Tree line
![](https://upload.wikimedia.org/wikipedia/commons/thumb/2/24/Tree_line_above_St._Moritz.jpg/220px-Tree_line_above_St._Moritz.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Tree_line.jpg/220px-Tree_line.jpg)
Thetree lineis the edge of ahabitatat whichtreesare capable of growing and beyond which they are not. It is found at highelevationsand highlatitudes.Beyond the tree line, trees cannot tolerate the environmental conditions (usually low temperatures, extreme snowpack, or associated lack of available moisture).[1]: 51 The tree line is sometimes distinguished from a lowertimberline,which is the line below which trees form a forest with a closedcanopy.[2]: 151 [3]: 18
At the tree line, tree growth is often sparse, stunted, and deformed by wind and cold. This is sometimes known askrummholz(German for "crooked wood" ).[4]: 58
The tree line often appears well-defined, but it can be a more gradual transition. Trees grow shorter and often at lower densities as they approach the tree line, above which they are unable to grow at all.[4]: 55 Given a certain latitude, the tree line is approximately 300 to 1000 meters below the permanentsnow lineand roughly parallel to it.[5]
Causes
[edit]Due to their vertical structure, trees are more susceptible to cold than more ground-hugging forms of plants.[6]Summer warmth generally sets the limit to which tree growth can occur, for while tree lineconifersare very frost-hardy during most of the year, they become sensitive to just 1 or 2 degrees of frost in mid-summer.[7][8]A series of warm summers in the 1940s seems to have permitted the establishment of "significant numbers" of spruce seedlings above the previous treeline in the hills nearFairbanks, Alaska.[9][10]Survival depends on a sufficiency of new growth to support the tree. Wind canmechanically damage tree tissues directly,including blasting with windborne particles, and may also contribute to the desiccation offoliage,especially of shoots that project above the snow cover.[citation needed]
The actual tree line is set by the mean temperature, while the realized tree line may be affected by disturbances, such aslogging.[6]Most human activities cannot change the actual tree line, unless they affect the climate.[6]The tree line follows the line where the seasonal mean temperature is approximately 6 °C or 43 °F.[11][6]The seasonal mean temperature is taken over all days whose mean temperature is above 0.9 °C (33.6 °F). A growing season of 94 days above that temperature is required for tree growth.[12]
Types
[edit]![](https://upload.wikimedia.org/wikipedia/en/thumb/d/de/Distribution_of_Plants_in_a_Perpendicular_Direction_in_the_Torrid%2C_the_Temperate%2C_and_the_Rigid_Zones_1848_Alexander_Keith_Johnston.png/600px-Distribution_of_Plants_in_a_Perpendicular_Direction_in_the_Torrid%2C_the_Temperate%2C_and_the_Rigid_Zones_1848_Alexander_Keith_Johnston.png)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/4/4e/Bistrishko-Branishte.jpg/220px-Bistrishko-Branishte.jpg)
Several types of tree lines are defined inecologyandgeography:
Alpine
[edit]An alpine tree line is the highest elevation that sustains trees; higher up it is too cold, or the snow cover lasts for too much of the year, to sustain trees.[2]: 151 The climate above the tree line ofmountainsis called analpine climate,[13]: 21 and the habitat can be described as thealpine zone.[14]Treelines on north-facing slopes in the northern hemisphere are lower than on south-facing slopes, because the increased shade on north-facing slopes means thesnowpacktakes longer to melt. This shortens the growing season for trees.[15]: 109 In the southern hemisphere, the south-facing slopes have the shorter growing season.
The alpine tree line boundary is seldom abrupt: it usually forms a transition zone between closed forest below and treeless alpine zone above. This zone of transition occurs "near the top of the tallest peaks in the northeastern United States, high up on the giantvolcanoesin central Mexico, and on mountains in each of the 11 western states and throughout much of Canada and Alaska ".[16]Environmentally dwarfed shrubs (krummholz) commonly form the upper limit.
