Lodgepole pine (Pinus contorta)

Lodgepole pine is a species which grows throughout the west, as far north as the Yukon and south to Baja California. It ranges east to the Black Hills of South Dakota and west all the way to the Pacific Ocean.

Four varieties of lodgepole pine have evolved to adapt to this wide range of ecological conditions. Three grow in California. The most widely distributed is the Sierra lodgepole or tamarack (Pinus contorta var. murrayana) found throughout the Sierra Nevada in the Klamath Mountains and farther south in the Transverse and Peninsular ranges. Descriptions of lodgepole pine in this summary refer to the Sierra lodgepole pine unless otherwise stated. 

 Lodgepole Pine Identification:

• Needles occur in pairs and are 1.2 to 2.4 inches long with sharp ends.
• Bark is thin and scaly and colored orange-brown to gray.
• Cones vary in shape from short and cylindrical to egg-shaped, 1.6 to 2.4 inches long with sharp, flat scales on the ends and often occur in clusters.

A coastal variety known as the shore, coast, or beach pine (Pinus contorta var. contorta) grows in a narrow band along the coast on bluffs and sand dunes from Mendocino County northward. A pygmy variety called the Bolander or Mendocino White Plains pine (Pinus contorta var. bolanderi) occurs in isolated patches in Mendocino County.

The fourth variety, the Rocky Mountain lodgepole or black pine, is an important timber species throughout the inland west but is not found in California

 Climate 

Lodgepole pine probably has the widest range of environmental tolerance of any conifer in North America. It grows in areas with cold, wet winters and warm, dry summers. In the southern part of its range, Sierra lodgepole pine grows under very dry conditions. The seasonal distribution of precipitation seems to be an important factor for determining its range. Snow melt in the spring supplies critical soil water which is used by the tree for rapid growth in early summer.

Lodgepole pine grows on a wide variety of soils, from water-logged organic soils to well-drained glacial outwashes. It grows best in moist soils derived from granite, shale, and coarse grained lavas. It also grows in soils with underlying hardpan. Lodgepole is frequently the only tree species found on infertile soils, although it grows better in fertile areas. It is seldom found on drier soils derived from limestone.

Lodgepole pine can grow well on a wide range of land forms including meadows, gentle slopes, and basins or steep and rocky slopes and ridges. It grows better on moister east and north facing slopes than on dry south or west facing slopes.

Lodgepole pine is a prolific, reliable seed producer. Trees produce viable seed by 5 to 10 years of age. Good seed crops occur at one- to three-year intervals with light crops in between. Pollen is shed in late June, and seed cones mature in late summer the year after pollination. Cones average 5 to 37 seeds each (117,000 seeds per pound) and open and disperse seed from late August to mid-October. Cones can withstand below freezing temperature and are not much affected by insects.

Sierra lodgepole does not sprout from the root crown, and its cones do not persist on the tree. Seeds are wind dispersed and can fall up to 200 feet from the tree. Studies in the Sierra have found 72 percent of seeds to be viable. Seed loss to birds and rodents does not greatly affect reproduction because of the heavy cone crops and high germination capacity of seeds.

Seeds germinate quickly after snow melt. Seedlings are threatened by drought and so survive best on bare mineral soil or disturbed litter which provide adequate soil moisture. Shading can inhibit seedling survival, although seedlings can live for many years in an understory of light shade. Seedlings are relatively poor competitors against grasses and may be excluded by a sod cover.

Lodgepole pine grows both in pure stands and in association with many western conifers. It is a component of the mixed-conifer forest as well as coastal forests and Jeffrey pine forests in the south. Lodgepole pine develops a shallow root system which is susceptible to windthrow.
Lodgepole is intermediate in water needs, requiring more than Douglas-fir and ponderosa pine. It can tolerate high water tables which allows it to dominate species such as ponderosa pine, redwood, or Douglas-fir on soils kept wet by an underlying hardpan. It also tolerates dry sites well.
Lodgepole pine is moderately shade tolerant and can establish in the understory of mixed-conifer stands, although only individuals which receive full sunlight will attain maximum vigor.

Sierra lodgepole pine typically grows to a height of 90 to 100 feet and an average diameter of 16 inches or greater. Trees growing near timberline are shrubby in form. The tree is long lived; some trees have lived in excess of 600 years.

Because lodgepole pine has little taper and thin bark, it produces a higher volume of wood for its size than many associated species. Natural pruning is poor, but limbs are generally small and so do not create large knots in the harvested wood.

Planted stands of Sierra lodgepole show good first- and second-year survival even on steep to moderate slopes and high bluffs. Rapid juvenile growth makes it a useful short-rotation crop in some areas.

