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tree line

{{Short description|Edge of the habitat at which trees are capable of growing}}

File:Tree line above St. Moritz.jpg. May 2009]]

File:Tree line.jpg

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 (usually low temperatures, extreme snowpack, or associated lack of available moisture).{{Cite book |last=Elliott-Fisk |first=D.L. |title=North American Terrestrial Vegetation |publisher=Cambridge University Press |year=2000 |isbn=978-0-521-55986-7 |editor-last=Barbour |editor-first=M.G. |edition=2nd |chapter=The Taiga and Boreal Forest |editor-last2=Billings |editor-first2=M.D.}}{{rp|51}} The tree line is sometimes distinguished from a lower timberline, which is the line below which trees form a forest with a closed canopy.{{Cite book |last=Jørgensen |first=S.E. |title=Ecosystem Ecology |publisher=Academic Press |year=2009 |isbn=978-0-444-53466-8}}{{rp|151}}{{Cite book |last=Körner |first=C. |title=Alpine Treelines: Functional Ecology of the Global High Elevation Tree Limits |publisher=Springer |others=Illustrated by S. Riedl |year=2012 |isbn=978-3-0348-0396-0}}{{rp|18}}

At the tree line, tree growth is often sparse, stunted, and deformed by wind and cold. This is sometimes known as {{lang|de|krummholz}} (German for "crooked wood").{{Cite book |last1=Zwinger |first1=A. |title=Land Above the Trees: A Guide to American Alpine Tundra |last2=Willard |first2=B.E. |publisher=Big Earth Publishing |year=1996 |isbn=978-1-55566-171-7}}{{rp|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.{{rp|55}} Given a certain latitude, the tree line is approximately 300 to 1000 meters below the permanent snow line and roughly parallel to it.{{Cite web |title=Why treelines? |url=https://www.geo.uzh.ch/microsite/alpecole/static/course/lessons/10/10c.htm}}

Causes

Due to their vertical structure, trees are more susceptible to cold than more ground-hugging forms of plants. Summer warmth generally sets the limit to which tree growth can occur: while tree line conifers are very frost-hardy during most of the year, they become sensitive to just 1 or 2 degrees of frost in mid-summer.{{Cite book |last=Tranquillini |first=W. |title=Physiological Ecology of the Alpine Timberline: tree existence at high altitudes with special reference to the European Alps |publisher=Springer-Verlag |year=1979 |isbn=978-3-642-67107-4 |location=New York, NY}}{{Cite book |last1=Coates |first1=K.D. |title=Ecology and silviculture of interior spruce in British Columbia |last2=Haeussler |first2=S. |last3=Lindeburgh |first3=S |last4=Pojar |first4=R. |last5=Stock |first5=A.J. |year=1994 |oclc=66824523}} 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 near Fairbanks, Alaska.{{Cite journal |last=Viereck |first=L.A. |year=1979 |title=Characteristics of treeline plant communities in Alaska |journal=Holarctic Ecology |volume=2 |issue=4 |pages=228–238 |doi=10.1111/j.1600-0587.1979.tb01294.x |jstor=3682417|bibcode=1979Ecogr...2..228V }}{{Cite book |last1=Viereck |first1=L.A. |title=Forest Ecosystems in the Alaskan Taiga |last2=Van Cleve |first2=K. |last3=Dyrness |first3=C. T. |publisher=Springer-Verlag |year=1986 |isbn=978-1-4612-4902-3 |editor-last=Van Cleve |editor-first=K. |location=New York, NY |pages=22–43 |chapter=Forest ecosystem distribution in the taiga environment |doi=10.1007/978-1-4612-4902-3_3 |editor-last2=Chapin |editor-first2=F.S. |editor-last3=Flanagan |editor-first3=P.W. |editor-last4=Viereck |editor-first4=L.A. |editor-last5=Dyrness |editor-first5=C.T.}} Survival depends on a sufficiency of new growth to support the tree. Wind can mechanically damage tree tissues directly, including blasting with windborne particles, and may also contribute to the desiccation of foliage, especially of shoots that project above the snow cover.{{cn|date=July 2023}}