The decrease in air temperature with increasing elevation creates the alpine climate. The rate of decrease can vary in different mountain chains, from 3.5 °F (1.9 °C) per 1,000 feet (300 m) of elevation gain in the dry mountains of the western United States,[16]to 1.4 °F (0.78 °C) per 1,000 feet (300 m) in the moister mountains of the eastern United States.[17]Skin effects andtopographycan createmicroclimatesthat alter the general cooling trend.[18]
Compared with arctic tree lines, alpine tree lines may receive fewer than half of the number of degree days (above 10 °C (50 °F)) based on air temperature, but because solar radiation intensities are greater at alpine than at arctic tree lines the number of degree days calculated from leaf temperatures may be very similar.[16]
At the alpine tree line, tree growth is inhibited when excessive snow lingers and shortens the growing season to the point where new growth would not have time to harden before the onset of fall frost. Moderate snowpack, however, may promote tree growth by insulating the trees from extreme cold during the winter, curtailing water loss,[19]and prolonging a supply of moisture through the early part of the growing season. However, snow accumulation in sheltered gullies in theSelkirk Mountainsof southeastern British Columbia causes the tree line to be 400 metres (1,300 ft) lower than on exposed intervening shoulders.[20]
In some mountainous areas, higher elevations above thecondensationline, or on equator-facing and leeward slopes, can result in low rainfall and increased exposure to solar radiation. This dries out the soil, resulting in a localized arid environment unsuitable for trees. Many south-facing ridges of the mountains of the Western U.S. have a lower treeline than the northern faces because of increased sun exposure and aridity. Hawaii's treeline of about 8,000 ft (2,400 m) feet is also above the condensation zone and results due to a lack of moisture.[citation needed]
Exposure
[edit]Oncoastsand isolated mountains, the tree line is often much lower than in corresponding altitudes inland and in larger, more complex mountain systems, because strongwindsreduce tree growth. In addition, the lack of suitable soil, such as alongtalus slopesor exposed rock formations, prevents trees from gaining an adequate foothold and exposes them to drought and sun.
Arctic
[edit]The arctic tree line is the northernmostlatitudein theNorthern Hemispherewhere trees can grow; farther north, it is too cold all year round to sustain trees.[21]Extremely low temperatures, especially when prolonged, can freeze the internal sap of trees, killing them. In addition,permafrostin the soil can prevent trees from getting their roots deep enough for the necessary structural support.[citation needed]
Unlike alpine tree lines, the northern tree line occurs at low elevations. The arctic forest–tundra transition zone in northwestern Canada varies in width, perhaps averaging 145 kilometres (90 mi) and widening markedly from west to east,[22]in contrast with the telescoped alpine timberlines.[16]North of the arctic tree line lies the low-growingtundra,and southwards lies theboreal forest.
Two zones can be distinguished in the arctic tree line:[23][24]a forest–tundra zone of scattered patches ofkrummholzor stunted trees, with larger trees along rivers and on sheltered sites set in a matrix of tundra; and "open boreal forest" or "lichen woodland", consisting of open groves of erect trees underlain by a carpet ofCladoniaspp.lichens.[23]The proportion of trees to lichen mat increases southwards towards the "forest line", where trees cover 50 percent or more of the landscape.[16][25]
Antarctic
[edit]A southern treeline exists in theNew Zealand Subantarctic Islandsand the AustralianMacquarie Island,with places where mean annual temperatures above 5 °C (41 °F) support trees and woody plants, and those below 5 °C (41 °F) do not.[26] Another treeline exists in the southwesternmost parts of theMagellanic subpolar forestsecoregion, where the forest merges into the subantarctic tundra (termed Magellanic moorland or Magellanic tundra).[27]For example, the northern halves ofHosteandNavarinoIslands haveNothofagus antarcticaforests but the southern parts consist of moorlands and tundra.
