Pinus contorta

Pinaceae -- Pine family

    James E. Lotan and William B. Critchfield

    Lodgepole pine (Pinus contorta) is a two-needled pine of the  subgenus Pinus. The species has been divided geographically into  four varieties: P. contorta var. contorta, the coastal  form known as shore pine, coast pine, or beach pine; P. contorta var.  bolanderi, a Mendocino County White Plains form in California  called Bolander pine; P. contorta var. murrayana in the  Sierra Nevada, called Sierra lodgepole pine or tamarack pine; and P.  contorta var. latifolia, the inland form often referred to as  Rocky Mountain lodgepole pine or black pine. Although the coastal form  grows mainly between sea level and 610 m (2,000 ft), the inland form is  found from 490 to 3660 m (1,600 to 12,000 ft).

Lodgepole pine is an ubiquitous species with a wide ecological  amplitude. It grows throughout the Rocky Mountain and Pacific coast  regions, extending north to about latitude 64° N. in the Yukon  Territory and south to about latitude 31° N. in Baja California, and  west to east from the Pacific Ocean to the Black Hills of South Dakota.  Forests dominated by lodgepole pine cover some 6 million ha (15 million  acres) in the Western United States and some 20 million ha (50 million  acres) in Canada.

     
- The native range of lodgepole pine.

Pinus contorta Douglas ex Loudon:
Mexico (Mesoamerica)
United States (North America)
China (Asia)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Extensive range from Alaska to northern New Mexico and Baja California, attaining best populations in the Rocky Mountains (Record and Hess 1943).

Tree, Shrub, Evergreen, Monoecious, Habit erect, Trees without or rarely having knees, Tree with bark rough or scaly, Young shoots 3-dimensional, Buds resinous, Leaves needle-like, Leaves alternate, Needle-like leaf margins finely serrulate (use magnification or slide your finger along the leaf), Leaf apex acute, Leaf apex obtuse, Leaves < 5 cm long, Leaves > 5 cm long, Leaves < 10 cm long, Leaves yellow-green above, Leaves yellow-green below, Leaves not blue-green, Needle-like leaves triangular, Needle-like leaves twisted, Needle-like leaf habit erect, Needle-like leaves per fascicle mostly 2, Needle-like leaf sheath persistent, Twigs glabrous, Twigs viscid, Twigs not viscid, Twigs without peg-like projections or large fascicles after needles fall, Berry-like cones orange, Woody seed cones < 5 cm long, Woody seed cones > 5 cm long, Seed cones bearing a scarlike umbo, Umbo with missing or very weak prickle, Umbo with obvious prickle, Bracts of seed cone included, Seeds red, Seeds brown, Seeds black, Seeds winged, Seeds unequally winged, Seed wings prominent, Seed wings equal to or broader than body.

Shrubs or trees to 50m; trunk to 0.9m diam., straight to contorted; crown various according to genetic race. Bark brown to gray- or red-brown, platy to furrowed. Lower branches often descending, the upper spreading or ascending. Twigs slender, orange to red-brown, aging darker brown, rough. Buds narrowly to broadly ovoid, dark red-brown, to 1.2cm, slightly resinous. Leaves 2 per fascicle, spreading or ascending, persisting 3--8 years, 2--8cm ´ 0.7--2(--3)mm, twisted, yellow-green to dark green, all surfaces with fine stomatal lines, margins finely serrulate, apex blunt to acute or narrowly acuminate; sheath 0.3--0.6(--1)cm, persistent. Pollen cones ellipsoid to cylindric, 5--15mm, orange-red. Seed cones maturing in 2 years or variably serotinous, variably persistent, spreading to reflexed, often curved, nearly symmetric or variably asymmetric, lanceoloid to ovoid before opening, broadly ovoid to nearly globose when open, 2--6cm, tan to pale red-brown, lustrous, nearly sessile or on stalks to 1cm; apophyses nearly rhombic, variously elongate, cross-keeled, often mammillate toward outer cone base and on inside above middle; umbo central, depressed-triangular, prickle barely elongate to stubby or slender and to 6mm. Seeds compressed, obovoid; body ca. 5mm, red-brown, mottled with black, or all black; wing 10--14mm. 2 n =24 (variety not indicated).

Lodgepole pine grows on soils that vary widely but are usually moist.  Growth is best where soil parent materials are granites, shales, and  coarse-grained lavas (24,27); other soils have developed from glacial till  of widely varying composition, Recent, Tertiary, and Oligocene alluvium  and colluvium (from such sources as quartzites and argillites), limestone  of the Belt geologic series, pumice, and volcanic ash. Lodgepole pine is  seldom found on the generally drier soils derived from limestone. In  Canada, however, extensive stands occur on calcareous glacial tills (56).  Glacial drift provides a balance of moisture and porosity on which the  species seems to thrive, as in Alberta, where it grows better on glacial  tills than on alluvial soils or lacustrine deposits. In Montana, highly  calcareous soils derived from dolomitic limestone usually do not support  lodgepole pine, subalpine fir (Abies lasiocarpa), and Engelmann  spruce (Picea engelmannii), although they do support Rocky  Mountain Douglas-fir (Pseudotsuga menziesii var. glauca). Nevertheless,  soils developed in colluvium from other types of limestone and calcareous  glacial till do support stands of lodgepole pine.

