Lodgepole Pine

''Pinus contorta'', with the common names lodgepole pine and shore pine, and also known as twisted pine, and contorta pine, is a common tree in western North America. It is common near the ocean shore and in dry montane forests to the subalpine, but is rare in lowland rain forests. Like all pines (member species of the genus ''Pinus''), it is an evergreen conifer.

Description

Depending on subspecies, ''Pinus contorta'' grows as an evergreen shrub or tree. The shrub form is krummholz and is approximately high. The thin and narrow-crowned tree can grow high and achieve up to in diameter at chest height. The ''murrayana'' subspecies is the tallest. The crown is rounded and the top of the tree is flattened. In dense forests, the tree has a slim, conical crown. The formation of twin trees is common in some populations in British Columbia. The elastic branches stand upright or overhang and are difficult to break. The branches are covered with short shoots that are easy to remove.

The species name is ''contorta'' because of the twisted, bent pines found at coastal areas (shore pine) and the tree's twisted needles. ''Pinus contorta'' is occasionally known under several English names: black pine, scrub pine, and coast pine. ''P. contorta'' subsp. ''latifolia'' will hybridise with the closely related jack pine (''P. banksiana'').

The bark of lodgepole pine is thin, scaly and grayish brown. Shore pine bark is somewhat thick and corky, fissuring into a checkered pattern. Some lodgepole pines have been reported in low elevations with features closer to those of the shore pine, including the bark.

Tamarack pine can grow up to centuries old and lodgepole pines in Yellowstone Park have survived over 300 years.

Foliage

The egg-shaped growth buds are reddish-brown and between long. They are short pointed, slightly rotated, and very resinous. Spring growth starts in beginning of April and the annual growth is completed by early July. The dark and mostly shiny needles are pointed and long and wide. The needle edge is weakly to strongly serrated. The needles are in pairs on short shoots and rotated about the shoots' longitudinal axes. In Alberta above , 1 to 5 needles occur per short shoot. A population with a high proportion of three-needled short shoots occurs in the Yukon. Needles live an average of four to six years, with a maximum of 13 years. The foliage of lodgepole pine is yellow-green as compared to shore pine, which is dark green.

Cones

The cones of lodgepole and shore pine begin to be produced when the trees are about ten years old. The cones are long, with prickles on the scales.

Many populations of the Rocky Mountain subspecies, ''P. contorta'' subsp. ''latifolia'', have serotinous cones. This means that the cones are closed and must be exposed to high temperatures, such as from forest fires, in order to open and release their seeds. The variation in their serotiny has been correlated with wildfires and mountain pine beetle attacks. The cones of the coastal Pacific subspecies, ''P. contorta'' subsp. ''contorta'', are typically non-serotinous, and those of the inland Pacific subspecies, ''P. contorta'' subsp. ''murrayana'', are completely non-serotinous.

Distribution

''Pinus contorta'' occurs from upper, dry montane forests to the subalpine region of western North America. It can be found on the western side of the Cascades, in inland British Columbia, and on the Rocky Mountains in Alberta, except where it is too high and dry. Lodgepole pine can tolerate relatively hostile environments such as high-elevation volcanic rock in Central Oregon (e.g. Crater Lake) and thin soils on the eastern slope of the Cascades. Further south, the species can be found in higher elevations up to above sea level, particularly in southern Colorado. It is rare in lowland rain forests. Shore pine can be found in very infertile soils in coastal regions from Southeast Alaska to Northern California.

Lodgepole and shore pine can be found intermingled (and apparently hybridized) north of Puget Sound. Less dependent on fire, tamarack pine can be found in California's upper mountains and mingled with lodgepole in Oregon. ''Pinus contorta'' can be found in the closed-cone pine forest of coastal California.

Ecology

''Pinus contorta'' is a fire-dependent species, requiring wildfires to maintain healthy populations of diverse ages. The thin bark of the lodgepole pine minimizes its defense to fire, although the heat of fire opens the cones to release the seeds. This allows the species to regenerate and maintain its place in the forest habitat. It otherwise fares poorly in crowds as other species are more shade tolerant, although some (e.g. firs) are more susceptible to fire.

The natural fire regime for this species is primarily driven by climate. The fires occur most often after years of drought. Forests in the upper montane to subalpine region experience much moisture in the winter via snow. The density of tree stands with the species inhibit the establishment of an understory (allowing ladder fuel

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