The actual tree line is set by the mean temperature, while the realized tree line may be affected by disturbances, such as logging,{{Cite journal |last=Körner |first=Christian |date=November 1, 2021 |title=The cold range limit of trees |journal=Trends in Ecology & Evolution |volume=36 |issue=11 |pages=979–989 |doi=10.1016/j.tree.2021.06.011 |pmid=34272073 |bibcode=2021TEcoE..36..979K |s2cid=235999977}} or grazing{{cite journal |last1=Wang |first1=Xiaoyi |last2=Wang |first2=Tao|title=Enhanced habitat loss of the Himalayan endemic flora driven by warming-forced upslope tree expansion |journal=Nature Ecology & Evolution |date=2022 |volume=6 |issue=7|pages=890–899 |doi=10.1038/s41559-022-01774-3|pmid=35654898 |bibcode=2022NatEE...6..890W }} Most human activities cannot change the actual tree line, unless they affect the climate. The tree line follows the line where the seasonal mean temperature is approximately {{convert|6|C|F|disp=or}}.{{Cite journal |last1=Körner |first1=Christian |last2=Paulsen |first2=Jens |date=May 2004 |title=A World-Wide Study of High Altitude Treeline Temperatures |journal=J. Biogeogr. |volume=31 |pages=713–732 |doi=10.1111/j.1365-2699.2003.01043.x |jstor=3554841 |s2cid=59025355 |number=5|bibcode=2004JBiog..31..713K }} The seasonal mean temperature is taken over all days whose mean temperature is above {{convert|0.9|C|F}}. A growing season of 94 days above that temperature is required for tree growth.{{Cite journal |last1=Paulsen |first1=Jens |last2=Körner |first2=Christian |year=2014 |title=A climate-based model to predict potential treeline position around the globe |url=http://doc.rero.ch/record/324784/files/35_2014_Article_124.pdf |journal=Alpine Botany |volume=124 |issue=1 |pages=1–12 |doi=10.1007/s00035-014-0124-0 |bibcode=2014AlBot.124....1P |s2cid=8752987}}

Because of climate change, which leads to earlier snow melt and favorable conditions for tree establishment, the tree line in North Cascades National Park has risen more than {{convert|400|ft}} in 50 years.{{cite web |author= |title=Climate Change Resource Brief - North Cascades National Park |url=https://www.nps.gov/noca/learn/nature/climate-change-resource-brief.htm#:~:text=Forest%20line%20has%20moved%20up,pack%2C%20and%20earlier%20snow%20melt. |date=January 30, 2018 |website=U.S. National Park Service |language=en |access-date=May 13, 2025}}

Types

File:Distribution_of_Plants_in_a_Perpendicular_Direction_in_the_Torrid,_the_Temperate,_and_the_Rigid_Zones_1848_Alexander_Keith_Johnston.png, Tenerife, Himalaya, Alps, Pyrenees, and Lapland.]]

File:Bistrishko-Branishte.jpg and European spruce below the subalpine zone of Bistrishko Branishte, with the surmounting Golyam Rezen Peak, Vitosha Mountain, Sofia, Bulgaria]]

Several types of tree lines are defined in ecology and geography:

=Alpine=

File:Treeline In The Tararuas.JPG]]

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.{{rp|151}} The climate above the tree line of mountains is called an alpine climate,{{Cite book |last=Körner |first=C |title=Alpine plant life: functional plant ecology of high mountain ecosystems |publisher=Springer |year=2003 |isbn=978-3-540-00347-2}}{{rp|21}} and the habitat can be described as the alpine zone.{{Cite web |title=Alpine Tundra Ecosystem |url=https://www.nps.gov/romo/learn/nature/alpine_tundra_ecosystem.htm |access-date=2011-05-13 |website=Rocky Mountain National Park |publisher=National Park Service}} 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 the snowpack takes longer to melt. This shortens the growing season for trees.{{Cite book |last=Peet |first=R.K. |title=North American Terrestrial Vegetation |publisher=Cambridge University Press |year=2000 |isbn=978-0-521-55986-7 |editor-last=Barbour |editor-first=M.G. |edition=2nd |chapter=Forests and Meadows of the Rocky Mountains |editor-last2=Billings |editor-first2=M.D.}}{{rp|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 giant volcanoes in central Mexico, and on mountains in each of the 11 western states and throughout much of Canada and Alaska". 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 {{convert|3.5|F-change|C-change}} per {{convert|1000|ft|m}} of elevation gain in the dry mountains of the western United States, to {{convert|1.4|F-change|C-change}} per {{convert|1000|ft|m}} in the moister mountains of the eastern United States.{{Cite journal |last=Baker |first=F.S. |year=1944 |title=Mountain climates of the western United States |journal=Ecological Monographs |volume=14 |issue=2 |pages=223–254 |doi=10.2307/1943534 |jstor=1943534|bibcode=1944EcoM...14..223B }} Skin effects and topography can create microclimates that alter the general cooling trend.{{Cite book |last=Geiger |first=R. |url=https://archive.org/details/climatenearthegr032657mbp |title=The Climate near the Ground |publisher=Harvard University Press |year=1950 |location=Cambridge, MA}}

Compared with arctic tree lines, alpine tree lines may receive fewer than half of the number of degree days (above {{convert|10|C}}) 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.

