Syn: P. aristata Engelmann var. longaeva (D.K. Bailey) Little (Kral 1993).
Trees to 16 m tall and 200 cm dbh. Crown rounded or irregular; sometimes forms a krummholz at the alpine timberline. Bark red-brown, fissured with thick, scaly, irregular, blocky ridges. Branches contorted, pendent; twigs pale red-brown, aging gray to yellow-gray, puberulent, young branches resembling long bottlebrushes because of persistent leaves, closely spaced needle whorls, and uniform needle insertion angles. Buds ovoid-acuminate, pale red-brown, ca. 1 cm long, resinous. Leaves mostly 5 per fascicle, upcurved, persisting 10-43 years (among the longest persistence times known), 15-35 × 0.8-1.2 mm, deep yellow-green, with few resin splotches but often scurfy with pale scales. Abaxial surface lacks median groove but has 2 subepidermal resin bands. Adaxial surface is conspicuously whitened with stomata. Margins are entire or remotely and finely serrulate distally, apex bluntly acute to short-acuminate; sheath ca. 1 cm, soon forming rosette, shed early. Pollen cones cylindro-ellipsoid, 7-10 mm long, purple-red. Seed cones mature in 2 years, shedding seeds and falling soon thereafter, spreading, symmetric, lance-cylindric with rounded base before opening, lance-cylindric to narrowly ovoid when open, 6-9.5 cm long, purple, aging red-brown, nearly sessile; apophyses much thickened, sharply keeled; umbo central, raised on low buttress, truncate to umbilicate, abruptly narrowed to slender but stiff, variable prickle 1-6 mm, resin exudate pale. Seeds ellipsoid-obovoid; body 5-8 mm, pale brown, mottled with dark red; wing 10-12 mm (Kral 1993, R.M. Lanner e-mail 1999.12.20).
US: California, Nevada & Utah. Subalpine and at the upper (rarely, lower) treeline; elevations 1700-3400 m (Kral 1993). Also see Thompson et al. (1999). Hardy to Zone 4 (cold hardiness limit between -34.3°C and -28.9°C) (Bannister and Neuner 2001).
In many sites it shows a distinct preference for carbonate (limestone, dolomite or marble) substrates. In the White Mountains of California, for instance, the limit of the bristlecone grove coincides with a dolomite/sandstone contact. Bristlecones grow at remarkably high elevations. For example, on Wheeler Peak, Nevada, there are four timberlines - a lower timberline set by the heat and aridity of the valley floor desert, and above that, a timberline set by cold that defines the upper limits of piñon pine (Pinus monophylla) and juniper (Juniperus osteosperma). Still higher, there is a lower timberline of bristlecone pine defined by its tolerance of heat and drought, and above that is a final timberline beyond which winter's cold prevents even bristlecone from growing.
On the northeast ridge of Mount Charleston in the Spring Mountains outside of Las Vegas, Nevada, grows a single-trunked tree 368 cm dbh and 15.8 m tall (Robert Van Pelt e-mail 2004.02.04).
The oldest known living specimen is an unnamed tree, its location kept secret, but somewhere in the White Mountains of California. The tree was sampled by Schulman in the 1950s but its great age, 5,060 years, was not determined until laboratory work (counting and crossdating) was completed by Tom Harlan in 2012 (Brown 2013). The tree is quite healthy; the stated age corresponds to the growing season of 2012.
Until 2012, the oldest known tree was "Methuselah" tree, 4,789 years, age verified by crossdating, also sampled by Schulman with results worked up by Harlan. I'm not sure when that age was determined, but Schulman found the tree in 1957 and he died in 1958, so it seems likely the tree had 4,789 rings (crossdated) in the summer of 1957, in which case the tree was 4,832 years old in 2000. In 2013, it is 4,845 and still going.
An age of 4,844 years was determined post-mortem (after being cut down) for specimen WPM-114 from Wheeler Peak, NV. The age is largely crossdated (Brown 1996). The fact that this tree was cut down caused, as might be imagined, quite a scandal. The story can be found recounted, from different points of view, at several sites on the Internet.
Bristlecones share with a few other ancient pines the ability to adopt a strip-bark morphology. In strip-bark trees, the bark has died back from most of the tree's circumference, leaving a strip of living cambium (and bark) that usually runs up the protected leeward side of the trunk. The exposed dead wood then takes the brunt of windblown ice crystals and sand. These gradually wear away the exposed wood, and in time the tree rings that recorded the tree's youth may be entirely worn away by this process (Valmore C. LaMarche, 1985, pers. comm.). Some researchers believe the strip-bark habit is one adaptation that has allowed the bristlecones to reach such great age; by restricting their growth to a narrow strip of living tissue, they can produce a thicker annual ring in response to a given increment of annual net productivity, and thus maintain a thicker and healthier layer of cambium and sapwood.