    Extensive stands of lodgepole pine (var. latifolia) occur on  soils classified as Inceptisols or Alfisols in the interior forests.  Although the species commonly grows on Andepts and does well on these  soils in some areas, the Boralfs and Ochrepts probably support better tree  development and more extensive stands. Frequently lodgepole pine soils on  Boralfs and Ochrepts have cryic soil temperature regimes. In the Blue  Mountains of Oregon lodgepole pine does well on Andepts, where it is  nearly always found on volcanic ash or alluvial material overlying  residual basaltic soils, at elevations between 910 and 2130 m (3,000 and  7,000 ft). The ash cap soils are deeper and hold more moisture than the  residual soils.

    The coastal form of lodgepole pine (var. contorta) is often  found on Histosols (peat bogs or muskegs) in southeastern Alaska, British  Columbia, and western Washington, and on dry, sandy, or gravelly sites  farther south along the coast on Inceptisols, Alfisols, and Ultisols.

    Soil properties and soil moisture often favor lodgepole pine locally  over other species. Lodgepole pine grows on wet flats and poorly drained  soils in the Cascade Range in Washington and Oregon, and the Sierra Nevada  in California. Soils with underlying hardpan support lodgepole pine to the  exclusion of such species as ponderosa pine (Pinus ponderosa), redwood  (Sequoia sempervirens), or Douglas-fir in the Sierra Nevada,  eastern Oregon, and Mendocino County, CA. Lodgepole pine also grows on  level sites with and without high water tables in central Oregon where  frost tolerance during germination allows its establishment to the  exclusion of other species. Extensive stands are found in these areas on  well drained sites above 1600 m (5,250 ft), with patterns of occurrence  attributed to past fires.

    On infertile soils, lodgepole pine is often the only tree species that  will grow. Nevertheless, experiments have demonstrated significant growth  increase from fertilization, particularly nitrogen (15).

    Lodgepole pine thrives in a wide variety of topographic situations. It  grows well on gentle slopes and in basins, but good stands are also found  on rough and rocky terrain and on steep slopes and ridges, including bare  gravel. Northern and eastern slopes are more favorable than southern and  western aspects (3).

Lodgepole pine grows under a wide variety of climatic conditions (52).  Temperature regimes vary greatly. Minimum temperatures range from 7°  C (45° F) on the coast to -57° C (-70° F) in the Northern  Rocky Mountains. Maximum temperatures range from 27° C (80° F)  along the coast and at high elevations to well over 38° C (100°  F) at low elevations in the interior. Average July minimums frequently are  below freezing at high elevations. Lodgepole seedlings are relatively  resistant to frost injury in some locations (16,42) and often survive in "frost-pockets"  where other species do not.

    At low elevations in the interior, lodgepole pine grows in areas  receiving only 250 mm (10 in) of mean annual precipitation, whereas it  receives more than 500 mm (200 in) along the northern coast. Many interior  sites often are low in summer rainfall. Seasonal distribution of  precipitation is significant; snowfall supplies most of the soil water  used for rapid growth in early summer. Temperatures are frequently  favorable for germination after snowmelt, and germination occurs rapidly.  Lodgepole is very intolerant of shade and generally grows best in full  sunlight.

Systems

• Terrestrial

Comments: Thrives in mostly well drained soils but may be found in peat bogs, muskegs or on dry sandy sites (Tree Talk 1994).

Foodplant / parasite
aecium of Coleosporium asterum parasitises live Pinus contorta

In Great Britain and/or Ireland:
Foodplant / mycorrhiza / ectomycorrhiza
fruitbody of Cortinarius malicorius is ectomycorrhizal with live root of Pinus contorta
Remarks: Other: uncertain
Other: major host/prey

Foodplant / saprobe
fruitbody of Dacryobolus sudans is saprobic on decayed wood of Pinus contorta

Foodplant / pathogen
Brunchorstia anamorph of Gremmeniella abietina infects and damages live twig of Pinus contorta
Other: unusual host/prey

Plant / associate
fruitbody of Hebeloma arenosa is associated with Pinus contorta

Foodplant / internal feeder
larva of Hylobius abietis feeds within dead stump of Pinus contorta
Other: major host/prey

Foodplant / sap sucker
nymph of Leptoglossus occidentalis sucks sap of unripe seed (in 1-year old cone) of Pinus contorta
Remarks: season: 5-8
Other: major host/prey

Foodplant / saprobe
Cryptosporiopsis anamorph of Pezicula livida is saprobic on dead, fallen branch of Pinus contorta

Foodplant / pathogen
fruitbody of Phaeolus schweinitzii infects and damages live root of mature tree of Pinus contorta
Other: minor host/prey

Foodplant / pathogen
pycndium of Ramichloridium anamorph of Ramichloridium pini infects and damages shoot (young) of Pinus contorta

Fungus / saprobe
conidioma of Sirococcus coelomycetous anamorph of Sirococcus conigenus is saprobic on fallen cone of Pinus contorta

Foodplant / saprobe
effuse colony of Troposporella dematiaceous anamorph of Troposporella monospora is saprobic on dead needle of Pinus contorta

Lodgepole pine grows both in extensive, pure stands, and in association  with many western conifers. The forest cover type Lodgepole Pine (Society  of American Foresters Type 218) (26) exists as a pure (80 percent or more)  component of basal area stocking, as a majority (50 percent or more), or  as a plurality (20 percent or more). The cover type includes all  recognized subspecies of Pinus contorta.