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,{{Cite journal |last1=Sowell |first1=J.B. |last2=McNulty |first2=S.P. |last3=Schilling |first3=B.K. |year=1996 |title=The role of stem recharge in reducing the winter desiccation of Picea engelmannii (Pinaceae) needles at alpine timberline |journal=American Journal of Botany |volume=83 |issue=10 |pages=1351–1355 |doi=10.2307/2446122 |jstor=2446122}} and prolonging a supply of moisture through the early part of the growing season. However, snow accumulation in sheltered gullies in the Selkirk Mountains of southeastern British Columbia causes the tree line to be {{convert|400|m|ft}} lower than on exposed intervening shoulders.{{Cite journal |last=Shaw |first=C.H. |year=1909 |title=The causes of timberline on mountains: the role of snow |journal=Plant World |volume=12 |pages=169–181}}

In some mountainous areas, higher elevations above the condensation line, 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 {{convert|8000|ft|m|abbr=on}} is also above the condensation zone and results due to a lack of moisture.{{cn|date=July 2023}}

=Exposure=

On coasts and isolated mountains, the tree line is often much lower than in corresponding altitudes inland and in larger, more complex mountain systems, because strong winds reduce tree growth. In addition, the lack of suitable soil, such as along talus slopes or exposed rock formations, prevents trees from gaining an adequate foothold and exposes them to drought and sun.{{cn|date=September 2024}}

=Arctic=

File:Rivière aux Mélèzes 1.JPG

The Arctic tree line is the northernmost latitude in the Northern Hemisphere where trees can grow; farther north, it is too cold all year round to sustain trees.{{Cite book |last1=Pienitz |first1=Reinhard |title=Long-term environmental change in Arctic and Antarctic lakes |last2=Douglas |first2=Marianne S. V. |last3=Smol |first3=John P. |publisher=Springer |year=2004 |isbn=978-1-4020-2126-8 |page=102}} Extremely low temperatures, especially when prolonged, can freeze the internal sap of trees, killing them. In addition, permafrost in the soil can prevent trees from getting their roots deep enough for the necessary structural support.{{cn|date=July 2023}}

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 {{convert|145|km|mi}} and widening markedly from west to east,{{Cite journal |last1=Timoney |first1=K.P. |last2=La Roi |first2=G.H. |last3=Zoltai |first3=S.C. |last4=Robinson |first4=A.L. |year=1992 |title=The high subarctic forest–tundra of northwestern Canada: position, width, and vegetation gradients in relation to climate |journal=Arctic |volume=45 |issue=1 |pages=1–9 |doi=10.14430/arctic1367 |jstor=40511186 |doi-access=free}} in contrast with the telescoped alpine timberlines.{{Cite book |last=Arno |first=S.F. |title=Timberline: Mountain and Arctic Forest Frontiers |publisher=The Mountaineers |year=1984 |isbn=978-0-89886-085-6 |location=Seattle, WA}} North of the arctic tree line lies the low-growing tundra, and southwards lies the boreal forest.

Two zones can be distinguished in the Arctic tree line:{{Cite journal |last=Löve |first=Dd |year=1970 |title=Subarctic and subalpine: where and what? |journal=Arctic and Alpine Research |volume=2 |issue=1 |pages=63–73 |doi=10.2307/1550141 |jstor=1550141}}{{Cite journal |last1=Hare |first1=F. Kenneth |last2=Ritchie |first2=J.C. |year=1972 |title=The boreal bioclimates |journal=Geographical Review |volume=62 |issue=3 |pages=333–365 |doi=10.2307/213287 |jstor=213287|bibcode=1972GeoRv..62..333H }} a forest–tundra zone of scattered patches of krummholz or 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 of Cladonia spp. lichens. The proportion of trees to lichen mat increases southwards towards the "forest line", where trees cover 50 percent or more of the landscape.{{Cite journal |last1=R.A. |first1=Black |last2=Bliss |first2=L.C. |year=1978 |title=Recovery sequence of Picea mariana–Vaccinium uliginosum forests after burning near Inuvik, Northwest Territories, Canada |journal=Canadian Journal of Botany |volume=56 |issue=6 |pages=2020–2030 |doi=10.1139/b78-243|bibcode=1978CaJB...56.2020B }}

=Antarctic=

{{Further|Antipodes Subantarctic Islands tundra|Tierra del Fuego}}

A southern treeline exists in the New Zealand Subantarctic Islands and the Australian Macquarie Island, with places where mean annual temperatures above {{convert|5|C|F}} support trees and woody plants, and those below {{convert|5|C|F}} do not.{{WWF ecoregion|id=aa1101|name=Antipodes Subantarctic Islands tundra}}

Another treeline exists in the southwesternmost parts of the Magellanic subpolar forests ecoregion, where the forest merges into the subantarctic tundra (termed Magellanic moorland or Magellanic tundra).{{WWF ecoregion|id=nt0402|name=Magellanic subpolar Nothofagus forests}} For example, the northern halves of Hoste and Navarino Islands have Nothofagus antarctica forests but the southern parts consist of moorlands and tundra.