Tree species near tree line
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/6/67/Vihren_Peak.jpg/220px-Vihren_Peak.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/9/96/Larix_gmelinii0.jpg/220px-Larix_gmelinii0.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/51/Valle_del_Frances.jpg/220px-Valle_del_Frances.jpg)
Some typical Arctic and alpine tree line tree species (note the predominance ofconifers):
Australia
[edit]- Snow gum(Eucalyptus pauciflora)
Eurasia
[edit]- Dahurian larch(Larix gmelinii)
- Macedonian pine(Pinus peuce)
- Swiss pine(Pinus cembra)
- Mountain pine(Pinus mugo)
- Arctic white birch(Betula pubescenssubsp.tortuosa)
- Rowan[28](Sorbus aucuparia)
North America
[edit]- Subalpine fir(Abies lasiocarpa)[15]: 106
- Subalpine larch(Larix lyallii)[29]
- Mountain hemlock(Tsuga mertensiana)
- Alaska yellow cedar(Chaemaecyparis nootkatensis)
- Engelmann spruce(Picea engelmannii)[15]: 106
- Whitebark pine(Pinus albicaulis)[29]
- Great Basin bristlecone pine(Pinus longaeva)
- Rocky Mountains bristlecone pine(Pinus aristata)
- Foxtail pine(Pinus balfouriana)
- Limber pine(Pinus flexilis)
- Potosi pinyon(Pinus culminicola)
- Black spruce(Picea mariana)[1]: 53
- White spruce(Picea glauca)
- Tamarack(Larix laricina)
- Hartweg's pine(Pinus hartwegii)
South America
[edit]- Antarctic beech(Nothofagus antarctica)
- Lenga beech(Nothofagus pumilio)[30]
- Alder(Alnus acuminata)
- Pino del cerro(Podocarpus parlatorei)
- Polylepis(Polylepis tarapacana)
- Eucalyptus(not native to South America but grown in large amounts in the high Andes).[31]
Worldwide distribution
[edit]Alpine tree lines
[edit]The alpine tree line at a location is dependent on local variables, such asaspectof slope,rain shadowand proximity to eithergeographical pole.In addition, in some tropical or island localities, the lack of biogeographical access to species that have evolved in asubalpineenvironment can result in lower tree lines than one might expect by climate alone.[citation needed]
Averaging over many locations and localmicroclimates,the treeline rises 75 metres (245 ft) when moving 1 degree south from 70 to 50°N, and 130 metres (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 metres (11,500 and 13,100 ft).[32]
Here is a list of approximate tree lines from locations around the globe:
Location | Approx. latitude | Approx. elevation of tree line | Notes | |
---|---|---|---|---|
(m) | (ft) | |||
Finnmarksvidda,Norway | 69°N | 500 | 1,600 | At 71°N, near the coast, the tree-line is below sea level (Arctic tree line). |
Abisko,Sweden | 68°N | 650 | 2,100 | [32] |
Chugach Mountains, Alaska | 61°N | 700 | 2,300 | Tree line around 1,500 feet (460 m) or lower in coastal areas |
Southern Norway | 61°N | 1,100 | 3,600 | Much lower near the coast, down to 500–600 metres (1,600–2,000 ft). |
Scotland, United Kingdom | 57°N | 500 | 1,600 | Strong maritime influence serves to cool summer and restrict tree growth[33]: 79 |
Northern Quebec | 56°N | 0 | 0 | The coldLabrador Currentoriginating in the arctic makes eastern Canada the sea-level region with the most southern tree-line in the northern hemisphere. |
SouthernUrals | 55°N | 1,100 | 3,600 | |
Canadian Rockies | 51°N | 2,400 | 7,900 | |
Tatra Mountains | 49°N | 1,600 | 5,200 | |
Olympic Mountains,Washington, United States | 47°N | 1,500 | 4,900 | Heavy winter snowpack buries young trees until late summer |
Swiss Alps | 47°N | 2,200 | 7,200 | [34] |
Mount Katahdin,Maine,United States | 46°N | 1,150 | 3,800 | |
Eastern Alps,Austria, Italy | 46°N | 1,750 | 5,700 | More exposure tocold Russian windsthan Western Alps |
Sikhote-Alin,Russia | 46°N | 1,600 | 5,200 | [35] |
Alps ofPiedmont,Northwestern Italy | 45°N | 2,100 | 6,900 | |
New Hampshire,United States | 44°N | 1,350 | 4,400 | [36]Some peaks have even lower treelines because of fire and subsequent loss of soil, such asGrand MonadnockandMount Chocorua. |
Wyoming,United States | 43°N | 3,000 | 9,800 | |
Caucasus Mountains | 42°N | 2,400 | 7,900 | [37] |
RilaandPirinMountains,Bulgaria | 42°N | 2,300 | 7,500 | Up to 2,600 m (8,500 ft) on favorable locations.Mountain Pineis the most common tree line species. |
PyreneesSpain, France,Andorra | 42°N | 2,300 | 7,500 | Mountain Pineis the tree line species |