    Lodgepole pine is a component in 27 of the 55 SAF western forest cover  types. In the Northern Interior (Boreal) group it is represented in White  Spruce (Type 201), White Spruce-Aspen (Type 251), White Spruce-Paper Birch  (Type 202), Paper Birch (Type 252), and Black Spruce (Type 204).

    It is a component in all six high elevation cover types: Mountain  Hemlock (Type 205), Engelmann Spruce-Subalpine Fir (Type 206), Red Fir  (Type 207), Whitebark Pine (Type 208), Bristlecone Pine (Type 209), and  California Mixed Subalpine (Type 256). At middle elevations in the  interior it is a minor component of seven other types: Interior  Douglas-Fir (Type 210), Western Larch (Type 212), Grand Fir (Type 213),  Western White Pine (Type 215), Blue Spruce (Type 216), Aspen (Type 217),  and Limber Pine (Type 219). In the North Pacific forests, it is a  component in Coastal True Fir (Type 226), Western Redcedar-Western Hemlock  (Type 227), Western Redcedar (Type 228), Douglas-Fir-Western Hemlock (Type  230), Port-Orford-Cedar (Type 231), and Redwood (Type 232). At low  elevations in the interior it is associated with Interior Ponderosa Pine  (Type 237) and in the South Pacific forests it is a component of Jeffrey  Pine (Type 247).

    Lodgepole pine, with probably the widest range of environmental  tolerance of any conifer in North America, grows in association with many  plant species (30,50,59,60). The lodgepole pine forest type is the third  most extensive commercial forest type in the Rocky Mountains.

    Lodgepole pine's successional role depends upon environmental conditions  and extent of competition from associated species. Lodgepole pine is a  minor seral species in warm, moist habitats and a dominant seral species  in cool dry habitats. It is often persistent even on cool and dry sites  and can attain edaphic climax at relatively high elevations on poor sites.  Fire regimes have played a role in this successional continuum, especially  where repeated fires have eliminated a seed source for other species (27).  Lodgepole pine may even overwhelm a site with seed stored in serotinous  cones. It has four basic successional roles (50):

    Minor Seral- A component of even-aged stands rapidly being  replaced by shade-tolerant associates in 50 to 200 years.

    Dominant Seral- The dominant cover type of even-aged stands with  a vigorous understory of shade-tolerant species that will replace  lodgepole pine in 100 to    200 years.

    Persistent- The dominant cover type of even-aged stands with  little evidence of replacement by shade-tolerant species.

    Climax- The only tree species capable of growing in a particular  environment; lodgepole pine is self-perpetuating.

The mountain pine beetle (Dendroctonus  ponderosae) is the most severe insect pest of lodgepole pine. The  epidemics that periodically occur in many lodgepole pine stands seriously  affect the sustained yield and regulation of managed stands.

    Adult beetles attack lodgepole pine in July or August, introducing  bluestain fungi (8). The beetles construct egg galleries in the phloem  where larvae feed and together with the fungi, girdle and kill the tree.  Larvae overwinter in the tree, complete development, and emerge as adult  beetles in the spring.

    Harvesting has been considered as a means of preventing mountain pine  beetle epidemics (19). Silvicultural practices in an integrated program  for controlling losses to mountain pine beetle have been suggested (9,18).  No mortality occurred in heavily thinned stands in Oregon where vigor  ratings were high (44).

    The mountain pine beetle has played an historic role in the dynamics of  lodgepole pine ecosystems. By periodically invading stands and creating  large amounts of fuels, which are eventually consumed by fire, creating  favorable conditions for regeneration (12,39), the beetle has increased  the probability that lodgepole pine will reoccupy the site at the expense  of other species.

    Another aggressive bark beetle that attacks lodgepole pine is the pine  engraver (Ips pini). Ips commonly develops in logging slash,  especially slash that is shaded and does not dry quickly. Prompt slash  disposal is an effective control measure. Ips also can build up in  windthrows.

    Other insects that can be damaging local pests are the lodgepole  terminal weevil (Pissodes terminalis), which can be destructive to  elongating terminal leaders; larvae of the Warren's collar weevil (Hylobius  warreni), which girdles roots and the root collar; larvae of the  weevil Magdalis gentilis, which mine branches; various sucking  insects, such as the pine needle scale (Chionaspis pinifoliae), the  black pineleaf scale (Nuculaspis californica), and the spruce  spider mite (Oligonychus ununguis); and several defoliating  insects, among which are the lodgepole sawfly (Neodiprion burkei),  the lodgepole needle miner (Coleotechnites milleri), the sugar  pine tortrix (Choristoneura lambertiana), the pine tube moth (Argyrotaenia  pinatubana), and the pandora moth (Coloradia pandora) (7).

    Dwarf mistletoe (particularly Arceuthobium americanum) is the  most widespread and serious parasite affecting lodgepole pine (11,29).  A. americanum seeds are forcibly ejected from the fruit for  distances as great as 9 m (about 30 ft). The sticky seeds adhere to the  foliage of potential host trees. The proportion of trees visibly infected  can double each 5 years between the ages of 10 and 25, with nearly a third  of the trees infected at age 25 (29).

