View source for Bristlecone pine

{{short description|Three species of pine trees native to the Western United States}}
{{other uses|Bristlecone (disambiguation)}}
{{Use mdy dates|date=March 2017}}
{{Automatic taxobox
 | name               = Bristlecone pine
 | taxon              = Pinus subsect. Balfourianae
 | display_parents    = 2
 | image              = Prometheus Wheeler.jpg
 | image_caption      = A Great Basin bristlecone pine grove
 | image2             = ConeBristles.jpg
 | image2_caption     = The eponymous bristles
 | subdivision_ranks  = Species
 | subdivision        = 
* ''[[Pinus aristata]]''
* ''[[Pinus longaeva]]''
* ''[[Pinus balfouriana]]''
}}

The term '''bristlecone pine''' covers three [[species]] of [[pine]] tree (family [[Pinaceae]], genus ''[[Pinus]]'', subsection ''Balfourianae''). All three species are long-lived and highly resilient to harsh weather and bad soils. One of the three species, ''Pinus longaeva'', is among the [[Oldest life|longest-lived life forms]] on Earth. The oldest of this species is more than 4,800 years old,<ref name="oldest">{{cite web|url=http://www.rmtrr.org/oldlist.htm|title=Oldlist|publisher=Rocky Mountain Tree Ring Research|access-date=January 8, 2013}}</ref> making it the oldest known individual of any species. Many scientists are curious as to why this tree is able to live so long. In one study, they discovered that ''Pinus longaeva'' has higher levels of telomerase activity, which further slows or prevents the attrition rate of telomeres.<ref>Flanary, B. E., & Kletetschka, G. (2006). Analysis of telomere length and telomerase activity in tree species of various lifespans, and with age in the bristlecone pine Pinus longaeva. ''Rejuvenation Research'', ''9''(1), 61–63.</ref> This potentially contributes to the extended life of the bristlecone pine.

Despite their potential age and low reproductive rate, bristlecone pines, particularly ''Pinus longaeva'', are usually a [[primary succession|first-succession]] species, tending to occupy new open ground.<ref name="FEIS">{{cite web|url=http://www.fs.fed.us/database/feis/plants/tree/pinlon/all.html|title=Pinus longaeva|last=Howard|first=JL|year=2004|work=Fire Effects Information System|publisher=USDA|access-date=December 2, 2008}}</ref> They generally compete poorly in less-than-harsh environments, making them hard to cultivate.<ref name="FEIS" /> In gardens, they succumb quickly to root rot.<ref>{{cite web|url=http://eol.org/pages/1034948/details|website=EOL|publisher=National Museum of Natural History|title=Great Basin Bristlecone Pine}}</ref> They do very well, however, where most other plants cannot even grow, such as in rocky [[Dolomite (mineral)|dolomitic]] soils in areas with virtually no rainfall.<ref name="FEIS" />

Bristlecone pines grow in scattered [[subalpine]] groves at high altitude in arid regions of the [[Western United States]]. Bristlecones, along with all related species in class Pinopsida, are [[conifer cone|cone-bearing]] [[seed plant]]s commonly known as [[conifer]]s; the name comes from the prickles on the female cones.<ref>{{cite web|url=https://www.nwf.org/Educational-Resources/Wildlife-Guide/Plants-and-Fungi/Great-Basin-Bristlecone-Pine|title=Great Basin Bristlecone Pine|publisher=National Wildlife Federation|access-date=2025-10-02}}</ref>

== Species and range ==
[[File:Gnarly Bristlecone Pine.jpg|thumb|Great Basin bristlecone pines in the [[Ancient Bristlecone Pine Forest]] of the [[White Mountains (California)|White Mountains, California]]]]
There are three closely related species of bristlecone pines:
* [[Pinus longaeva|Great Basin bristlecone pine]] (''Pinus longaeva'') in [[Utah]], [[Nevada]] and eastern [[California]]. The famous longest-lived species; often the term ''bristlecone pine'' refers to this tree in particular.
* [[Pinus aristata|Rocky Mountain bristlecone pine]] (''Pinus aristata'') in [[Colorado]], [[New Mexico]] and [[Arizona]]. The most populous species; capable of forming closed canopies. Dwarf forms of this pine are sometimes cultivated.<ref>{{cite web|url=https://landscapeplants.oregonstate.edu/plants/pinus-aristata|title=Pinus aristata|work=Landscape plants|publisher=Oregon State University|access-date=2025-10-02}}</ref>
* [[Pinus balfouriana|Foxtail pine]] (''Pinus balfouriana'') with two disjunct populations found in the [[Klamath Mountains]] (subspecies ''balfouriana'') and the southern [[Sierra Nevada (U.S.)|Sierra Nevada]]<ref name="Moore2008">{{cite book |last1=Moore|first1=Gerry|last2=Kershner|first2=Bruce|first3=Craig|last3=Tufts|first4=Daniel|last4=Mathews|first5=Gil|last5=Nelson|last6=Spellenberg|first6=Richard|last7=Thieret|first7=John W.|first8=Terry|last8=Purinton|last9=Block|first9=Andrew|display-authors=4 |title=National Wildlife Federation Field Guide to Trees of North America |publisher=Sterling |location=New York |year=2008 |page=83 |isbn=978-1-4027-3875-3}}</ref> (subspecies ''austrina''). A small outlying population was reported in southern Oregon, but was proven to have been misidentified.<ref>{{cite book |last=Kauffmann |first=Michael E. |year=2012 |title=Conifer Country |location=Kneeland, CA |publisher=Backcountry Press |isbn=978-0-578-09416-8 |oclc=798852130}}</ref> Forms the thickest groves of the three.