Steens Mountain,Oregon,US | 42°N | 2,500 | 8,200 | |
Wasatch Mountains,Utah,United States | 40°N | 2,900 | 9,500 | Higher (nearly 11,000 feet or 3,400 metres in theUintas) |
Rocky Mountain NP,CO,United States | 40°N | 3,550 | 11,600 | [32]On warm southwest slopes |
3,250 | 10,700 | On northeast slopes | ||
Yosemite,CA,United States | 38°N | 3,200 | 10,500 | [38]West side ofSierra Nevada |
3,600 | 11,800 | [38]East side of Sierra Nevada | ||
Sierra Nevada,Spain | 37°N | 2,400 | 7,900 | Precipitation low in summer |
Japanese Alps | 36°N | 2,900 | 9,500 | |
Khumbu,Himalaya | 28°N | 4,200 | 13,800 | [32] |
Yushan,Taiwan | 23°N | 3,600 | 11,800 | [39]Strong winds and poor soil restrict further grow of trees. |
Hawaii,United States | 20°N | 3,000 | 9,800 | [32]Geographic isolation and no local tree species with high tolerance to cold temperatures. |
Pico de Orizaba,Mexico | 19°N | 4,000 | 13,100 | [34] |
Costa Rica | 9.5°N | 3,400 | 11,200 | |
Mount Kinabalu,Borneo | 6.1°N | 3,400 | 11,200 | [40] |
Mount Kilimanjaro,Tanzania | 3°S | 3,100 | 10,200 | [32]Upper limit of forest trees; woody ericaeous scrub grows up to 3900m |
New Guinea | 6°S | 3,850 | 12,600 | [32] |
Andes,Peru | 11°S | 3,900 | 12,800 | East side; on west side tree growth is restricted by dryness |
Andes,Bolivia | 18°S | 5,200 | 17,100 | Western Cordillera; highest treeline in the world on the slopes ofSajama Volcano(Polylepis tarapacana) |
4,100 | 13,500 | Eastern Cordillera; treeline is lower because of lower solar radiation (more humid climate) | ||
Sierra de Córdoba,Argentina | 31°S | 2,000 | 6,600 | Precipitation low abovetrade winds,also high exposure |
Australian Alps,New South Wales,Australia | 36°S | |||
1,800 | 5,900 | Despite the far inland location, summers are cool relative to the latitude, with occasional summer snow; and heavy springtime snowfalls are common[41] | ||
Andes,Laguna del Laja,Chile | 37°S | 1,600 | 5,200 | Temperature rather than precipitation restricts tree growth[42] |
Mount Taranaki,North Island,New Zealand | 39°S | 1,500 | 4,900 | Strong maritime influence serves to cool summer and restrict tree growth |
NortheastTasmania,Australia | 41°S | 1,200 | 3,900 | Although sheltered on theleewardside of the island, summers are still cool for the latitude. |
SouthwestTasmania,Australia | 43°S | 750 | 2,500 | Exposed to thewesterly storm track,summer is extraordinarily cool for the latitude, with frequent summer snow. Springtime receives an extreme amount of cold, heavy precipitation; winds are likewise extreme. |
Fiordland,South Island,New Zealand | 45°S | 950 | 3,100 | Very snowy springs, strong cold winds and cool summers with frequent summer snow restrict tree growth[citation needed] |
Lago Argentino,Argentina | 50°S | 1,000 | 3,300 | Nothofagus pumilio[43] |
Torres del Paine,Chile | 51°S | 950 | 3,100 | Strong influence from theSouthern Patagonian Ice Fieldserves to cool summer and restrict tree growth[44] |
Navarino Island,Chile | 55°S | 600 | 2,000 | Strong maritime influence serves to cool summer and restrict tree growth[44] |
Arctic tree lines
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/6/67/Canada_tree_line_map.png/220px-Canada_tree_line_map.png)
Like the alpine tree lines shown above, polar tree lines are heavily influenced by local variables such asaspectof slope and degree of shelter. In addition,permafrosthas a major impact on the ability of trees to place roots into the ground. When roots are too shallow, trees are susceptible towindthrowand erosion. Trees can often grow in rivervalleysat latitudes where they could not grow on a more exposed site. Maritime influences such asocean currentsalso play a major role in determining how far from the equator trees can grow as well as the warm summers experienced in extreme continental climates.[citation needed]In northern inlandScandinaviathere is substantial maritime influence on high parallels that keep winters relatively mild, but enough inland effect to have summers well above the threshold for the tree line. Here are some typical polar treelines:
Location | Approx. longitude | Approx. latitude of tree line | Notes |
---|---|---|---|
