Pinus longaeva

Great Basin bristlecone pine

Pinaceae

The Basics

Taxonomy: Kingdom - Plantae (plants). Subkingdom - Tracheobionta (vascular plants). Superdivision - Spermatophyta (seed plants). Division - Coniferophyta (conifers). Class - Pinopsida. Order - Pinales. Family - Pinaceae (pine). Genus - Pinus L. Species - Pinus longaeva D. K. Bailey

Ecology: Great Basin bristlecone pine is a long living high-elevation native conifer of highly variable growth form. At lower elevations, trees are typically upright, while at high elevations Great Basin bristlecone pine becomes twisted and contorted. Great Basin bristlecone pine may have single or multiple trunks. Unlike foxtail pine, which has very thick bark, Great Basin bristlecone pine bark is thin. Great Basin bristlecone pines on harsh sites have a high proportion of dead trunk and branchwood. Old trunks and exposed roots have thick, vertical ribbons of dead wood. Between the dead wood, thin strips of living root and stem tissue support living branches. The Great Basin bristlecone pine's root system is mostly composed of highly branched, shallow roots. A few large, branching roots provide structural support. In old age, structural roots may buttress when denudation exposes large lateral roots. Pinus longaeva can reach extremely old ages. The oldest known living organism is a 5,065 year old Great Basin bristlecone pine in the White Mountains of California. Other Pinus longaeva in Nevada, Utah, and Arizona have been found to be 1,000 to 5,000 years old. Great Basin bristlecone pine communities are very open at high elevations, and understories are sparse. Great Basin bristlecone pine is both a pioneer species and, on open harsh sites, a climax species. Great Basin bristlecone pine establishes and shows rapid, vigorous growth on open mesic sites. However, it competes poorly for water and nutrients, and is usually excluded from good sites. It is considered a topoedaphic climax species on droughty sites with nutrient-poor soils. The limestone soils that favor Great Basin bristlecone pine are too low in phosphorus to support potential competitors. On these dry, nutrient-poor sites, Great Basin bristlecone pine outcompetes associated species including limber pine.Great Basin bristlecone pine is shade intolerant and cannot establish in dense forest.

In the Utah Forest Dynamics Plot, Pinus longaeva is the 5th most common species by number of stems, but it represents a disproportionate amount of the basal area, second only to Populus tremuloides and Abies bifolia.

Identification

Trees to 16m; trunk to 2m diam., strongly tapering; crown rounded, flattened (sheared), or irregular. Bark red-brown, shallowly to deeply 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. Buds ovoid-acuminate, pale red-brown, ca. 1cm, resinous. Leaves mostly 5 per fascicle, upcurved, persisting 10--30 years, 1.5--3.5cm 0.8--1.2mm, mostly connivent, deep yellow-green, with few resin splotches but often scurfy with pale scales, abaxial surface without median groove but with 2 subepidermal but evident resin bands, adaxial surfaces conspicuously whitened with stomates, margins entire or remotely and finely serrulate distally, apex bluntly acute to short-acuminate; sheath ca. 1cm, soon forming rosette, shed early. Pollen cones cylindro-ellipsoid, 7--10mm, purple-red. Seed cones maturing 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--9.5cm, 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--6mm, resin exudate pale. Seeds ellipsoid-obovoid; body 5--8mm, pale brown, mottled with dark red; wing 10--12mm.

Threats

Fire effects: based on its thin bark, Great Basin Bristlecone Pine is adapted to survive only low-severity surface fires. With low productivity and widely spaced stands, there are usually not enough fuels to carry fire in high-elevation Great Basin Bristlecone Pine sites. When fires do occur at high elevations, they are typically small, low-severity surface fires. Stand dynamics in these areas are generally more influenced by climate and seed dispersal patterns than by fire.

Pests and pathogens: Mountain pine beetle, dwarf mistletoe, wood-rot basidiomycetes and wood decay fungi are all known to infest Great Basin Bristlecone Pine. The dry high-elevation sites of most Great Basin Bristlecone Pine currently serve to slow fungal growth and wood decay.

White pine blister rust: Bristlecone Pine is one of the five-needle pines susceptible to the exotic pathogen, White Pine Blister Rust (Cronartium ribicola A. Dietr.). Blister rust resistance is being evaluated at the USDA Forest Service, Institute of Forest Genetics, Placerville, CA. Preliminary results show no evidence of the hypersensitive response with 30% of the seedlings canker-free. Both Rocky Mountain Bristlecone Pine (Pinus aristata Engelm.) and Great Basin Bristlecone Pine are highly resistant to blister rust, in part due to wax-occluded stomata. In addition, the predominant alternate host, Ribes cereum, is highly resistant to infection by aeciospores, thereby making it difficult for the rust to complete its life cycle in the alternate host.  However, levels of resistance of Great Basin Bristlecone Pine to blister rust remain unclear. Laboratory studies have shown Great Basin Bristlecone Pine seedlings to be lacking key alleles that confer genetic resistance to blister rust. Populations in the White and Inyo Mountains, which lie close to moderately high infection centres in the Sierra Nevada, may be at greatest risk for blister rust infection and spread.

Reproduction

Seed production - Great Basin bristlecone pine does not mast, but is a steady cone and seed producer. Great Basin bristlecone pine is monoecious. Great Basin bristlecone pine is pollinated by wind. Great Basin bristlecone pines on desert "sky islands" are susceptible to inbreeding due to poor pollen and seed dispersal. Clark's nutcrackers bury seeds in caches. A growth form of clumped trees that fuse at the stem is characteristic of establishment resulting from Clark's nutcracker seed dispersal.

Seedling establishment - Seedling establishment is a rare event for Great Basin bristlecone pine. Since Great Basin bristlecone pine primarily grows on dry, nutrient-poor soils, conditions favorable to Great Basin bristlecone pine germination and growth are infrequent. Great Basin bristlecone pine growing on high-elevation sites age very slowly.

Vegetative regeneration: none.

Species Distribution

Citation

Oldlist
Pinus longaeva age. Rocky Mountain Tree Ring Research.

IUCN Red List
Stritch, L., Mahalovich, M. & Nelson, K.G. 2011. Pinus longaeva: least concern. The IUCN Red List of Threatened Species.

USDA Plants Database
USDA, NRCS. 2016. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA.

USFS Plant Database
Habeck, R. J. 1992. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.

Flora of North America
Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 19+ vols. New York and Oxford.

The Jepson Herbarium
The Jepson Manual: Vascular Plants of California. B.G. Baldwin, D.H. Goldman, D.J. Keil, R. Patterson, T.J. Rosatti, and D.H. Wilken [editors]. 2012. 2nd edition, thoroughly revised and expanded. University of California Press, Berkeley, CA.

USGS Plant Species Range Maps
Critchfield, W.B., and Little, E.L., Jr., 1966, Geographic distribution of the pines of the world: U.S. Department of Agriculture Miscellaneous Publication 991, p. 1-97. Little, E.L., Jr., 1971-1978, Atlas of United States trees, volume 1,3,13,17, conifers and important hardwoods: U.S. Department of Agriculture Miscellaneous Publications.