Pinus longaeva is generally regarded as the longest-lived of all sexually reproducing, nonclonal species, with many individuals known to have ages exceeding 4,000 years. Due to the resinous wood and extremely cold and arid habitat, decay of dead wood is extremely slow, and wood on the ground in some stands has ages exceeding 10,000 years. This has permitted building a continuous chronology from the present back to 6828 BC (Hughes and Graumlich 1996). This record has been used, among other things, to calibrate the radiocarbon timescale (the rate of radiocarbon production in the atmosphere is not constant over time, thus the need for calibration). The species has been widely used in dendroclimatic reconstruction, most famously figuring in the popular debate over anthropogenic global warming, and in several classic studies of timberline ecology.
It is appropriate to note here that several of history's most noteworthy dendrochronologists have spent a large part of their lives studying this, the oldest and perhaps the hardiest of all the world's trees, in its remote mountain habitat. Edmund Schulman (1909-1958) is generally credited as the first person to discover the trees' great age, certainly the first to study the phenomenon. C. Wesley Ferguson worked closely with geochronologists to use ancient bristlecone wood to develop the radiocarbon timescale calibration. He also discovered and sampled many stands of very old trees (Ferguson 1969). Hal Fritts (1969) studied the relationship between bristlecone pine ring widths and climate variation. Valmore C. LaMarche (1969) did pioneering work studying how bristlecones survive in an extraordinarily high, dry, cold environment, and went on to use the tree-ring record from bristlecones to provide estimates of climatic change over the past several thousand years (LaMarche and Mooney 1967, 1972; LaMarche 1973, 1978). Donald A. Graybill was a pioneer in research efforts to discover evidence of global warming in the bristlecone pine record (LaMarche et al. 1984). He also assembled a very extensive collection of bristlecone tree-ring data. The close association between bristlecones and dendrochronologists (a mutualism, we might say) has been touched on by a number of authors, notable Cohen (1998).
Anyone desiring to learn more about this extraordinary tree would do well to read the work of these scientists. A bibliography of that work is available at the Bibliography of Dendrochronology; also look at the "See Also" section below.
The best-known place to see bristlecones is in the Inyo National Forest of California, where the U.S. Forest Service maintains an interpretive trail through an exceptional bristlecone grove (with a web site). In Great Basin National Park (Nevada), the National Park Service provides similar facilities, albeit in a much less remarkable grove. Other popular locations to see the trees include Bryce Canyon National Park (Utah) and Cedar Breaks National Monument (Utah), which again are not among the finer groves in terms of size or tree age. More memorable sights can be had for a little more effort on the ridges around Charleston Peak, outside Las Vegas, Nevada; a Google search will turn up a variety of sites providing information on these trails. I can also recommend the grove on the slopes of Duckwater Mountain in the White Pine Mountains of central-eastern Nevada, shown in some of the photos at left; however it will take some stamina and probably a high-clearance vehicle to get there. A more accessible and also very memorable grove is on the summit ridge of Cave Mountain, southeast of Ely, Nevada. A steep road passable for light trucks and sturdy sedans climbs to a communications complex on the summit of this peak and affords access to spectacular groves of ancient bristlecone and limber (Pinus flexilis) pines, as well as much younger trees, including a closed-canopy forest containing young bristlecone pine and white fire (Abies concolor). Such ecological diversity cannot be found at the popular groves mentioned above.
A wealth of information on this species is available at the Bristlecone Pine Home Page Among other things, it provides a description of the incident that culminated with cutting down the oldest living tree ever found.
White pine blister rust (Cronartium ribicola), an introduced fungal disease, has afflicted this and certain other white pines.
This species is one of the primary hosts for the dwarf mistletoe Arceuthobium cyanocarpum (Hawksworth and Wiens 1996).
Brown, Peter. 2013. Rocky Mountain Tree-Ring Research, OLDLIST. http://www.rmtrr.org/OLDLIST.htm, accessed 2013.03.15.
Cohen, Michael P. 1998. A garden of bristlecones. Reno, NV: University of Nevada Press.
Ferguson, C.W. 1969. A 7104-year annual tree-ring chronology for bristlecone pine, Pinus aristata, from the White Mountains, California. Tree-Ring Bulletin 29(3-4):3-29. Available online at www.treeringsociety.org/TRBTRR/TRBvol29_3-4_3-29.pdf (accessed 2006.06.05).
Fritts, Harold C. 1969. Bristlecone pine in the White Mountains of California, growth and ring-width characteristics. Papers of the Laboratory of Tree-Ring Research No.4. Tucson: University of Arizona Press.