Norway | 24°E | 70°N | TheNorth Atlantic currentmakes Arctic climates in this region warmer than other coastal locations at comparable latitude. In particular the mildness of winters preventspermafrost. |
West Siberian Plain | 75°E | 66°N | |
Central Siberian Plateau | 102°E | 72°N | Extremecontinental climatemeans the summer is warm enough to allow tree growth at higher latitudes, extending to northernmost forests of the world at 72°28'N atAry-Mas(102° 15' E) in theNovaya Rivervalley, a tributary of theKhatanga Riverand the more northernLukunsky groveat 72°31'N, 105° 03' E east from Khatanga River. |
Russian Far East(KamchatkaandChukotka) | 160°E | 60°N | TheOyashio Currentand strong winds affect summer temperatures to prevent tree growth. TheAleutian Islandsare almost completely treeless. |
Alaska,United States | 152°W | 68°N | Trees grow north to the south-facing slopes of the Brooks Range. The mountains block cold air coming off of the Arctic Ocean. |
Northwest Territories,Canada | 132°W | 69°N | Reaches north of the Arctic Circle because of the continental nature of the climate and warmer summer temperatures. |
Nunavut | 95°W | 61°N | Influence of the very coldHudson Baymoves the treeline southwards. |
Labrador Peninsula | 72°W | 56°N | Very strong influence of the Labrador Current on summer temperatures as well as altitude effects (much of Labrador is a plateau). In parts ofLabrador,the treeline extends as far south as 53°N. Along the coast the northernmost trees are at 58°N inNapartok Bay. |
Greenland | 50°W | 64°N | Determined by experimental tree planting in the absence of native trees because of isolation from natural seed sources; a very few trees are surviving, but growing slowly, atSøndre Strømfjord,67°N. There is one natural forest in theQinngua Valley. |
Antarctic tree lines
[edit]Trees exist onTierra del Fuego(55°S) at the southern end of South America, but generally not onsubantarctic islandsand not in Antarctica. Therefore, there is no explicit Antarctic tree line.
Kerguelen Island(49°S),South Georgia(54°S), and other subantarctic islands are all so heavily wind-exposed and with a too-cold summer climate (tundra) that none have any indigenous tree species. TheFalkland Islands(51°S) summer temperature is near the limit, but the islands are also treeless, although some planted trees exist.
Antarctic Peninsulais the northernmost point in Antarctica (63°S) and has the mildest weather—it is located 1,080 kilometres (670 mi) fromCape HornonTierra del Fuego—yet no trees survive there; only a few mosses, lichens, and species of grass do so. In addition, no trees survive on any of the subantarctic islands near the peninsula.
![](https://upload.wikimedia.org/wikipedia/commons/thumb/d/d5/BeagleChannelGlacier.jpg/220px-BeagleChannelGlacier.jpg)
SouthernRataforests exist onEnderby IslandandAuckland Islands(both 50°S) and these grow up to an elevation of 370 metres (1,200 ft) in sheltered valleys. These trees seldom grow above 3 m (9.8 ft) in height and they get smaller as one gains altitude, so that by 180 m (600 ft) they are waist-high. These islands have only between 600 and 800 hours of sun annually.Campbell Island(52°S) further south is treeless, except for one stunted Spruce, probably planted in 1907.[45]The climate on these islands is not severe, but tree growth is limited by almost continual rain and wind. Summers are very cold with an average January temperature of 9 °C (48 °F). Winters are mild 5 °C (41 °F) but wet.Macquarie Island(Australia) is located at 54°S and has no vegetation beyond snow grass and alpine grasses and mosses.[citation needed]
See also
[edit]Trees portal
- Montane ecosystems
- Ecotone:a transition between two adjacent ecological communities
- Edge effects:the effect of contrasting environments on an ecosystem
- Massenerhebung effect
- Snow line
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Tree line, the elevation above which trees do not grow, is about 4,400 feet in the White Mountains, nearly 2,000 feet below the summit of Mt. Washington.
- ^"Georgia's natural resources and conservation"(PDF).geostat.ge(in Georgian). National Statistic Office of Georgia.Retrieved2023-04-13.
- ^abSchoenherr, Allan A. (1995).A Natural History of California.UC Press.ISBN978-0-520-06922-0.