    Rate of spread in young stands is about 0.3 to 0.5 m (1.0 to 1.5 ft) per  year, with the fastest rate in dense stands. In many areas, more than 50  percent of lodgepole pine forests are infected. Dwarf mistletoe infection  results in reduced diameter and height growth, increased mortality,  reduced wood quality, decreased seed production, and overall decreased  vigor.

    Both harvesting and fire can greatly lessen the rate of spread and rates  of infection. Effective control can be accomplished by clearcutting and  locating boundaries of the unit to minimize reinfection from surrounding  stands. Fire can effectively limit spread of dwarf mistletoe by  eliminating sources of infection and establishing vast acreages of dwarf  mistletoe-free areas.

    Lodgepole pine is subject to attack by many fungal pathogens (33). These  fungi are responsible for reduced growth and considerable cull and  mortality. They also contribute in no small measure to the large amounts  of logging residues that commonly occur when lodgepole pine is harvested.

    One of the most serious diseases in lodgepole pine is a stem canker  caused by Atropellis piniphila. Cankered stems are usually useless  for lumber or posts and poles. Stem cankers of rust fungi cause extensive  mortality, growth loss, and cull in lodgepole pine. Of these comandra  blister rust (Cronartium comandrae) isthe most serious.  The western gall rust (Peridermium harknessii) is especially  damaging; trunk cankers can cause cull in logs and can kill seedlings and  saplings. Because this rust does not require an alternate host, it can  directly reinfect pines. Other fungi attack lodgepole pine and may cause  serious losses in wood production. Examples are needle casts (such as Elytroderma  deformans and Lophodermella concolor); root rots (such as Armillaria  mellea and Heterobasidion annosum); and wood decays (such as  Phellinus pini and Peniophora pseudo-pini).

    Seed and seedling diseases are not usually damaging, although locally  several mold fungi are associated with seed losses in germination, and  rotting and damping-off can affect young seedlings.

    Because of its relatively thin bark, lodgepole pine is more susceptible  to fire than Douglas-fir and many other associates. It is less susceptible  than Engelmann spruce or subalpine fir. Mortality from beetle epidemics  often creates large amounts of jackstrawed fuel, which ignites easily from  lightning and other sources and hampers fire control efforts.

    Chinook winds following extremely cold weather occasionally cause red  belt injury, particularly in Canada and Montana. Defoliation of trees is  common and mortality can occur over large areas. Heavy snow can break or  bend trees, particularly in dense stands with narrow crowns and intense  root competition. Thinning can contribute to snow breakage, particularly  if previously dense stands are opened suddenly.

    Animals can cause considerable damage in thinned stands in some areas.  Porcupines were attracted to thinned and fertilized stands in Montana.  Pocket gophers often cover small seedlings under their entrance mounds and  "winter-casts." They also feed on or clip both roots and tops.  Gopher populations often explode as vegetation increases in open areas.

Lodgepole pine is very intolerant of  shade and competition from other plant species. Occasionally seedlings  become established under a forest canopy, but these individuals rarely do  well. In spite of its shade intolerance, lodgepole pine maintains itself  in dense stands for long periods, often for 100 years or more.

    In the absence of fire, lodgepole pine is usually succeeded by its more  tolerant associates, such as Engelmann spruce and subalpine fir.  Succession proceeds at variable rates, however, and is particularly slow  in some high elevation forests.

    Pure stands of lodgepole pine persist for varying lengths of time. In  northern Idaho and central Oregon, stands begin to break up at 80 to 100  years, while stands at higher elevations, such as in Montana, southern  Idaho, Utah, and Wyoming, last for several hundred years. Pure stands in  and around Yellowstone National Park contain 300- to 400-year-old trees,  with several groups of younger even-aged trees. These stands no doubt  originated as even-aged stands but have been breaking up for more than two  centuries.

    The ability of lodgepole pine to regenerate at the expense of other  species is due not only to cone serotiny but also to seed viability,  germinative energy, early rapid growth, and ability to survive a wide  variety of microsite and soil situations (39).

    Compared to its associates, lodgepole pine is intermediate in its needs  for water, requiring more than Douglas-fir and ponderosa pine and less  than Engelmann spruce and subalpine fir. On some sites, lodgepole pine  appears to compete well for water, however, and grows where other species  may be excluded because of lack of water (45,57); on others it appears to  be tolerant of high water tables (14,43). It is also intermediate in its  tolerance to extremes of temperature (27).

    Lodgepole pine shows good response to thinning at an early age (17).  Heavily stocked stands must be thinned before stagnation occurs. The best  age for thinning varies with site and density. Poor sites and overstocked  stands particularly must be thinned as early as age 10.

    Diameter growth acceleration is usually greatest in heavy thinnings;  cubic volume and basal area growth are usually greatest in light thinnings  (27). Although mechanical thinning, as with bulldozer strips, is a  convenient alternative, obtaining a proper response (36) is difficult.

    At older ages, growth response is strongly correlated with crown size,  vigor, and amount of release provided (27). Attempts at partial cutting of  mature and over-mature stands have resulted in little gain or even  negative net volume growth (1,28).

    Lodgepole pine can be maintained best in a vigorous, productive forest  by using a silvicultural method that regenerates even-aged stands (38).  This often may be accomplished by clearcutting and by relying upon natural  regeneration or planting. Planting provides an excellent opportunity for  initial stocking control and/or genetic improvement.

