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photograph

Mature ponderosa (subsp. ponderosa) growing in a selectively logged area, Big Hole, Oregon [C.J. Earle, 1998.04.17].

photograph

Bark, about 30 cm across, on a specimen of subsp. ponderosa [C.J. Earle].

photograph

Actively elongating shoot and start-of-second-summer cone on P. ponderosa subsp. ponderosa [C.J. Earle, 2002.05.25].

photograph

Stand of old-growth P. ponderosa near Whitney, Oregon, ca. 1900 [J. W. Cowden] (courtesy Gary Dielman, Baker City library).

off-site photos

 

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Conservation status

Pinus ponderosa

Douglas ex Lawson 1836

Common names

Ponderosa pine; yellow, western yellow, bull, black Jack, western red, western pitch, big, heavy, Sierra brownbark, or western longleaf pine; pino real, pinabete [Spanish]; pin à bois lourd [French].

Taxonomic notes

Discovered by David Douglas in 1826 near what is now Spokane, Washington (Little 1980) and described by Lawson in 1836. Since that time, the taxonomy of the ponderosa complex has been the subject of continuing dispute. The classification used here is fairly typical, relying on three principal taxa distinguished at the subspecies rank. It draws heavily on scholarship by Lauria (1991, 1996a, 1996b) and Frankis (previously unpublished). This analysis also relies heavily upon a detailed study of mitochondrial DNA haplotypes evaluated for 104 populations throughout the range of the species, with ca. 30 trees sampled per population (Potter et al. 2013).

The discussion below relies heavily upon a rather complex range map, formerly shown on this site, but now you have to download this KML file and open it in Google Earth, due to severe limitations in the display capabilities of the latest Google map interface (which supports only a minor subset of KML). The complete map includes:

Traditionally, forestry studies have indicated the existence of two to five distinct taxa, variously termed species, subspecies, varieties, 'races' (Weidmann 1939, Critchfield 1984, Conkle and Critchfield 1988) or 'ecotypes' (Wells 1964). These taxa are morphologically distinct (Lauria 1991, 1996a, 1996b). The following names, not all of which have been formally published, are used here:

P. ponderosa subsp. ponderosa includes populations formerly assigned to P. washoensis H. L. Mason & Stockwell (which is arguably a distinct taxon at the varietal rank), as well as those conventionally assigned to P. ponderosa subsp. ponderosa from British Columbia, western Montana, Idaho, and Washington, Oregon, California & Nevada east of the Cascades crest. Haplotype data indicate that a single haplotype (shown in cyan) predominates in the Montana, northern Idaho, northern Washington, and Cascade Range portion of the subspecies' range, while another haplotype, shown in purple, predominates in central Idaho and eastern Oregon. Analysis by Potter et al. (2013) shows that each of these haplotypes is, separately, closely related to the haplotype shown in light green, which predominates on the wet western side of the Cascades, Sierra Nevada, and points west. It may be that the cyan and purple haplotypes represent separate processes of radiation from a Pleistocene refugium located in a southern locale; Potter et al. (2013) cite paleoecological evidence of P. ponderosa occurrence in the southern Sierra Nevada during the last glacial maximum as the closest known presence of the species at that time. It is also possible that a refugium existed in the Klamath-Siskiyou region; although no fossil evidence has been found of P. ponderosa, many other plants are known to have weathered the last glacial maximum by persisting in this area.

P. ponderosa subsp. benthamiana (Hartw.) Silba (2009). The 'Pacific' group includes populations formerly assigned to Pinus benthamiana Hartweg (1847) from the Sierra Nevada and west of the Cascade crest in California, Oregon and Washington. These populations are most strongly and consistently allied with a haplotype shown in green, which is predominant in populations in the Puget Trough, the Willamette Valley, and the Klamath-Siskiyou region. Along the Sierra Nevada, this haplotype is present along with the purple haplotype that predominates in eastern Oregon and generally seems to be associated with populations of drier, colder, more continental environments. A variant haplotype found south of San Francisco Bay (shown in gray) is differentiated by a single mutation from the green haplotype.

Molecular clock analyses (Lascoux et al. 2004, cited by Potter et al. 2013) suggest that the separation (marked by the heavy blue line on the range map) between the coastal subspecies (ponderosa and benthamiana) and the interior subspecies (scopulorum) occurred more than 250,000 years ago, and (see discussion by Potter et al. [2013]) the division may have persisted since the onset of glacial/interglacial cycles at the Pliocene/Pleistocene boundary, or even earlier, with separation happening when tectonism created the Basin and Range structure of central Nevada in an area that formerly was montane plateau.