- ^"Đài Loan mảnh đất tính thảm thực vật chi phân ranh giới cùng thực vật khu hệ chi phân khu"(PDF).Archived fromthe original(PDF)on 2014-11-29.
- ^"Mount Kinabalu National Park".ecologyasia.Ecology Asia. 4 September 2016.Retrieved6 September2016.
- ^"Alpine trees | ANU Research School of Biology".
- ^Lara, Antonio;Villalba, Ricardo;Wolodarsky-Franke, Alexia; Aravena, Juan Carlos; Luckman, Brian H.; Cuq, Emilio (2005)."Spatial and temporal variation in Nothofagus pumilio growth at tree line along its latitudinal range (35°40′–55° S) in the Chilean Andes"(PDF).Journal of Biogeography.32(5): 879–893.doi:10.1111/j.1365-2699.2005.01191.x.S2CID51845387.
- ^Sottile, Gonzalo D.; Echeverría, Marcos E.; Tonello, Marcela S.; Marcos, María A.; Bamonte, Florencia P.; Rayó, Cecilia; Mancini, María V. (2020)."Dinámica de la vegetación andina del lago Argentino (50° S, 72° O) desde el retiro de los glaciares (ca. 12.000 años cal AP)".Andean Geology(in Spanish).47(3): 599–627.doi:10.5027/andgeoV47n3-3303.hdl:11336/141218.
- ^abAravena, Juan C.; Lara, Antonio; Wolodarsky-Franke, Alexia;Villalba, Ricardo;Cuq, Emilio (2002)."Tree-ring growth patterns and temperature reconstruction from Nothofagus pumilio (Fagaceae) forests at the upper tree line of southern, Chilean Patagonia".Revista Chilena de Historia Natural.75(2).doi:10.4067/S0716-078X2002000200008.hdl:11336/40918.
- ^Morwood, Maddy (4 Sep 2022)."How the world's loneliest tree is helping scientists advance climate change research".Australian Broadcasting Company.
Further reading
[edit]- Arno, S.F.; Hammerly, R.P. (1984).Timberline. Mountain and Arctic Forest Frontiers.Seattle: The Mountaineers.ISBN978-0-89886-085-6.
- Beringer, Jason; Tapper, Nigel J.; McHugh, Ian; Chapin, F. S. III; et al. (2001)."Impact of Arctic treeline on synoptic climate".Geophysical Research Letters.28(22): 4247–4250.Bibcode:2001GeoRL..28.4247B.doi:10.1029/2001GL012914.
- Ødum, S (1979). "Actual and potential tree line in the North Atlantic region, especially in Greenland and the Faroes".Holarctic Ecology.2(4): 222–227.doi:10.1111/j.1600-0587.1979.tb01293.x.
- Ødum, S (1991). "Choice of species and origins for arboriculture in Greenland and the Faroe Islands".Dansk Dendrologisk Årsskrift.9:3–78.
- Singh, C.P.; Panigrahy, S.; Parihar, J.S.; Dharaiya, N. (2013)."Modeling environmental niche of Himalayan birch and remote sensing based vicarious validation"(PDF).Tropical Ecology.54(3): 321–329.
- Singh, C.P.; Panigrahy, S.; Thapliyal, A.; Kimothi, M.M.; Soni, P.; Parihar, J.S. (2012)."Monitoring the alpine treeline shift in parts of the Indian Himalayas using remote sensing"(PDF).Current Science.102(4): 559–562. Archived fromthe original(PDF)on 2013-05-16.
- Panigrahy, Sushma; Singh, C.P.; Kimothi, M.M.; Soni, P.; Parihar, J.S. (2010)."The Upward Migration of Alpine Vegetation as an Indicator of Climate Change: Observations from Indian Himalayan region using Remote Sensing Data"(PDF).NNRMS(B).35:73–80. Archived from the original on November 24, 2011.
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:CS1 maint: unfit URL (link) - Singh, C.P. (2008)."Alpine ecosystems in relation to climate change".ISG Newsletter.14:54–57.
- Ameztegui, A; Coll, L; Brotons, L; Ninot, JM (2016)."Land-use legacies rather than climate change are driving the recent upward shift of the mountain tree line in the Pyrenees"(PDF).Global Ecology and Biogeography.25(3): 263.doi:10.1111/geb.12407.hdl:10459.1/65151.