The root system of lodgepole pine varies  considerably in form, depending on soil type. Root growth is particularly  important during the critical first year. Root growth of 12.7 to 15.2 cm  (5 to 6 in) was reported for seedlings growing on prepared seedbeds in  Montana and Idaho (34). First-season seedlings had an average root depth  of only 9.6 cm (3.8 in) on scarified, unshaded seedbeds in the central  Rocky Mountains (47). Seedlings growing near grass competition usually do  not penetrate beyond 5 or 6 cm (about 2 in).

    Taproots and vertical sinkers are common, but where a hardpan or water  table is encountered, the taproot may die, bend, or assume a horizontal  position. Planting may affect root configuration. Taproots of seedlings  planted with "J-roots" often grow horizontally for many years  before sinkers develop.

    Because of its shallow root system, lodgepole pine is susceptible to  windfall, particularly after stands are opened by harvesting. Windfirmness  varies with stand density, soil conditions, and topography. Shallow roots  are common above hardpan or in shallow, rocky soils.

Lodgepole pine can be grafted  successfully, but results vary depending upon the clone (20). Natural  sprouting has been observed on the Bitterroot National Forest in Montana.  Branches not severed often become leaders on stumps left in thinning  operations.

    Lodgepole pine cuttings are relatively easy to root. Adventitious roots  have been developed artificially from 8-year-old lodgepole pine (by  air-layering) after treatment with either indole-acetic or indole-butyric  acid (17).

    Callus tissue cultures and liquid cell suspensions have been produced  from seedling hypocotyl tissue, excised embryos, and actively growing  shoots.

Germination under field conditions is good  if climate and seedbed are favorable. Best germination occurs in full  sunlight and on bare mineral soil or disturbed duff, free of competing  vegetation. Germination is epigeal. Temperatures fluctuating between 8°  and 26° C (47° and 78° F) favor germination. Adequate soil  moisture is required for germination and survival during the critical few  weeks following germination (34,51,55). In southwest Montana and southeast  Idaho, 75 to 90 percent of a season's total germination occurred during  the 2 weeks following snowmelt in late June (34), when the soil was  saturated and temperatures were favorable. Germination can be delayed if  cones do not open during the previous summer.

    Although lodgepole pine germinates well on most organic seedbeds, such  materials tend to dry faster than mineral soil and seedlings often die in  this seedbed. Lodgepole pine seeds have little need for stratification and  germination depends largely upon temperature (20). At optimum temperatures  and moisture, almost 100 percent of the seeds germinate rapidly.

    Both shading and competition inhibit germination and survival. Newly  germinated seedlings are relatively insensitive to temperature extremes.  Because residual overstory following partial cutting usually does not  provide the most favorable conditions for regeneration, clearcutting is  generally recommended. On some areas, however, lodgepole pine has  established itself in the shade of lightly cut or uneven-aged stands and  may persist for many years in the understory. Some of these trees  eventually may establish a crown sufficient to permit reasonable growth.

    Drought is a common cause of mortality among first-year seedlings;  losses vary with soil type and seedbed condition. Greatest losses occur on  soils with low water-holding capacity, and duff and litter. Well  decomposed organic material, incorporated in the soil, enhances seedling  survival, however. Disturbed mineral soil seedbeds generally produce the  best germination and survival (34,40,41). Shading has been demonstrated to  help under drought conditions in Wyoming (10).

    Drought losses usually decline considerably after the first growing  season. First-year seedlings are particularly vulnerable because of a  relatively shallow root system (34,47).

    Young, succulent seedlings may die because of high soil surface  temperatures (13). By 2 to 4 weeks of age, seedlings are able to withstand  soil surface temperatures higher than 60° C (140° F), which  commonly occur at high elevation sites. Freezing temperatures may kill  seedlings either directly or by frost heaving. In much of the range of  lodgepole pine, however, frosts occur regularly throughout the growing  season and seedlings from different sources vary in frost resistance (16).  The amount of frost heaving varies considerably by soil type, location,  and year of occurrence but can cause significant losses.

    Lodgepole pine seedlings are poor competitors and competition from grass  is often most detrimental. The Douglas-fir/pinegrass habitat type is one  of the most difficult sites for lodgepole pine regeneration, particularly  if the regeneration effort is delayed until a firm sod cover is  established.

    Grazing animals, particularly cattle, can cause seedling mortality by  trampling. Sheep actually seek the succulent new "candles" in  the spring and nibble needles and small branches if other feed is not  abundant.

    A common problem of regenerating lodgepole pine stands is overstocking,  which results in stagnation at early ages. Many sites are stocked with  tens of thousands and even hundreds of thousands of trees per hectare.

    If trees are well distributed, stocking should not exceed 1,240 to 1,980  stems per hectare (500 to 800/acre) between 5 years and 20 years of age  (17). Proper distribution and full utilization of the site, however, may  require establishment of 2,470/ha (1,000/acre) and thinning to obtain  proper spacing. There is also potential for significant genetic gains from  selection of elite trees when thinning.

    An average height of 3.6 m (12 ft) and d.b.h. of 5 cm (2 in) on fully  stocked 20-year-old stands was found on above average sites in Montana  (27). Average heights of 2.0 m (6.7 ft), 4.2 m (13.8 ft), and 7.6 m (24.9  ft) were found on low, medium, and high sites in 20-year-old stands in the  Foothills Section of Alberta (for density class 1,240 stems per hectare or  500/acre at 70 years of age) (32).