Tree species near tree line

File:Vihren Peak.jpg, Pirin Mountains, Bulgaria]]

File:Larix gmelinii0.jpg growing close to the Arctic tree line in the Kolyma region, Arctic northeast Siberia]]

File:Valle del Frances.jpg lenga forest close to the tree line in Torres del Paine National Park, Chile]]

Some typical Arctic and alpine tree line tree species (note the predominance of conifers):

=Australia=

=Eurasia=

{{div col|colwidth=33em}}

  • Dahurian larch (Larix gmelinii)
  • Macedonian pine (Pinus peuce)
  • Swiss pine (Pinus cembra)
  • Mountain pine (Pinus mugo)
  • Arctic white birch (Betula pubescens subsp. tortuosa)
  • Rowan{{Cite book |last=Chalupa |first=V. |title=High-Tech and Micropropagation II |publisher=Springer Berlin Heidelberg |year=1992 |isbn=978-3-642-76424-0 |editor-last=Bajaj |editor-first=Y.P.S. |series=Biotechnology in Agriculture and Forestry |volume=18 |pages=211–226 |chapter=Micropropagation of European Mountain Ash (Sorbus aucuparia L.) and Wild Service Tree [Sorbus torminalis (L.) Cr.] |doi=10.1007/978-3-642-76422-6_11}} (Sorbus aucuparia)

{{div col end}}

=North America=

{{div col|colwidth=33em}}

{{div col end}}

=South America=

{{div col|colwidth=33em}}

  • Antarctic beech (Nothofagus antarctica)
  • Lenga beech (Nothofagus pumilio){{Cite journal |last1=Fajardo |first1=A |last2=Piper |first2=FI |last3=Cavieres |first3=LA |year=2011 |title=Distinguishing local from global climate influences in the variation of carbon status with altitude in a tree line species |journal=Global Ecology and Biogeography |volume=20 |issue=2 |pages=307–318 |doi=10.1111/j.1466-8238.2010.00598.x |bibcode=2011GloEB..20..307F |hdl-access=free |hdl=10533/134794|url=http://americanae.aecid.es/americanae/es/registros/registro.do?tipoRegistro=MTD&idBib=3304268 }}
  • 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).{{Cite journal |last=Dickinson |first=Joshua C. |date=1969 |title=The Eucalypt in the Sierra of Southern Peru |journal=Annals of the Association of American Geographers |volume=59 |issue=2 |pages=294–307 |doi=10.1111/j.1467-8306.1969.tb00672.x |issn=0004-5608 |jstor=2561632}}

{{div col end}}

Worldwide distribution

=Alpine tree lines=

File:Treeline elevation.gif

The alpine tree line at a location is dependent on local variables, such as aspect of slope, rain shadow and proximity to either geographical pole. In addition, in some tropical or island localities, the lack of biogeographical access to species that have evolved in a subalpine environment can result in lower tree lines than one might expect by climate alone.{{cn|date=July 2023}}

Averaging over many locations and local microclimates, the treeline rises {{convert|75|m|ft|round=5}} when moving 1 degree south from 70 to 50°N, and {{convert|130|m|ft}} per degree from 50 to 30°N. Between 30°N and 20°S, the treeline is roughly constant, between {{convert|3500|and|4000|m|ft}}.

Here is a list of approximate tree lines from locations around the globe:

{{clear right}}

class="wikitable sortable"
style="text-align:left;" rowspan="2" class="unsortable"|Location

! style="text-align:left;" rowspan="2"|Approx. latitude

!colspan=2|Approx. elevation of tree line

!rowspan="2" class="unsortable"|Notes

style="text-align:center;"|(m)

! style="text-align:center;"|(ft)

Finnmarksvidda, Norway

|data-sort-value="69"|69°N

| {{convert|500|m|ft

2|disp=table}}

|At 71°N, near the coast, the tree-line is below sea level (Arctic tree line).

Abisko, Sweden

|data-sort-value="68"|68°N

| {{convert|650|m|ft

2|disp=table}}

|

Chugach Mountains, Alaska

|data-sort-value="61"|61°N

| {{convert|700|m|ft

2|disp=table}}

|Tree line around {{convert|1500|ft|m}} or lower in coastal areas

Southern Norway

|data-sort-value="61"|61°N

| {{convert|1100|m|ft

2|disp=table}}

|Much lower near the coast, down to {{convert|500|–|600|m|ft}}.

Scotland, United Kingdom

|data-sort-value="57"|57°N

| {{convert|500|m|ft

2|disp=table}}

|Strong maritime influence serves to cool summer and restrict tree growth{{Cite web |title=Action For Scotland's Biodiversity |url=http://www.scotland.gov.uk/Resource/Doc/314275/0099822.pdf}}{{rp|79}}

Northern Quebec

|data-sort-value="56"|56°N

| {{convert|0|m|ft

2|disp=table}}

| The cold Labrador Current originating in the arctic makes eastern Canada the sea-level region with the most southern tree-line in the northern hemisphere.