Pinus ponderosa subsp. scopulorum (Engelmann) E. Murray is the most widespread of the interior subspecies. Its range is largely disjunct from the coastal subspecies. Where the two distributions touch in west-central Montana, there appears to be no mixing of the mitochondrial haplotypes (probably because contact occurred relatively recently). The subject seems not to have been studied where the two distributions touch in southern California, but for many other plants in that area, the desert north of the Transverse Ranges marks a biogeographical boundary, and I have treated it so here. Five different mitochondrial haplotypes help to differentiate subspecies scopulorum; of these, the haplotypes shown in orange and dark blue predominate throughout most of the vast range north from Arizona and New Mexico to Montana. The two haplotypes are very closely related. There is no paleoecological evidence of P. ponderosa anywhere north of the Mogollon Rim in Arizona and New Mexico during the last glacial maximum, yet it seems to have radiated into much of its modern range within a few thousand years of the beginning of the Holocene; the interspersed pattern of dominance by the orange and dark blue haplotypes may represent a legacy of this rapid dispersal.

Near the southern range limits of the subspecies, however, the picture becomes more complex. Populations south of the Arizona-Utah border have sometimes been treated under Pinus brachyptera Engelmann (1848) in Arizona and New Mexico. In the far south of those states, P. ponderosa is replaced by Pinus arizonica (q.v.), a closely related taxon that is distributed primarily in Mexico. The predominant haplotype in Arizona and New Mexico is shown in orange on the range map. However three other distinctive haplotypes, each closely related to the others (and to the orange type), do occur in the region: a blue-green type predominates in eastern Nevada and western Utah, and may represent radiation from a different Pleistocene refugium compared to the source of the orange and dark blue haplotypes. There is also a haplotype shown in yellow that occurs in a disjunct pattern in southern California and southern Nevada, and in southeast New Mexico; in southern Nevada, it is associated with a closely related haplotype shown in red. The cause of this disjunct pattern is not known, but may represent a consequence of northward dispersal from a former Mexican refugium during climatic warming and drying since the last glacial maximum.

Description

Trees to 18-39(72) m with 80-120(250) cm diameter, straight; crown broadly conic to rounded. Bark yellow- to red-brown, deeply irregularly furrowed, cross-checked into broadly rectangular, scaly plates. Branches descending to spreading-ascending; twigs stout (to 2 cm thick), orange-brown, aging darker orange-brown, rough. Buds ovoid, to 2 cm, 1 cm broad, red-brown, very resinous; scale margins white-fringed. Needles 2-5 per fascicle, spreading to erect, persisting (2)4-6(7) years, 7-25(30) cm × (1)1.2-2 mm, slightly twisted, tufted at twig tips, pliant, deep yellow-green, all surfaces with evident stomatal lines, margins serrulate, apex abruptly to narrowly acute or acuminate; sheath 1.5-3 cm, base persistent. Staminate cones ellipsoid-cylindric, 1.5-3.5 cm, yellow or red. Ovulate cones maturing in 2 years, shedding seeds soon thereafter, leaving rosettes of scales on branchlets, solitary or rarely in pairs, spreading to reflexed, symmetric to slightly asymmetric, conic-ovoid before opening, broadly ovoid when open, 5-15 cm, mostly reddish brown, sessile to nearly sessile, scales in steep spirals (as compared to Pinus jeffreyi) of 5-7 per row as viewed from side, those of cones just prior to and after cone fall spreading and reflexed, thus well separate from adjacent scales; apophyses dull to lustrous, thickened and variously raised and transversely keeled; umbo central, usually pyramidal to truncated, rarely depressed, merely acute, or with a very short apiculus, or with a stout-based spur or prickle. Seeds ellipsoid-obovoid; body (3)4-9 mm, brown to yellow-brown, often mottled darker; wing 15-25 mm (Little 1980, Kral 1993).

There is clinal variation in characters within each of the subspecies, and it seems not to have been well studied or described. I have found that in Washington and Oregon, subsp. benthamiana has slightly larger cones, with a recurved prickle, while subsp. ponderosa has smaller cones, with an incurved prickle.

Distribution and Ecology

Canada: S British Columbia, E to US: SW North Dakota, S to trans-Pecos Texas and W to S California; also in Mexico: Baja California and Sonora (Little 1980, Kral 1993). See the range map shown above. Mostly in the mountains, in pure stands or mixed conifer forests (Little 1980). See also Thompson et al. (1999). Hardy to Zone 4 (cold hardiness limit between -34.3°C and -28.9°C) (Bannister and Neuner 2001, subspecies not specified), but I would expect this to vary significantly according to subspecies and provenance.

