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 .
32-411: 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
64-617: A boundary between species due to the obstructive nature of their terrain . Mont Ventoux in France is a good example, marking the boundary between the flora and fauna of northern and southern France . Most wetlands are ecotones. The spatial variation of ecotones often form due to disturbances, creating patches that separate patches of vegetation. Different intensity of disturbances can cause landslides, land shifts, or movement of sediment that can create these vegetation patches and ecotones. Plants in competition extend themselves on one side of
96-406: A distinct line between two communities. For example, a change in colors of grasses or plant life can indicate an ecotone. Second, a change in physiognomy (physical appearance of a plant species) can be a key indicator. Water bodies, such as estuaries, can also have a region of transition, and the boundary is characterized by the differences in heights of the macrophytes or plant species present in
128-473: A diverse ecosystem. Changes in the physical environment may produce a sharp boundary , as in the example of the interface between areas of forest and cleared land . Elsewhere, a more gradually blended interface area will be found, where species from each community will be found together as well as unique local species. Mountain ranges often create such ecotones, due to the wide variety of climatic conditions experienced on their slopes . They may also provide
160-490: A doctorate in geology in 1894, and later became a lecturer and then associate professor in the university's geology department. Otto Nordenskjöld led mineralogical expeditions to Patagonia in the 1890s, and to Alaska and the Klondike area in 1898. Nordenskjöld led the 1901–1904 Swedish Antarctic Expedition . Their ship Antarctic , commanded by the seasoned Antarctic sailor Carl Anton Larsen , visited Buenos Aires and
192-672: A few inches tall, with weak root systems. Other common plant life-forms include prostrate shrubs ; tussock -forming graminoids ; cushion plants ; and cryptogams , such as bryophytes and lichens . 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. These phenomena contribute to plant diversity by introducing new flora and favoring adaptations , both of new species and
224-450: 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
256-630: A mountain is roughly equivalent to moving 80 kilometers (45 miles or 0.75° of latitude) towards the pole. 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). 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
288-744: A number of highly adaptable species that tend to colonize such transitional areas. The phenomenon of increased variety of plants as well as animals at the community junction is called the edge effect and is essentially due to a locally broader range of suitable environmental conditions or ecological niches . An ecotone is often associated with an ecocline : a "physical transition zone" between two systems. The ecotone and ecocline concepts are sometimes confused: an ecocline can signal an ecotone chemically (ex: pH or salinity gradient ), or microclimatically ( hydrothermal gradient) between two ecosystems. In contrast: Otto Nordenskj%C3%B6ld Nils Otto Gustaf Nordenskjöld (6 December 1869 – 2 June 1928)
320-450: 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
352-546: 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. 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,
SECTION 10
#1732847463402384-431: Is a transition area between two biological communities, where two communities meet and integrate. It may be narrow or wide, and it may be local (the zone between a field and forest) or regional (the transition between forest and grassland ecosystems ). An ecotone may appear on the ground as a gradual blending of the two communities across a broad area, or it may manifest itself as a sharp boundary line. The word ecotone
416-453: Is observed. 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
448-841: The Falkland Islands before leaving Nordenskjöld's party at Snow Hill Island off the Antarctic Peninsula to overwinter, while the ship returned to the Falklands. The following spring, early in November 1902, Larsen sailed south to retrieve the party, but the Antarctic became trapped in ice and so damaged it eventually sank on 12 February 1903, forcing the crew to winter in a hastily constructed shelter on Paulet Island . Larsen and Nordenskjöld finally rendezvoused at their fall-back rescue hut at Hope Bay in November 1903 and were soon picked up by
480-495: 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 . 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
512-532: The areas because this distinguishes the two areas' accessibility to light. Scientists look at color variations and changes in plant height. Third, a change of species can signal an ecotone. There will be specific organisms on one side of an ecotone or the other. Other factors can illustrate or obscure an ecotone, for example, migration and the establishment of new plants. These are known as spatial mass effects, which are noticeable because some organisms will not be able to form self-sustaining populations if they cross
544-440: 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 :
576-513: The bogs and along the brooks. 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
608-719: The corvette ARA Uruguay (commanded by Julián Irízar ), dispatched after Antarctic had failed to make its appointed return to Argentina. Despite its end and the great hardships endured, the expedition was considered a scientific success, having explored much of the eastern coast of Graham Land , including Cape Longing , James Ross Island , the Joinville Island group , and the Palmer Archipelago , recovering also valuable geological samples and samples of marine animals. It earned Nordenskjöld lasting fame at home, but its huge cost left him greatly in debt. In 1905, Nordenskjöld
640-450: The dispersal of pre-existing species. 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. Plants have adapted to the harsh alpine environment. Cushion plants , looking like ground-hugging clumps of moss, escape
672-419: The ecotone as far as their ability to maintain themselves allows. Beyond this competitors of the adjacent community take over. As a result, the ecotone represents a shift in dominance. Ecotones are particularly significant for mobile animals, as they can exploit more than one set of habitats within a short distance. The ecotone contains not only species common to the communities on both sides; it may also include
SECTION 20
#1732847463402704-540: The ecotone. If different species can survive in both communities of the two biomes, then the ecotone is considered to have species richness ; ecologists measure this when studying the food chain and success of organisms. Lastly, the abundance of introduced species in an ecotone can reveal the type of biome or efficiency of the two communities sharing space. Because an ecotone is the zone in which two communities integrate, many different forms of life have to live together and compete for space. Therefore, an ecotone can create
736-488: 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
768-770: 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 . There have been several attempts at quantifying what constitutes an alpine climate. Climatologist Wladimir Köppen demonstrated
800-399: 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), Holdridge quantifies the climate as alpine. Since the habitat of alpine vegetation is subject to intense radiation, wind, cold, snow, and ice, it grows close to
832-832: 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, the South Island of New Zealand, and the Scandinavian Mountains . Alpine tundra occupies high-mountain summits, slopes, and ridges above timberline. Aspect plays
864-467: 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. In various areas of alpine tundra, woody plant encroachment
896-505: The treeline is roughly constant, between 3,500 and 4,000 meters (11,500 and 13,100 ft). 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
928-503: The tundra is very fragile. Repeated footsteps often destroy tundra plants, allowing exposed soil to blow away; recovery may take hundreds of years. 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 . Ecotone An ecotone
960-607: Was a Swedish geologist, geographer, and polar explorer . Nordenskjöld was born in Hässleby in Småland in eastern Sweden, in a family that included his maternal uncle, the polar explorer Adolf Erik Nordenskiöld , and cousin Gustaf Nordenskiöld . His father and mother were cousins, but his father's family name was "Nordenskjöld", while his mother's family name was spelled "Nordenskiöld". He studied at Uppsala University , obtaining
992-525: Was appointed professor of geography (with commercial geography) and ethnography at University of Gothenburg . Nordenskjöld later explored Greenland in 1909 and returned to South America to explore Chile and Peru in the early 1920s (many samples from this expedition are now displayed at the Natural History Museum in Lima ). He also studied the effects of winter on alpine climate , and developed
Alpine tundra - Misplaced Pages Continue
1024-478: Was coined (and its etymology given) in 1904 in "The Development and Structure of Vegetation" (Lincoln, Nebraska: Botanical Seminar) by Frederic E. Clements. It is formed as a combination of ecology plus -tone , from the Greek tonos or tension – in other words, a place where ecologies are in tension. There are several distinguishing features of an ecotone. First, an ecotone can have a sharp vegetation transition, with
#401598