Southern Urals

|data-sort-value="55"|55°N

| {{convert|1100|m|ft

2|disp=table}}

|

Canadian Rockies

|data-sort-value="51"|51°N

| {{convert|2400|m|ft

2|disp=table}}

|

Tatra Mountains

|data-sort-value="49"|49°N

| {{convert|1600|m|ft

2|disp=table}}

|

Olympic Mountains, Washington, United States

|data-sort-value="47"|47°N

| {{convert|1500|m|ft

2|disp=table}}

|Heavy winter snowpack buries young trees until late summer

Swiss Alps

|data-sort-value="47"|47°N

| {{convert|2200|m|ft

2|disp=table}}

|

Mount Katahdin, Maine, United States

|data-sort-value="46"|46°N

| {{convert|1150|m|ft

2|disp=table}}

|

Eastern Alps, Austria, Italy

|data-sort-value="46"|46°N

| {{convert|1750|m|ft

2|disp=table}}

| More exposure to cold Russian winds than Western Alps

Sikhote-Alin, Russia

|data-sort-value="46"|46°N

| {{convert|1600|m|ft

2|disp=table}}

| {{Cite web |title=Physiogeography of the Russian Far East |url=http://geobotanica.ru/PH_GEO/phys.html}}

Alps of Piedmont, Northwestern Italy

|data-sort-value="45"|45°N

| {{convert|2100|m|ft

2|disp=table}}
New Hampshire, United States

|data-sort-value="44"|44°N

| {{convert|1350|m|ft

2|disp=table}}

| {{Cite web |title=Mount Washington State Park |url=http://www.nhstateparks.com/washington.html |archive-url=https://web.archive.org/web/20130403200610/http://nhstateparks.com/washington.html |archive-date=2013-04-03 |access-date=2013-08-22 |publisher=New Hampshire State Parks |quote=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.}} Some peaks have even lower treelines because of fire and subsequent loss of soil, such as Grand Monadnock and Mount Chocorua.

Wyoming, United States

|data-sort-value="43"|43°N

| {{convert|3000|m|ft

2|disp=table}}

|

Caucasus Mountains

|data-sort-value="42"|42°N

| {{convert|2400|m|ft

2|disp=table}}

| {{Cite web |title=Georgia's natural resources and conservation |url=https://www.geostat.ge/media/19691/saqarTvelos-bunebrivi-resursebi-da-garemos-dacva_2008.pdf |access-date=2023-04-13 |website=geostat.ge |publisher=National Statistic Office of Georgia |language=ka}}

Rila and Pirin Mountains, Bulgaria

|data-sort-value="42"|42°N

| {{convert|2300|m|ft

2|disp=table}}

| Up to {{convert|2600|m|ft|abbr=on}} on favorable locations. Mountain Pine is the most common tree line species.

Pyrenees Spain, France, Andorra

|data-sort-value="42"|42°N

| {{convert|2300|m|ft

2|disp=table}}

| Mountain Pine is the tree line species

Steens Mountain, Oregon, US

|data-sort-value="42"|42°N

|{{convert|2500|m|ft

2|disp=table}}
Wasatch Mountains, Utah, United States

|data-sort-value="40"|40°N

| {{convert|2900|m|ft

2|disp=table}}

|Higher (nearly {{convert|11,000|ft|m|disp=or}} in the Uintas)

rowspan="2" |Rocky Mountain NP, CO, United States

| rowspan="2" data-sort-value="40"|40°N

| {{convert|3550|m|ft

2|disp=table}}

| On warm southwest slopes

{{convert|3250|m|ft
2|disp=table}}

|On northeast slopes

rowspan="2" | Yosemite, CA, United States

| rowspan="2" data-sort-value="38"|38°N

| {{convert|3200|m|ft

2|disp=table}}

|{{Cite book |last=Schoenherr |first=Allan A. |title=A Natural History of California |title-link=A Natural History of California |publisher=UC Press |year=1995 |isbn=978-0-520-06922-0}} West side of Sierra Nevada

{{convert|3600|m|ft
2|disp=table}}

| East side of Sierra Nevada

Sierra Nevada, Spain

|data-sort-value="37"|37°N

| {{convert|2400|m|ft

2|disp=table}}

|Precipitation low in summer

Japanese Alps

|data-sort-value="36"|36°N

| {{convert|2900|m|ft

2|disp=table}}

|

Khumbu, Himalaya

|data-sort-value="28"|28°N

| {{convert|4200|m|ft

2|disp=table}}

|

Yushan, Taiwan

|data-sort-value="23"|23°N

|{{convert|3600|m|ft

2|disp=table}}

|{{Cite web |title=台灣地帶性植被之區劃與植物區系之分區 |url=http://conservation.forest.gov.tw/public/Data/5111513445271.PDF |archive-url=https://web.archive.org/web/20141129065554/http://conservation.forest.gov.tw/public/Data/5111513445271.PDF |archive-date=2014-11-29}} Strong winds and poor soil restrict further grow of trees.

Hawaii, United States

|data-sort-value="20"|20°N

| {{convert|3000|m|ft

2|disp=table}}

| Geographic isolation and no local tree species with high tolerance to cold temperatures.

