia Commons</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn: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. <a href="978-1-925039-32-0" target="_blank">978-1-925039-32-0</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></li>
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<li id="fn:18">This article incorporates public domain material from Rocky Mountain National Park: Alpine Tundra Ecosystem. National Park Service. <a href="https://www.nps.gov/aboutus/disclaimer.htm" target="_blank">https://www.nps.gov/aboutus/disclaimer.htm</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></li>
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<li id="fn:22">This article incorporates public domain material from Grassland Habitat Group (PDF). Bureau of Land Management. Archived from the original (PDF) on 2008-07-24. <a href="/wiki/Copyright_status_of_works_by_the_federal_government_of_the_United_States" target="_blank">/wiki/Copyright_status_of_works_by_the_federal_government_of_the_United_States</a> <a href="#fnref:22" class="footnote-back-ref">↩</a></li>
<li id="fn:23">This article incorporates public domain material from Rocky Mountain National Park: Alpine Tundra Ecosystem. National Park Service. <a href="https://www.nps.gov/aboutus/disclaimer.htm" target="_blank">https://www.nps.gov/aboutus/disclaimer.htm</a> <a href="#fnref:23" class="footnote-back-ref">↩</a></li>
<li id="fn:24">"The tundra biome". ucmp.berkeley.edu. Retrieved 2023-12-31. <a href="https://ucmp.berkeley.edu/exhibits/biomes/tundra.php" target="_blank">https://ucmp.berkeley.edu/exhibits/biomes/tundra.php</a> <a href="#fnref:24" class="footnote-back-ref">↩</a></li>
</ol>

Alpine tundra open-in-new

Alpine tundra