    Lodgepole pine height growth begins earlier than any of its associates  except other pines and larch (53).

Lodgepole pine produces  viable seed at an early age, commonly 5 to 10 years; germination  percentage is as high as that of seed borne by mature trees. Pollen  flowers have been observed on 2-0 seedlings in the Lucky Peak Nursery near  Boise, ID.

    Lodgepole pine is a prolific seed producer. Good crops can be expected  at 1- to 3-year intervals, with light crops intervening. The cones  withstand below freezing temperatures and are not generally affected by  cone- and seed-feeding insects. Only squirrels and coreid bugs are  significant seed predators. Seed production should not be taken for  granted, however. Complete seed crop failures have occurred at 2800 m  (9,200 ft) in northwest Wyoming for 2 to 4 years in a row (42).

    Cone production of individual dominant and codominant trees can vary  from a few hundred to a few thousand per tree (37). Cones are persistent,  and serotinous (closed) cones accumulate for decades. Annual production  may run from 173,000 to 790,000 seeds per hectare (70,000 to 320,000/acre)  with half to one-third available for annual seedfall (27). An annual  seedfall of 99,000 to 222,000 seeds per hectare (40,000 to 90,000/acre)  was found in central Montana (58). These figures might be considered  typical for interior lodgepole pine where some portion of the trees are of  the serotinous type. In Oregon, where the nonserotinous cone habit is  prevalent, seedfall ranged from about 35,000 to over 1.2 million/ha  (14,000 to 500,000/acre) (21). Most years seedfall was on the order of  hundreds of thousands per hectare. Where stored seeds are in the millions  per hectare (in closed cones), the number of seeds stored is probably 10  times that of seeds produced annually (37).

    Although the number of fully developed seeds per cone varies from as few  as 1 to 2 to as many as 50, a normal average for large cone lots in the  Rocky Mountains is from 10 to 24 seeds per cone (42). Sierra Nevada  populations range from 5 to 37 seeds per cone (20).

    The serotinous cone habit varies over wide geographic areas as well as  locally (37). Serotinous cones are not common in eastern Oregon, rare in  coastal populations, and absent in the Sierra Nevada and southern  California and Baja California populations (20). Although common in the  Rocky Mountains, this cone habit varies considerably (37). Many stands in  the Rockies have less than 50 percent serotinous-cone trees.

    Lodgepole pine has long been regarded as a fire-maintained subclimax  type. Its ability to regenerate in extremely dense stands to the exclusion  of other species can be attributed to the closed cone habit. Millions of  seeds per hectare are held in reserve for many years and are readily  available to germinate on the seedbed prepared by fire. Recent evidence  seems to indicate that fire selects strongly for the closed cone habit  (49).

    Serotinous cones do not open at maturity because of a resinous bond  between the cone scales. The bonds break with temperatures between 45°  and 60° C (113° to 140° F) (48), and cone scales are then  free to open hygroscopically. Large quantities of seeds are thus available  for regenerating a stand following fire. Closed cones at or near the soil  surface (less than 30 cm or about 12 in) are also subjected to  temperatures from insolation sufficient to open them and may provide seed  in harvested areas. Some seeds may be damaged by fire, however,  particularly in fires burning in logging slash.

    Seeds stored in serotinous cones on the tree remain viable for years.  Apparently, prolonged viability can be maintained so long as cones or  seeds are not in contact with the ground. Once cones are on the ground,  cones open. Damping-off fungi may infect the seed, rodents may feed on the  seeds, or germination may occur; for the most part, seeds are not stored  in the soil.

    Lodgepole pine has relatively small seeds for pine. Seed weights vary  considerably, ranging from 2.3 mg (0.04 grains) per seed in the Interior  of Canada to 11.4 mg (0.18 grains) per seed in the Sierra Nevada (20).  Lodgepole pine seeds average about 298,000 cleaned seeds per kilogram  (135,000/lb) for varieties contorta, 258,000/kg (117,000/lb) for  murrayana, and 207,000/kg (94,000/lb) for latifolia (54).  Density of seedfall 20 m (66 ft) from the timber edge is only 10 to 30  percent of that at the timber edge for stands in the Rocky Mountains (fig.  1) (42). Dispersal of sufficient seed to adequately restock an area often  is only about 60 m (200 ft) (23,38). Prevailing winds, thermal effects, or  scudding on the snow may disperse seeds far beyond these distances,  however.

     
Figure 1- Sound seed per hectare as a function of  distance 
from the nearest timber edge.

    The annual seedfall from nonserotinous cones helps in restocking  relatively minor disturbances in the stand, in maintaining the presence of  lodgepole pine in mixed stands, and in expanding conifers into other  vegetative types. Seldom do we find stands without some trees of the  open-coned type. The efficacy of this seed source can be seen in the dense  stands of lodgepole pine along road cuts, powerline rights-of-way, and  ditches or where disturbance occurs near lodgepole pine stands.

    Studies of seedfall have shown variation in the number of seeds released  soon after cone maturation, but most seeds (80 to 90 percent) are released  before the following growing season (27).