Hughes, M. K. and L. J. Graumlich. 1996. Climatic variations and forcing mechanisms of the last 2000 years. Volume 141. Multi-millenial dendroclimatic studies from the western United States. NATO ASI Series, 109-124.
LaMarche Jr., Valmore C. and Harold A. Mooney. 1967. Altithermal timberline advance in western United States. Nature 213:980-982.
LaMarche Jr., Valmore C. 1969. Environment in relation to age of bristlecone pines. Ecology 50(1):53-59.
LaMarche Jr., Valmore C. and Harold A. Mooney. 1972. Recent climatic change and development of the bristlecone pine (Pinus longaeva Bailey) krummholz zone, Mt. Washington, Nevada. Arctic and Alpine Research 4(1):61-72.
LaMarche Jr., Valmore C. 1973. Holocene climatic variations inferred from tree line fluctuations in the White Mountains, California. Quaternary Research 3:632-660.
LaMarche Jr., Valmore C. 1978. Tree-ring evidence of past climatic variability. Nature 276:334-338.
LaMarche Jr., Valmore C., D. A. Graybill, Harold C. Fritts, and Martin R. Rose. 1984. Increasing atmospheric carbon dioxide: tree-ring evidence for growth enhancement in natural vegetation. Science 225:1019-1021.
Anonymous. 1958. Edmund Schulman: 1908-1958 (Obituary). Tree-Ring Bulletin 22:2-6. Available online at www.treeringsociety.org/TRBTRR/TRBvol22_2-6.pdf (accessed 2006.06.05).
Anonymous. 1988. Valmore C. LaMarche, Jr., 1937-1988 (obituary). Tree-Ring Bulletin 48:1. Available online at www.treeringsociety.org/TRBTRR/TRBvol48.pdf (accessed 2006.06.05).
HERE is a nice satellite photo of the Schulman grove in the White Mountains (2006.04.19).
Beasley, R.S. and J. O. Klemmedson. 1980. Ecological relationships of bristlecone pine. American Midland Naturalist 104(2):242-252.
Connor, Kristina F. and Ronald M. Lanner. 1987. The architectural significance of interfoliar branches in Pinus subsection Balfourianae. Canadian Journal of Forest Research 17(3):269-272.
Connor, Kristina F. and Ronald M. Lanner. 1991. Effects of tree age on pollen, seed, and seedling characteristics in Great Basin bristlecone pine. Botanical Gazette 152(1):107-113.
Critchfield, William B. 1977. Hybridization of foxtail and bristlecone pines. Madroño 24(4):193-212.
Hiebert, Ronald D. and J. L. Hamrick. 1984. An ecological study of bristlecone pine (Pinus longaeva) in Utah and eastern Nevada. Great Basin Naturalist 44(3):487-494.
Hiebert, Ronald D. and J. L. Hamrick. 1983. Patterns and levels of genetic variation in Great Basin bristlecone pine, Pinus longaeva. Evolution 37(2):302-310.
LaMarche Jr., Valmore C. 1963. Origin and geologic significance of buttress roots of bristlecone pines, White Mountains, California. Washington D.C.: U.S. Geological Survey Professional Paper 405-C.
LaMarche Jr., Valmore C. 1968. Rates of slope degradation as determined from botanical evidence, White Mountains, California. Washington D.C.: U.S. Geological Survey Professional Paper 352-I.
LaMarche Jr., Valmore C. and T. P. Harlan. 1973. Accuracy of tree ring dating of bristlecone pine for calibration of the radiocarbon time scale. Journal of Geophysical Research 78:8849-8858.
LaMarche Jr., Valmore C. and Charles W. Stockton. 1974. Chronologies from temperature-sensitive bristlecone pines at upper treeline in western United States. Tree-Ring Bulletin 34:21-45. Available online at www.treeringsociety.org/TRBTRR/TRBvol34_21-45.pdf (accessed 2006.06.05).
Lanner, Ronald M. 1988. Dependence of Great Basin bristlecone pine on Clark's nutcracker for regeneration at high elevations. Arctic and Alpine Research 20(3):358-362.
Mathiasen, Robert L. and Frank G. Hawksworth. 1980. Taxonomy and effects of dwarf mistletoe on bristlecone pine on the San Francisco Peaks, Arizona. Research Paper RM-224. Fort Collins: USFS Rocky Mountain Forest and Range Experiment Station.
Mooney, Harold A., G. St. Andre and R.D. Wright. 1962. Alpine and subalpine vegetation patterns in the White Mountains of California. American Midland Naturalist 68(2):257-273.
Morris, E.A. 1986. Charles Wesley Ferguson, 1922-1986 (obituary). Tree-Ring Bulletin 46:1. Available online at www.treeringsociety.org/TRBTRR/TRBvol46.pdf (accessed 2006.06.05).
Last Modified 2013-03-16