Pinus lambertiana

Sugar 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 lambertiana Douglas

Ecology: Sugar pine is primarily an early-seral to seral species. It is rarely found in pure stands. When sugar pine is found to be the dominant species in old-growth stands, it most often was dominant to begin with or released by natural causes. White fir would usually be the climax species in mixed conifer forest in the absence of any natural disturbances. When disturbance does occur, it creates gaps in which sugar pine is well adapted to grow.

Identification

Trees to 75m; trunk to 3.3m diam., massive, straight; crown narrowly conic, becoming rounded. Bark cinnamon- to gray-brown, deeply furrowed, plates long, scaly. Branches spreading, distal branches ascending; twigs gray-green to red-tan, aging gray, mostly puberulent. Buds cylindro-ovoid, red-brown, to 0.8cm, resinous. Leaves 5 per fascicle, spreading to ascending, persisting 2--4 years, 5--10cm (0.9--)1--1.5(--2)mm, straight, slightly twisted, pliant, blue-green, abaxial surface with only a few lines evident, adaxial surfaces with evident white stomatal lines, margins finely serrulate, apex acuminate; sheath (1--)1.5--2cm, shed early. Pollen cones ellipsoid-cylindric, to 15mm, yellow. Seed cones maturing in 2 years, shedding seeds and falling soon thereafter, often clustered, pendent, symmetric, cylindric before opening, lance-cylindric to ellipsoid-cylindric when open, 25--50cm, yellow-brown, stalks 6--15cm; apophyses somewhat thickened; umbo terminal, depressed, resinous, slightly excurved. Seeds obovoid, oblique apically; body 1--2cm, deep brown; wing broad, 2--3cm.

Threats

Fire effects: Sugar pine is very resistant to low- to moderate-severity fires. It has adapted a thick, fire-resistant bark and open canopy that retards aerial fire spread. Young sugar pine seedlings prefer bare mineral seedbeds. Sugar pine is rated as intermediate in fire tolerance. Young sugar pines are susceptible to low- to high-severity fires. Mature trees can survive most fires, suffering only bole scorch.

Pests and pathogens: Sugar pine is highly susceptible to white pine blister rust caused by the fungus Cronartium ribicola. Infected seedlings and young trees are inevitably killed by cankers girdling the main stem. Dwarf mistletoe (Arceuthobium californicum) may seriously damage infected trees, but spread is slow and can be controlled by sanitation cutting. The most damaging insect threatening sugar pine is the mountain pine beetle (Dendroctonus ponderosae). During periods of drought, other insects such as the red turpentine beetle (D. valens) and California flathead borer (Melanophila californica) usually attack unhealthy trees and those under moisture stress. The sugar pine cone beetle (Conophthorus lambertianae) is extremely destructive to developing second-year cones.

Reproduction

Flowering and fruiting - Sugar pine is monoecious. Reproductive buds are set in July and August, but are not discernible until late the next spring. Time of pollination ranges from late May to early August, depending on elevation. Female strobili are approximately 2.5-5.0 cm long when pollinated and may double in size by the end of the growing season. Fertilization occurs the following spring, approximately 12 months after pollination. Dates of cone opening range from mid-August at low elevations to early October at high elevations. Sugar pine does not become a good cone producer until it has attained a diameter of about 75 cm or is about 150 years old.

Seed production and dissemination - Mature trees produce large amounts of seeds, averaging up to 150 seeds per cone. In good crop years, the proportion of sound seeds is usually high (67 to 99 percent) but in light crop years can fall as low as 28 percent. Seed shed may begin in late August at low elevations and at higher elevations is usually complete by the end of October. Seeds are large and heavy, averaging 4,630 seeds per kg. Seeds are not dispersed great distances by wind, and 80 percent fall within 30 m of the source. Birds and small mammals aid in seed dissemination.

Seedling development - Sugar pine seeds may lie dormant, but dormancy can be broken by a 60 to 90 day stratification. Fresh seed may germinate with a 90 percent success rate if adequately ripened, cleaned, and stratified. Losses due to unprepared seedbeds, drought, insects, and rodents may be high. Germination is epigeal. Seedlings rapidly grow a deep taproot when seeds germinate on mineral soil. Seedlings will germinate on both litter and bare mineral soil, but development is slow under shade conditions. After 2 years, taproots range from 22 to 56-102 cm deep.

Vegetative Reproduction - Sugar pine does not sprout, but young trees can be rooted from cuttings.

Species Distribution

Citation

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.

Silvics of North America
Burns, R.M., and B.H. Honkala. 1990. Silvics of North America (Volume 1: Conifers, Volume 2: Hardwoods). USDA Forest Service Agricultural Handbook 654.