Ponderosa pine presents one of the best examples of the superb adaptation to wildfire that characterizes much of the genus Pinus. Studies in the Gila Wilderness area of Arizona and New Mexico have found that due to frequent summer lightning storms and the accumulation of pine needles on the forest floor, low intensity surface fires may travel through ponderosa stands with an average frequency of once every three years. These frequent burns discourage competitive species such as scrub oak and shade tolerant conifers. Adult ponderosa are unharmed by such fires due to their thick, fire resistant bark, while ponderosa seedlings also have an excellent chance of surviving these low-intensity burns. In the historical period, an enthusiastic program of fire suppression has virtually eliminated these small, frequent fires. As a consequence, shrubs and shade-tolerant conifers have invaded many ponderosa stands while thick accumulations of highly combustible fuels have built up on the forest floor. Now, when a fire does occur, it is likely to be extremely destructive, destroying vast stands of prime forest. Since the mid-1970s, some forest managers have attempted to reintroduce low intensity fire to this ecosystem, but their efforts are often thwarted both by a "Smokey the Bear" mentality ingrained in the public mind, and by the high cost of monitoring prescribed fire in an ecosystem that has accumulated high fuel loads.

The same problem can also be viewed from a historical perspective. Early travelers in the West often commented on the vast, parklike stands of ponderosa pine that they encountered. There are tales of stands of giant trees separated by grassy swards, with no other understory vegetation. Many of these stands were so open and level that a carriage could easily be driven through them, and some writers report stands of this character so extensive that they took days to ride across. Such a stand is shown in the photograph at left, taken in the woods near Whitney, Oregon in about 1900. That forest was logged over long ago. It is still possible to see such a forest, but to do so you must go to Mexico, specifically to the Sierra San Pedro Martír in Baja California. That is a forest of Pinus lambertiana, Pinus jeffreyi, Pinus coulteri and Abies concolor var. lowiana, but the open character and giant trees are highly reminiscent of pioneer accounts of Pinus ponderosa forests of the West. Interestingly, very similar accounts describe early historical forests of Pinus palustris in the southeastern U.S., although the trees were not so massive as those seen in the photograph at left. In each of these forests, the giant trees and open understory were a legacy of frequent, low-intensity fire that excluded competitors, discouraged root rot fungi, and maintained an optimum growing environment for the dominant canopy tree species.

Big tree

See subspecies benthamiana.

Oldest

Subspecies scopulorum has attained 1,047 years (ring count).

Dendrochronology

Ethnobotany

This is the most commercially important western pine (Little 1980). Extensive harvest has eliminated vast acreages of old growth ponderosa.

The Nez Perce indians used to harvest the inner bark to feed their horses in early spring when better forage was still buried deeply beneath the snows. The cambium would be scraped for food (often only in times of famine) by the Apache, Chiricahua, Mescalero, Navajo, Paiute, Klamath, Sanpoil, Spokan, Colville, Okanogan, and Thompson. Nearly everyone ate the seeds, usually roasted, sometimes ground into a flour. The pitch or sap was used by many tribes including the Cheyenne, Flathead, Okanogan, Colville, Paiute, and Thompson for a wide variety of purposes including as a salve or ointment for sores, boils, cuts and earache; to reduce inflammation of the eyes; to treat backache or rheumatism; and to pacify babies by spreading it on their skin. Decoctions of green leaves were put to similar uses. Many tribes used the pitch as a glue or sealer; the Cheyenne used it to tune flutes and whistles. The Digueno would make baskets from the needles and the Karok and Maidu would do the same with the roots. The wood was widely used in structures, to make dugout canoes, and for other uses such as cradle boards, ladders, and of course firewood (University of Michigan Ethnobotany Database 2013.09.07).

Observations

See the subspecies descriptions.

Remarks

This is the most widely distributed and common pine in North America. Quail, squirrels and many other kinds of wildlife consume the seeds, and nutcrackers and chipmunks cache them, thereby helping to bring forth new pines (Little 1980).

Ponderosa pine (Pinus ponderosa) is the state tree of Montana (Kral 1993).

Citations

Lascoux, M., A.E. Palme, R. Cheddadi, and R.G. Latta. 2004. Impact of Ice Ages on the genetic structure of trees and shrubs. Philosophical Transactions of the Royal Society of London. B, Biological Sciences 359:197-207.

Lawson, P. 1836. Agriculturist's Manual. Edinburgh (p. 354).

Potter, K.M., V.D. Hipkins, M.F. Mahalovich, and R.E. Means. 2013. Mitochondrial DNA haplotype distribution patterns in Pinus ponderosa (Pinaceae): range-wide evolutionary history and implications for conservation. American Journal of Botany 100(8):1-18.

Silba, J. 2009. Journal of the International Conifer Preservation Society 16(1): 30.

M.P. Frankis contributed much to the development of this page in 1998.12.

See also

Allen, Craig D. 1995. A Ponderosa Pine Natural Area Reveals Its Secrets. In Status and Trends of the Nation's Biological Resources. USGS electronic publication. http://biology.usgs.gov/s+t/SNT/noframe/sw153.htm, accessed 2002.09.03.

Burns & Honkala 1990.

Lanner 1983.

FEIS database.

Last Modified 2014-12-12