    Where large amounts of seed are stored in serotinous cones, a most  effective means of seed dispersal in clearcuts is from cones attached to  the slash and those knocked from the slash and scattered over the forest  floor during slash disposal. Many cones on or near the ground are opened  by normal summer soil surface temperatures (35). In Montana 83 percent of  the cones on the ground opened the first year on south slopes compared to  40 percent on north slopes. Maximum seed release from serotinous cones  near the ground takes place during the first year of exposure. In fact,  cones may open after the first few minutes of exposure to temperatures  high enough to break the resinous bonds.

    In slash, serotinous cones that are well above the ground behave like  those on a tree- they remain closed, and stored seeds remain viable for  years.

    Seeds in unopened cones and those released from the slash may also be  lost to rodents, fungi, and other destructive agents. Seeds from closed  cones are usually available only for the first growing season following  harvest, but stocking from open-cone seed sources can continue to increase  for several years.

    Slash disposal on areas where regeneration is planned from serotinous  cones must be carefully planned and executed. Seed supply will be largely  destroyed if slash to be burned is piled before cones have had a chance to  open (38). Piling slash should be delayed until sufficient cones have  opened to assure adequate stocking. Piling then scatters seeds and opened  cones and helps prepare the seedbed. Piling slash after germination can  also decrease stocking because young seedlings are trampled or buried.

    Broadcast burning may hasten release of seeds from cones not in a  position to open from high soil-surface temperatures. Some seeds will be  destroyed, however; the amount will vary with fire intensity.

Male and female strobili generally are  home separately on the same tree in this monoecious species, with female  flowers most often at the apical end of main branches in the upper crown,  and male flowers on older lateral branches of the lower crown. The reddish  purple female flowers grow in whorls of two to five and are 10 to 12 mm  (0.4 to 0.5 in) long. The pale yellow to yellowish orange male flowers are  crowded clusters of catkins at the base of new shoots and are 8 to 14 mm  (0.3 to 0.6 in) long. It is not uncommon to find a dominance of maleness  or femaleness on individual trees.

    Pollen generally matures in mid-May to mid-July (table 1) (20,52). The  time at which pollen matures appears to be related to elevation and  climate.

    Table 1- Time of pollen shedding in natural stands of  lodgepole pine (20,52, modified)           
Stand location   
Elevation¹  Years observed  Date of peak shedding              m  ft          Vancouver, BC  -  -  2  Middle to late May      Northwestern Washington  150  500  10  May 12      Mendocino White Plains, California  -  -  1  June 9      Northern Cascades  1200  4,000  -  Mid-June      Northern Idaho; western Montana  -  -  10  June 13      Central and eastern Washington and Oregon  790 to 1300  2,600 to 4,250  -  June 13      Southeastern Alberta (subalpine forest)  -  -  10  June 22      Sierra Nevada, California  1820  6,000  3  June 22      Central Montana; Yellowstone region  -  -  10  June 25      Northern Utah  2190  7,200  2  July 12      Southern Idaho  2070  6,800  1  July 7      Northern Idaho; western Montana  670 to 1265  2,200 to 4,150  10  June 6      Eastside Montana; Yellowstone National Park  975 to 2060  3,200 to 6,750  10  June 17      ¹Dash indicates  data are not available.        Seed cones usually mature in August, September, or October, more than a  year after pollination. Inland forms and high elevation stands apparently  mature earlier than coastal forms or low elevation stands. Cones open in  early September in the Northern Rocky Mountains. Cone maturity is  indicated by a change in color from purple-green to light brown (54).

Growth and yield of lodgepole pine is greatly  affected by stand density (31) as well as by environmental factors  (2,6,22,46). In fact, site index curves have been developed with  corrections for effects of stand density.

    Maximum yield in the Rocky Mountains was 280 m³/ha (20,000  fbm/acre) at a density of 1,980 trees per hectare (800/acre), but only 21  m³/ha (1,500 fbm/acre) at a density of 4,450/ha (1,800/acre),  assuming 5 fbm/ft³; original figures were in board feet (27).

    In extreme cases 70-year-old stands with 247,000 trees/ha (100,000  trees/acre) averaged only 1.2 m (4 ft) in height and less than 2.5 cm (1  in) in diameter at ground level.

    Yields of 168 to 224 m³/ha (about 12,000 to 16,000 fbm/acre) can be  found in old-growth Rocky Mountain lodgepole pine. Yields of more than 336  m³/ha (about 24,000 fbm/acre) are the result of a fortuitous  combination of favorable initial stocking, good site quality, and absence  of mountain pine beetle and dwarf mistletoe.

    Relationships among age, stocking levels, and development in natural  stands were summarized for medium sites in Montana and Idaho (site index  22.9 m or 75 ft at 100 years) (table 2). Under light to moderate stocking,  live crowns are 25 to 60 percent of total height.