Pico de Orizaba, Mexico

|data-sort-value="19"|19°N

| {{convert|4000|m|ft

2|disp=table}}

|{{Cite web |last=Körner |first=Ch |title=High Elevation Treeline Research |url=http://pages.unibas.ch/botschoen/treeline_elevation/index.shtml |archive-url=https://web.archive.org/web/20110927151628/http://pages.unibas.ch/botschoen/treeline_elevation/index.shtml |archive-date=2011-09-27 |access-date=2010-06-14}}

Costa Rica

|data-sort-value="9.5"|9.5°N

| {{convert|3400|m|ft

2|disp=table}}

|

Mount Kinabalu, Borneo

|data-sort-value="6.1"|6.1°N

| {{convert|3400|m|ft

2|disp=table}}

|{{Cite web |date=4 September 2016 |title=Mount Kinabalu National Park |url=http://www.ecologyasia.com/html-loc/mount-kinabalu.htm |access-date=6 September 2016 |website=www.ecologyasia.com |publisher=Ecology Asia}}

Mount Kilimanjaro, Tanzania

|data-sort-value="-3"|3°S

| {{convert|3100|m|ft

2|disp=table}}

|{{Cite journal |last=Körner |first=Ch |year=1998 |title=A re-assessment of high elevation treeline positions and their explanation |journal=Oecologia |volume=115 |issue=4 |pages=445–459 |bibcode=1998Oecol.115..445K |citeseerx=10.1.1.454.8501 |doi=10.1007/s004420050540 |pmid=28308263 |s2cid=8647814}} Upper limit of forest trees; woody ericaeous scrub grows up to 3900m

New Guinea

|data-sort-value="-6"|6°S

| {{convert|3850|m|ft

2|disp=table}}

|

Andes, Peru

|data-sort-value="-11"|11°S

| {{convert|3900|m|ft

2|disp=table}}

|East side; on west side tree growth is restricted by dryness

rowspan="2" |Andes, Bolivia

| rowspan="2" data-sort-value="-18" |18°S

| {{convert|5200|m|ft|disp=table}}

|Western Cordillera; highest treeline in the world on the slopes of Sajama Volcano (Polylepis tarapacana)

{{convert|4100|m|ft
2|disp=table}}

|Eastern Cordillera; treeline is lower because of lower solar radiation (more humid climate)

Sierra de Córdoba, Argentina

|data-sort-value="-31"|31°S

| {{convert|2000|m|ft

2|disp=table}}

|Precipitation low above trade winds, also high exposure

rowspan="2" |Australian Alps, New South Wales, Australia

| rowspan="2" data-sort-value="-36"|36°S

{{convert|1800|m|ft
2|disp=table}}

|Despite the far inland location, summers are cool relative to the latitude, with occasional summer snow; and heavy springtime snowfalls are common{{Cite web |title=Alpine trees | ANU Research School of Biology |url=https://biology.anu.edu.au/news-events/news/alpine-trees}}

Andes, Laguna del Laja, Chile

|data-sort-value="-37"|37°S

| {{convert|1600|m|ft

2|disp=table}}

|Temperature rather than precipitation restricts tree growth{{Cite journal |last1=Lara |first1=Antonio |last2=Villalba |first2=Ricardo |author-link2=Ricardo Villalba |last3=Wolodarsky-Franke |first3=Alexia |last4=Aravena |first4=Juan Carlos |last5=Luckman |first5=Brian H. |last6=Cuq |first6=Emilio |year=2005 |title=Spatial and temporal variation in Nothofagus pumilio growth at tree line along its latitudinal range (35°40′–55° S) in the Chilean Andes |url=http://www.osara.org/darwin_2009/articles/Lara%20et%20al%202005.pdf |journal=Journal of Biogeography |volume=32 |issue=5 |pages=879–893 |doi=10.1111/j.1365-2699.2005.01191.x |bibcode=2005JBiog..32..879L |s2cid=51845387}}

Mount Taranaki, North Island, New Zealand

|data-sort-value="-39"|39°S

| {{convert|1500|m|ft

2|disp=table}}

|Strong maritime influence serves to cool summer and restrict tree growth

Northeast Tasmania, Australia

| data-sort-value="-41" |41°S

| {{convert|1200|m|ft|disp=table}}

|Although sheltered on the leeward side of the island, summers are still cool for the latitude.

Southwest Tasmania, Australia

| data-sort-value="-43" |43°S

| {{convert|750|m|ft

2|disp=table}}

|Exposed to the westerly 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

|data-sort-value="-45"|45°S

| {{convert|950|m|ft

2|disp=table}}

|Very snowy springs, strong cold winds and cool summers with frequent summer snow restrict tree growth{{citation needed|date=July 2014}}

Lago Argentino, Argentina

|data-sort-value="-50"|50°S

| {{convert|1000|m|ft

2|disp=table}}

|Nothofagus pumilio{{Cite journal |last1=Sottile |first1=Gonzalo D. |last2=Echeverría |first2=Marcos E. |last3=Tonello |first3=Marcela S. |last4=Marcos |first4=María A. |last5=Bamonte |first5=Florencia P. |last6=Rayó |first6=Cecilia |last7=Mancini |first7=María V. |year=2020 |title=Dinámica de la vegetación andina del lago Argentino (50° S, 72° O) desde el retiro de los glaciares (ca. 12.000 años cal AP) |url=http://www.andeangeology.cl/index.php/revista1/article/view/V47n3-3303/html |journal=Andean Geology |language=es |volume=47 |issue=3 |pages=599–627 |doi=10.5027/andgeoV47n3-3303 |doi-access=free |bibcode=2020AndGe..47..599S |hdl-access=free |hdl=11336/141218}}