At least some of the three species can hybridize in cultivation, but the ranges of wild populations do not overlap. The [[Colorado River]] and [[Green River (Colorado River tributary)|Green River]] produce a {{convert|260|km|mi|-1|disp=flip|adj=on}} gap between the ranges of ''P. longaeva'' and ''P. aristata'' and the northern [[Owens Valley]] provides a {{convert|30|km|mi|-1|disp=flip|adj=on}} gap between the ranges of ''P. longaeva'' and ''P. balfouriana''.<ref name="USFS">{{cite web |url=http://www.fs.fed.us/database/feis/plants/tree/pinlon/all.html |last=Fryer |first=Janet L |year=2004 |title=Pinus longaeva |publisher=U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory }}</ref>

== Description ==
Bristlecone pines grow in isolated groves just below the [[tree line]], between {{convert|6500|and|11000|ft|m}} elevation<ref>{{cite web|url=https://www.nps.gov/brca/learn/nature/bristleconepine.htm|title=Bristlecone Pines|publisher=US National Park Service|access-date=2025-10-03}}</ref> on dolomitic soils.<ref>{{cite web|url=https://sierraforever.org/ancient-bristlecone-pine-forest/|title=Ancient Bristlecone Pine Forest|publisher=Sierra Forever|access-date=2025-10-03}}</ref> The trees grow in soils that are shallow lithosols, usually derived from [[Dolomite (rock)|dolomite]] and sometimes limestone, and occasionally sandstone or quartzite soils. Dolomitic soils are alkaline, high in [[calcium]] and [[magnesium]], and low in [[phosphorus]]. Those factors tend to exclude other plant species, allowing bristlecones to thrive.<ref>{{cite journal|last1=Coop|first1=JD|last2=Schoettle|first2=AW|year=2009|title=Regeneration of rocky mountain bristlecone pine (pinus aristata) and limber pine (pinus flexilis) three decades after stand-replacing fires|journal=Forest Ecology and Management|volume=257|issue=3|pages=893–903|doi=10.1016/j.foreco.2008.10.034|bibcode=2009ForEM.257..893C |url=https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=23363&content=PDF|url-access=subscription}}{{dead link|date=June 2025|bot=medic}}{{cbignore|bot=medic}}</ref> Because of cold temperatures, dry soils, high winds, and short growing seasons, the trees grow very slowly. Even the tree's needles, which grow in bunches of five, can remain on the tree for forty years, which gives the tree's terminal branches the unique appearance of a long bottle brush.

The bristlecone pine's root system is mostly composed of highly branched, shallow roots, while a few large, branching roots provide structural support. The bristlecone pine is extremely drought tolerant due to its branched shallow root system, its waxy needles, and thick needle cuticles that aid in water retention.<ref name="USFS" />

[[File:Utah, Cedar Breaks National Monument, Great Basin Bristlecone Pine, bark.jpg|thumb|left|Gnarled bristlecone pine wood]]
The wood is very dense and resinous, and thus resistant to invasion by insects, fungi, and other potential pests. The tree's longevity is due in part to the wood's extreme durability. While other species of trees that grow nearby suffer rot, bare bristlecone pines can endure, even after death, often still standing on their roots, for many centuries. Exposed wood on living and dead trees does not rot, but rather erodes like stone due to wind, rain, and freezing, which creates unusual forms and shapes.