Because of its relatively thin bark and shallow root system, Sierra lodgepole pine is more susceptible to fire than Douglas-fir and many other associates. Although it is usually killed by fire, fire is also key to regeneration of the species.

When fires occur in lodgepole stands, they are usually of enough intensity to kill all or most of the existing trees. Fires intense enough to burn down to bare mineral soil create an ideal seed bed for Sierra lodgepole seedlings. Unlike the Rocky Mountain lodgepole variety, Sierra lodgepole pine do not have serotinous cones which require intense heat to open.

Burned areas are typically colonized fairly quickly by wind-dispersed seed. These new seedlings then develop as an even-aged stand. Since the species is a prolific seeder, these stand are especially vulnerable to overstocking. Overstocking can result in limited growth and stagnant stands.

Lodgepole pine stands are often regenerated using even-aged silvicultural methods. This typically consists of clear cutting and natural regeneration or planting. Since stands are vulnerable to overstocking, thinning is a necessity, and in some areas, must be carried out as early as age 10 for the best response.

There is evidence that Sierra lodgepole pine is increasing in number in some Sierran white fir forests because fire suppression has reduced the number of fires which, historically, would have killed young lodgepole pine in mixed-conifer understories.

The coastal lodgepole pine varieties commonly grow as short, scrubby, crooked trees. These varieties have bark which is thick, deeply grooved, and dark reddish-brown. Trees are smaller but vary greatly. Mature shore pines range from 6 to 20 inches in diameter and 20 to 40 feet tall. The Mendocino White Plains pine variety is only 2 to 5 feet tall when mature. This dwarfing is probably a result of the soil conditions in which highly acidic soil covers a hardpan. Both varieties may have serotinous cones.

Mountain pine beetles play an important role in the dynamics of natural lodgepole pine stands. The beetle periodically invades stands, killing many individuals and creating large amounts of fuel. These fuels are eventually consumed by fire, creating a favorable seed bed for lodgepole regeneration. This cycle increases the probability that lodgepole pine will reoccupy a site at the expense of other species.

Adult beetles attack lodgepole pine in July or August by tunneling through the bark and laying eggs. Beetles introduce blue stain fungi, which in conjunction with larvae feeding on the bark, cause girdling which kills the tree. Larvae overwinter in the tree, complete their development, and emerge as adults in the spring to attack new trees. Epidemics can kill up to two thirds of a stand's large trees. Infestations commonly last 5 to 7 years, and reoccur in 20- to 40-year cycles.

Lodgepole pine is also susceptible to mistletoe, rusts, root rot, and fungal pathogens. Dwarf mistletoe is the most widespread and serious parasite affecting lodgepole pine. The rate of spread is fastest in dense stands. In many areas, more than 50 percent of lodgepole pine forests are infected and experience reduced vigor.

Seed and seedling diseases are not usually damaging, although several mold fungi prevent seed germination and cause rotting of young seedlings.

 Uses

Native Americans used the wood from lodgepole pine for a variety of purposes, including poles for their lodges. In the spring, long ribbons of the sugar-rich inner bark were stripped off to eat. This inner bark could be stored or mashed to make bread. Needles were used to make tea. The pitch was used as a base for medicines to treat rheumatic pain, aches and soreness in muscles and joints, and sore throats.

The wood of Sierra lodgepole pine is straight grained, light, and uniform in texture, with small knots, making it suitable for lumber, plywood, and paneling. It is used for light framing materials, doors, windows, and furniture. Lodgepole pine wood consistently dries straight and accepts treatment well, making it well suited for post and pole material including railway ties, mine props, and fence posts.

Lodgepole pine forests are important for food, cover, or habitat for birds and mammals as well as livestock grazing. Its capacity to regenerate well on poor soils, rocky slopes, and exposed sites has led to its wide spread planting in Great Britain and New Zealand.  

This text was largely summarized from an article originally by James E. Lotan Adjunct Professor, College of Forestry, Wildlife, and Range Sciences, University of Idaho, Moscow, ID; and William B. Critchfield Geneticist, Pacific Southwest Forest and Range Experiment Station, Berkeley, CA. that appears in Burns, Russell M., and Barbara H. Honkala, tech. coords. 1990. Silvics of North America: 1. Conifers. Agriculture Handbook 654. U.S. Department of Agriculture, Forest Service, Washington, DC. vol. 1, 675 p.

Interested readers are referred to the original article for more detailed and technical information and references 12. Nur - Light 155. Publication of this series was in part funded by the California Department of Forestry and Fire Protection under Contract numbers 8CA96027 and 8CA96028