Torres del Paine, Chile

|data-sort-value="-51"|51°S

| {{convert|950|m|ft

2|disp=table}}

|Strong influence from the Southern Patagonian Ice Field serves to cool summer and restrict tree growth{{Cite journal |last1=Aravena |first1=Juan C. |last2=Lara |first2=Antonio |last3=Wolodarsky-Franke |first3=Alexia |last4=Villalba |first4=Ricardo |author-link4=Ricardo Villalba |last5=Cuq |first5=Emilio |year=2002 |title=Tree-ring growth patterns and temperature reconstruction from Nothofagus pumilio (Fagaceae) forests at the upper tree line of southern, Chilean Patagonia |journal=Revista Chilena de Historia Natural |volume=75 |issue=2 |doi=10.4067/S0716-078X2002000200008 |doi-access=free |hdl-access=free |hdl=11336/40918}}

Navarino Island, Chile

|data-sort-value="-55"|55°S

| {{convert|600|m|ft

2|disp=table}}

|Strong maritime influence serves to cool summer and restrict tree growth

=Arctic tree lines=

File:Canada tree line map.png

Like the alpine tree lines shown above, polar tree lines are heavily influenced by local variables such as aspect of slope and degree of shelter. In addition, permafrost has a major impact on the ability of trees to place roots into the ground. When roots are too shallow, trees are susceptible to windthrow and erosion. Trees can often grow in river valleys at latitudes where they could not grow on a more exposed site. Maritime influences such as ocean currents also 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.{{cn|date=July 2023}} In northern inland Scandinavia there 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:

{{Clear}}

class="wikitable sortable"
align="left" class="unsortable"|Location

!align="left"|Approx. longitude

!Approx. latitude of tree line

!class="unsortable"|Notes

Norway

|{{sort|024|24°E}}

| style="text-align:center;"|70°N

|The North Atlantic current makes Arctic climates in this region warmer than other coastal locations at comparable latitude. In particular the mildness of winters prevents permafrost.

West Siberian Plain

|{{sort|075|75°E}}

| style="text-align:center;"|66°N

|

Central Siberian Plateau

|{{sort|102|102°E}}

| style="text-align:center;"|72°N

|Extreme continental climate means the summer is warm enough to allow tree growth at higher latitudes, extending to northernmost forests of the world at 72°28'N at Ary-Mas (102° 15' E) in the Novaya River valley, a tributary of the Khatanga River and the more northern Lukunsky grove at 72°31'N, 105° 03' E east from Khatanga River.

Russian Far East (Kamchatka and Chukotka)

|{{sort|160|160°E}}

| style="text-align:center;"|60°N

|The Oyashio Current and strong winds affect summer temperatures to prevent tree growth. The Aleutian Islands are almost completely treeless.

Alaska, United States

|{{sort|208|152°W}}

| style="text-align:center;"|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

|{{sort|228|132°W}}

| style="text-align:center;"|69°N

|Reaches north of the Arctic Circle because of the continental nature of the climate and warmer summer temperatures.

Nunavut

|{{sort|265|95°W}}

| style="text-align:center;"|61°N

|Influence of the very cold Hudson Bay moves the treeline southwards.

Labrador Peninsula

|{{sort|293|72°W}}

| style="text-align:center;"|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 of Labrador, the treeline extends as far south as 53°N. Along the coast the northernmost trees are at 58°N in Napartok Bay.

Greenland

|{{sort|315|50°W}}

| style="text-align:center;"|69°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, at Søndre Strømfjord, 67°N. There is one natural forest in the Qinngua Valley.

=Antarctic tree lines=

Trees exist on Tierra del Fuego (55°S) at the southern end of South America, but generally not on subantarctic islands and not in Antarctica. Therefore, there is no explicit Antarctic tree line.{{cn|date=September 2024}}

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. The Falkland Islands (51°S) summer temperature is near the limit, but the islands are also treeless, although some planted trees exist.{{cn|date=September 2024}}

Antarctic Peninsula is the northernmost point in Antarctica (63°S) and has the mildest weather—it is located {{convert|1080|km|mi}} from Cape Horn on Tierra 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.{{cn|date=September 2024}}

File:BeagleChannelGlacier.jpg, 55°S.]]