The bristlecone pine has an intrinsically low rate of reproduction and regeneration, and it is thought that under present climatic and environmental conditions the rate of regeneration may be insufficient to sustain its population.<ref name="IUCN">{{Cite iucn | author = Stritch, L. | author2 = Mahalovich, M. | author3 = Nelson, K.G. | name-list-style = amp | title = ''Pinus longaeva'' | volume = 2011 | article-number = e.T34024A9830878 | date = 2011 | doi = 10.2305/IUCN.UK.2011-2.RLTS.T34024A9830878.en | access-date = 10 January 2020}}</ref> The species are on the [[International Union for Conservation of Nature]] (IUCN) red list.<ref name="IUCN" /> The species are labeled under Least Concern (LC), the justification for this being that no subpopulations for Great Basin bristlecone pines are decreasing. Subpopulations seem to be increasing or remaining stable.<ref name="IUCN" /> Many bristlecone pine habitats have been protected, including the [[Inyo National Forest]]'s Ancient Bristlecone Pine Forest in the White Mountains of California and the [[Great Basin National Park]] in Nevada,<ref name="Global">{{cite web|url=http://www.globaltrees.org/|title=Global Trees Campaign|date=March 2008|access-date=July 30, 2011}}</ref><ref name="Sonic" /> where cutting or gathering wood is prohibited.<ref name="Global" />

[[File:A543, Bryce Canyon National Park, Utah, USA, bristlecone pine cones, 2016.jpg|thumb|Needles and cones]]
The green pine needles give the twisted branches a bottle-brush appearance. The needles of the tree surround the branch to an extent of about one foot near the tip of the limb.<ref name="NPS">{{cite web|publisher=U.S. National Park Service|title=Bristlecone pines|url=https://www.nps.gov/grba/planyourvisit/identifying-bristlecone-pines.htm}}</ref> The name bristlecone pine refers to the dark purple female cones that bear incurved prickles on their surface.<ref name="Sonic">{{cite web|url=http://www.sonic.net/bristlecone/home.html|title=The Ancient Bristlecone Pine|date=August 2003|access-date=July 30, 2011}}</ref> The dark color of these cones helps to absorb heat. After maturity, which takes about two years, the cones will become brown in color.<ref name="NPS" /> These ancient trees have a gnarled and stunted appearance, especially those found at high altitudes,<ref name="USFS" /> and have reddish-brown bark with deep fissures.<ref name="Conifers">{{cite web|url=http://www.conifers.org/|title=The Gymnosperm Database|date=March 2008|access-date=July 30, 2011}}</ref> As the tree ages, much of its [[vascular cambium]] layer may die. In very old specimens, often only a narrow strip of living tissue connects the roots to a handful of live branches. Even though the trees' needles may age, they still remain functional in regulating water and by their ability to photosynthesize.<ref name="USFS" />
{{clear left}}

== Oldest living organisms ==
[[File:Bristlecone Wheeler.jpg|thumb|left|This standing tree may have died hundreds of years ago. Scientific matching of dead trees' [[Dendrochronology#Growth rings|growth rings]] with living ones has created a 9,000-year-long record.]]
Bristlecone pines are known for attaining great ages. The oldest bristlecone pine in the White Mountains is [[Methuselah (pine tree)|Methuselah]], which has a verified age of {{Age nts|-2832|8|5}} years. It is located in the [[White Mountains (California)|White Mountains]] of [[Inyo County]] in Eastern California. However, the specific location of Methuselah is a closely guarded secret.<ref>{{cite news|url=https://www.nytimes.com/2003/06/17/science/at-age-4600-plus-methuselah-pine-tree-begets-new-offspring.html|title=At Age 4,600-Plus, Methuselah Pine Tree Begets New Offspring|first=Gwen|last=Kinkead|date=June 17, 2003|newspaper=New York Times}}</ref>

The other two species, ''Pinus balfouriana'' and ''Pinus aristata'', are also long-lived, though not to the extreme extent of ''P. longaeva''; specimens of both have been measured or estimated to be up to 3,000 years old.<ref name="pbs">{{cite web|url=https://www.pbs.org/wgbh/nova/methuselah/explore.html|title=Explore the Methuselah Grove|work=NOVA Online: Methuselah Tree|publisher=PBS|last=Bain|first=G. Donald|year=2001}}</ref> The longevity of the trees is believed to be related to the proportion of dead wood to live wood. This high ratio reduces respiration and water loss, thereby extending the life of the tree.<ref name="IUCN" />