    Table 2- Relationships among stand age and stocking  level, and tree development and typical yield in natural stands of  lodgepole pine, summarized for medium sites in Montana and Idaho (site  index 22.9 m or 75 ft at base age of 100 years)¹           
Age   
Stocking  Average height of dominants  Average stand diameter   
Total cubic volume   
Merchantable volume            yr  trees/ha  trees/acre  m  ft  cm  in  m³/ha  ft³/acre  m³/ha  ft³/acre  fbm/acre        20    1,240     500    5.5  18    8.6    3.4    16.1     230  -            19,770  8,000    3.0  10    4.1    1.6    28.0     400  -            50    1,180     479  12.5  41  16.5   6.5  144.9  2,070  130.2  1,860    5,100        15,200  6,150    9.1  30    6.9    2.7  165.9  2,370  -  -  -        80    1,030     418  18.0  59  20.6    8.1  285.6  4,080  266.0  3,800  12,100          7,500  3,034  14.6  48    9.1    3.6  280.0  4,000  -  -  -      110       850     344  22.3  73  23.6    9.3  385.7  5,510  363.3  5,190  18,200          4,600  1,861  18.9  62  11.4    4.5  357.0  5,100  273.0  3,900    8,400      140       680     275  25.3  83  26.7  10.5  448.7  6,140  426.3  6,090  23,200          3,070  1,243  22.3  73  14.0    5.5  416.5  5,950  301.0  4,300  10,300      ¹Compiled from unpublished  yield tables furnished by D.M. Cole, USDA Forest Service, Intermountain  Research Station, Bozeman, MT. Cubic volumes are from trees 11.4 cm (4.5  in) in d.b.h. to a 7.6 cm (3 in) diameter top. Board foot volumes are  from trees larger than 16.5 cm (6.5 in) in d.b.h. to a 15.2 cm (6 in)  diameter top.        Mature sizes vary greatly between stands. In the Rocky Mountains, most  trees at 140 years of age were 18 to 33 cm (about 7 to 13 in) in d.b.h.  and 18 to 25 m (about 60 to 80 ft) in height (27).

    Trees in the Blue Mountains of Oregon average 30 cm (about 12 in) in  d.b.h. and 23 m (about 75 ft) tall at 100 years of age. Sierra Nevada  trees the same age are larger, averaging 42 cm (about 16 to 17 in) in  d.b.h. and 28 to 30 m (about 90 to 100 ft) tall. Coastal trees are smaller  but vary greatly. Mature trees range from 15 to 50 cm (about 6 to 20 in)  in d.b.h. and only 6 to 12 m (20 to 40 ft) tall. Dwarf lodgepole pines are  only about a meter (2 to 5 ft) tall and are found along the coast in  Mendocino County, CA. This small size is thought to be caused by a highly  acid hardpan.

    Growth of lodgepole pine is often so stagnant that stand culture is not  practical. Early management and control of stocking greatly affects growth  and yield of lodgepole pine stands (17). Average annual growth in  old-growth unmanaged stands in the central Rocky Mountains only was 0.4 to  0.6 m³/ha (about 25 to 40 fbm/acre) because of large numbers of small  trees and a high incidence of dwarf mistletoe (4). (Calculations assume 5  fbm/ft³; original figures were in board feet). Annual net growth may  be increased to 2.1 to 5.6 m³/ha (about 150 to 400 fbm/acre) by  controlling stand density and reducing dwarf mistletoe infection (5,25).

    Control of stand density offers the greatest opportunity for increasing  productivity of any readily available management practice.

    Culmination of total cubic volume occurs as early as 40 years in  severely stagnated stands, and between 50 and 80 years for overstocked,  but not greatly stagnated, stands. Merchantable volume culmination in  stands of the latter type occurs between 110 and 140 years, depending on  merchantability standards.

    Thinning of young overstocked and stagnating stands can restore growth  potential and redirect it into merchantable-size products. With more  complete utilization (lower merchantable d.b.h. and top diameters), most  of the yield increase possible from thinning is attained with the first  entry, a stocking control thinning (17).

This summary is based on a recent review of the literature on the  genetics of lodgepole pine (20). The ability of some strains of lodgepole  pine to grow well on poor sites and in cold climates has interested  European foresters for many years. Much of what is known about the genetic  diversity of the species has been learned from provenance tests, mostly in  northwestern Europe. These tests have established that much of the  variation observed in natural stands of lodgepole pine has a genetic  basis.

The following is a representative barcode sequence, the centroid of all available sequences for this species.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 8
Specimens with Barcodes: 17
Species With Barcodes: 1

Year Assessed

• Needs updating

Assessor/s

Reviewer/s

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Reasons: Extensive range from Alaska to northern New Mexico and Baja California, attaining best populations in the Rocky Montains (Record and Hess 1943). Thrives in mostly well drained soils but may be found in peat bogs, muskegs or on dry sandy sites. Successfully cultivated in New Zealand and the United Kingdom (Tree Talk 1994).

Comments: The timber is well known (Tree Talk 1994).

Lodgepole pine is not only an important timber species but is also a  major tree cover in many scenic and recreational areas and on critical  watersheds. It provides many acres of wildlife habitat and is associated  with many grazing allotments throughout its range. It is important to  local communities throughout the West.

    Lodgepole pine is used for framing, paneling, posts, corral poles,  utility poles, railroad ties, and pulpwood. As new developments such as  structural particleboard become practical, the rapid juvenile growth of  the species will be an advantage where gross cubic volume becomes  important. Even now, with properly designed machinery, it is economically  harvested, and this harvesting, properly done, can enhance watershed,  forage, wildlife habitat, and scenic and recreational values.

Comments: Uses of the timber are local for mining timbers and railway crossties, sometimes under the name of Tamarack (Record and Hess 1943). Other common applications are corral rails, veneer, hardboards, mine timbers, orchard props, paneling, particleboard, plywood, poles, posts, pulpwood, rough construction, rustic furniture, shingles and siding (Tree Talk 1994).