Southern Rata forests exist on Enderby Island and Auckland Islands (both 50°S) and these grow up to an elevation of {{convert|1200|ft|m|order=flip}} in sheltered valleys. These trees seldom grow above {{convert|3|m|ft|abbr=on}} in height and they get smaller as one gains altitude, so that by {{convert|600|ft|m|abbr=on|order=flip}} 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.{{Cite news |last=Morwood |first=Maddy |date=4 Sep 2022 |title=How the world's loneliest tree is helping scientists advance climate change research |url=https://www.abc.net.au/news/2022-09-05/the-worlds-loneliest-tree-advance-climate-change-research/101247300 |publisher=Australian Broadcasting Company}} 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 {{convert|9|C|F|abbr=on}}. Winters are mild {{convert|5|C|F|abbr=on}} but wet. Macquarie Island (Australia) is located at 54°S and has no vegetation beyond snow grass and alpine grasses and mosses.{{Citation needed|date=October 2011}}

See also

References

{{Reflist|33em}}

Further reading

  • {{Cite book |last1=Arno |first1=S.F. |title=Timberline. Mountain and Arctic Forest Frontiers |last2=Hammerly |first2=R.P. |publisher=The Mountaineers |year=1984 |isbn=978-0-89886-085-6 |location=Seattle}}
  • {{Cite journal |last1=Beringer |first1=Jason |last2=Tapper |first2=Nigel J. |last3=McHugh |first3=Ian |last4=Chapin |first4=F. S. III |last5=Lynch |first5=Amanda H. |last6=Serreze |first6=Mark C. |last7=Slater |first7=Andrew |display-authors=4 |year=2001 |title=Impact of Arctic treeline on synoptic climate |journal=Geophysical Research Letters |volume=28 |issue=22 |pages=4247–4250 |bibcode=2001GeoRL..28.4247B |doi=10.1029/2001GL012914 |doi-access=free}}
  • {{Cite journal |last=Ødum |first=S |year=1979 |title=Actual and potential tree line in the North Atlantic region, especially in Greenland and the Faroes |journal=Holarctic Ecology |volume=2 |issue=4 |pages=222–227 |doi=10.1111/j.1600-0587.1979.tb01293.x|bibcode=1979Ecogr...2..222O }}
  • {{Cite journal |last=Ødum |first=S |year=1991 |title=Choice of species and origins for arboriculture in Greenland and the Faroe Islands |journal=Dansk Dendrologisk Årsskrift |volume=9 |pages=3–78}}
  • {{Cite journal |last1=Singh |first1=C.P. |last2=Panigrahy |first2=S. |last3=Parihar |first3=J.S. |last4=Dharaiya |first4=N. |year=2013 |title=Modeling environmental niche of Himalayan birch and remote sensing based vicarious validation |url=http://www.tropecol.com/pdf/open/PDF_54_3/05-Singh%20et%20al.pdf |archive-url=https://web.archive.org/web/20150721180634/http://www.tropecol.com/pdf/open/PDF_54_3/05-Singh%20et%20al.pdf |url-status=usurped |archive-date=July 21, 2015 |journal=Tropical Ecology |volume=54 |issue=3 |pages=321–329}}
  • {{Cite journal |last1=Singh |first1=C.P. |last2=Panigrahy |first2=S. |last3=Thapliyal |first3=A. |last4=Kimothi |first4=M.M. |last5=Soni |first5=P. |last6=Parihar |first6=J.S. |year=2012 |title=Monitoring the alpine treeline shift in parts of the Indian Himalayas using remote sensing |url=http://cs-test.ias.ac.in/cs/Volumes/102/04/0559.pdf |journal=Current Science |volume=102 |issue=4 |pages=559–562 |archive-url=https://web.archive.org/web/20130516014544/http://cs-test.ias.ac.in/cs/Volumes/102/04/0559.pdf |archive-date=2013-05-16}}
  • {{Cite journal |last1=Panigrahy |first1=Sushma |last2=Singh |first2=C.P. |last3=Kimothi |first3=M.M. |last4=Soni |first4=P. |last5=Parihar |first5=J.S. |year=2010 |title=The Upward Migration of Alpine Vegetation as an Indicator of Climate Change: Observations from Indian Himalayan region using Remote Sensing Data |url=http://isro.org/newsletters/contents/nnrms/NNRMS-Bulletin-2010.pdf |url-status=unfit |journal=NNRMS(B) |volume=35 |pages=73–80 |archive-url=https://web.archive.org/web/20111124014543/http://isro.org/newsletters/contents/nnrms/NNRMS-Bulletin-2010.pdf |archive-date=November 24, 2011}}
  • {{Cite journal |last=Singh |first=C.P. |year=2008 |title=Alpine ecosystems in relation to climate change |url=https://www.scribd.com/doc/13724806/Alpine-Climate |journal=ISG Newsletter |volume=14 |pages=54–57}}
  • {{Cite journal |last1=Ameztegui |first1=A |last2=Coll |first2=L |last3=Brotons |first3=L |last4=Ninot |first4=JM |year=2016 |title=Land-use legacies rather than climate change are driving the recent upward shift of the mountain tree line in the Pyrenees |url=http://arxiudigital.ctfc.cat/docs/upload/27_520_Ameztegui_et_al-Global_Ecology_and_Biogeography.pdf |journal=Global Ecology and Biogeography |volume=25 |issue=3 |page=263 |doi=10.1111/geb.12407 |bibcode=2016GloEB..25..263A |hdl-access=free |hdl=10459.1/65151}}

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