Trees that reproduce by [[cloning]] can be considered to be much older than bristlecone pines. A colony of 47,000 [[Populus tremuloides|quaking aspen]] trees (nicknamed "[[Pando (tree)|Pando]]"), covering {{convert|106|acre}} in the [[Fishlake National Forest]] in [[Utah]], United States, has been estimated to be 80,000 years old, although [[Dendrochronology#Growth rings|tree ring]] samples date individual, above-ground trees at an average of about 130 years.<ref name="discovery">{{cite web |url=http://discovermagazine.com/1993/oct/thetremblinggian285 |title=''The Trembling Giant'' |access-date=May 8, 2008 |publisher=Discover Magazine |date=October 1, 1993 |author=Grant, Michael C. }}</ref><ref>{{cite web |url=https://www.nps.gov/brca/learn/nature/quakingaspen.htm |title=''Quaking Aspen'' |access-date=May 7, 2008 |publisher=[[National Park Service]] – [[Bryce Canyon]] }}</ref>

Bristlecone pines are invaluable to [[Dendroclimatology|dendroclimatologists]], because they provide the longest continual climatically sensitive tree-ring chronologies on Earth. By cross-dating millennia-old bristlecone pine debris, some chronologies reach beyond 9,000 years before present.<ref name="USFS" /> In addition, [[Isotope analysis|ratios of stable carbon isotopes]] from bristlecone pine tree rings are sensitive to past variations in moisture availability. This information can be used to reconstruct precipitation changes in the past.<ref>{{cite journal|last1=Bale|first1=RJ|last2=Robertson|first2=I|last3=Salzer|first3=MW|last4=Loader|first4=NJ|last5=Leavitt|first5=SW|last6=Gagen|first6=M|display-authors=4|year=2011|title=An annually resolved bristlecone pine carbon isotope chronology for the last millennium|journal=Quaternary Research|volume=76|issue=1|pages=22–29|doi=10.1016/j.yqres.2011.05.004|bibcode=2011QuRes..76...22B|s2cid=140565055}}</ref>

The Rocky Mountain population is severely threatened by an introduced fungal disease known as [[Cronartium ribicola|white pine blister rust]], and by [[mountain pine beetle]]s.<ref>{{cite news |url=https://www.nytimes.com/2010/09/28/science/28pines.html |work=The New York Times |first=Jim |last=Robbins |title=Old Trees May Soon Meet Their Match |date=September 27, 2010}}</ref> Climate change may also affect the species as temperatures increased {{convert|0.5–1|C-change}} over a 30-year period throughout the southern Rocky Mountain range. These changes in climate would mostly affect trees in higher elevations. With these problems, the genetic diversity within the species has become a concern;<ref>{{cite journal|last1=Schoettle|first1=AW|last2=Goodrich|first2=BA|last3=Hipkins|first3=V|last4=Richards|first4=C|last5=Kray|first5=J|year=2012|title=Geographic patterns of genetic variation and population structure in pinus aristata, rocky mountain bristlecone pine|journal=Canadian Journal of Forest Research|volume=42|issue=1|pages=23–37|doi=10.1139/x11-152 |bibcode=2012CaJFR..42...23S }}</ref> old specimens of bristlecone pine, however, have survived previous warmer periods.

== See also ==
* [[List of longest-living organisms]]

== References ==
{{Reflist}}

== Further reading ==
{{refbegin}}
* {{cite journal|last=Bailey|first=D.K.|year=1970|title=Phytogeography and taxonomy of Pinus subsection Balfourianae|journal=Ann. Missouri Bot. Gard.|volume=57|issue=2|pages=210–249|doi=10.2307/2395110|jstor=2395110 |bibcode=1970AnMBG..57..210B }}
* {{cite book|editor-last=Richardson|editor-first=D.M.|year=1998|title=Ecology and Biogeography of Pinus|publisher=Cambridge University Press|location=Cambridge|isbn=0-521-55176-5}}
{{refend}}

== External links ==
{{sister project links|auto=1}}
* [http://www.conifers.org/ Gymnosperm Database] – [http://www.conifers.org/pi/Pinus_longaeva.php ''Pinus longaeva''], [http://www.conifers.org/pi/Pinus_aristata.php ''Pinus aristata''], [http://www.conifers.org/pi/Pinus_balfouriana.php ''Pinus balfouriana'']
* [http://www.sonic.net/bristlecone/Martyr.html Prometheus: The Martyred One]

{{Taxonbar|from=Q515556}}

[[Category:Flora of Arizona|Pinus]]
[[Category:Flora of California|Pinus]]
[[Category:Flora of Colorado|Pinus]]
[[Category:Flora of Nevada|Pinus]]
[[Category:Flora of New Mexico|Pinus]]
[[Category:Flora of Utah|Pinus]]
[[Category:Pinus|Balfourianae]]
[[Category:Pinus taxa by common names]]
[[Category:Plant subsections]]
[[Category:Trees of Northern America|Pine, Bristlecone]]
[[Category:Flora without expected TNC conservation status]]