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Lodgepole Pine, Pinus contorta, also known as Shore Pine, is a common tree in western North America.[2] Like all pines, it is evergreen.
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There are three subspecies of Pinus contorta, one of them with two varieties. All the four taxa are sometimes treated at the rank of variety.[3][4]
Depending on subspecies, the Lodgepole Pine grows as an evergreen shrub or tree. The shrub form is krummholz and is approximately 1 to 3 metres (3.3 to 9.8 ft) high. The thin and narrow-crowned tree is 40 to 50 metres (130 to 160 ft) high and can achieve up to 2 metres (6.6 ft) diameter at chest height.[7] The murrayana subspecies is the tallest. The crown is rounded and the top of the tree is flattened. In dense forests, the trees 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.[8]
The species name contorta arises from the twisted, bent pines found in the coastal area. 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 - Pinus banksiana.
The egg-shaped growth buds are reddish-brown and between 20 and 30 millimetres (0.79 and 1.2 in) 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 4 to 8 centimetres (1.6 to 3.1 in) long and 0.9 to 2 millimetres (0.035 to 0.079 in) wide. The needle edge is weak to clearly serrated. The needles are in pairs on short shoots and rotated about the shoots' longitudinal axes. In Alberta above 2,000 metres (6,600 ft), 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.[8]
The 3–7 cm cones often need exposure to high temperatures (such as from forest fires) in order to open and release their seeds, though in subsp. murrayana they open as soon as they are mature. The cones have prickles on the scales.
The lodgepole is a fire adapted tree. The bark of the lodgepole pine is fairly thin, minimizing the defense the tree has to fire. The way that these stands regenerate is so densely populated that they self thin, or out compete, each other leaving dead trees in the stand. These dead trees often fall and become a dry ladder fuel to accelerate the fire to the crown of the tree. When the fire reaches the crowns of the trees, it can jump from tree to tree and becomes relatively unstoppable. These stand replacing fires are what the lodgepole pine relies on to be able to regenerate in the post burn area[9]
The Pinus contorta as a species is a very dependent on fire as a mode of replacing itself. The fire regime for this species is primarily driven by climate. The fires occur most often after years of drought. Lodgepole Pine occurs from the upper montane to the subalpine region. These types of forests experience a lot of moisture in the form of snow in the winter due to their altitude. The density of the tree stand also prohibits the establishment of an understory. With all of that being said, the likelihood of a surface fire occurring are rare. Thus, infrequent, high severity fires dominate this species.[9]
An example of the climate that plays a huge role in the fire regime of the lodgepole pine is quite complex. There are three different oscillations that play a major role in droughts. These are the Pacific Decadal Oscillation (PDO), Atlantic Multi-decadal Oscillation and El Nino. A combination of these oscillation being in effect (+) or not in effect (-) have a global effect on the water available to these forests. So when the AMO +, ENSO – and PDO -, there is going to be a drought and likely a severe subalpine fire.[10]
Suillus tomentosus, a fungus, produces specialized structures, known as tuberculate ectomycorrhizae, with the roots of lodgepole pine (Pinus contorta var. latifolia). These structures have in turn been shown to host nitrogen fixing bacteria which contribute a significant amount of nitrogen and allow the pines to colonize nutrient-poor sites.[11]
Blue stain fungus, Grosmannia clavigera, attacks this species from the mouth of the Mountain Pine Beetle.
A study in 2011 suggests that by the late 21st century, P. contorta could experience significant reductions to its range due to climate change.[12][13]
Pinus contorta is a serious invasive species wilding conifer, along with several other western North American pine species, in New Zealand. It is listed on the National Pest Plant Accord and is prohibited from sale, commercial propagation and distribution.
Lodgepole pine is named for its common use in the Native American tepee lodge. A typical tepee is constructed with 15-18 lodgepole pines. The long, straight, and lightweight characteristics of the species made it ideal for horse transport in nomadic buffalo hunting cultures. Tribes made long journeys across the plains to secure lodgepole pines that only grew in mountainous areas. In Minnesota, other species such as red pine would be used in tepees, though they were generally thicker, heavier, and more cumbersome to transport than lodgepole pine.
Many people still use lodgepole pine today for erecting tepees at private homes, on Native American reservations, or powwows. The pines may be harvested for tepee poles on National Forests, provided the harvester secures a permit to cut lives trees for ceremonial or traditional purposes. The Bighorn Mountains, the Black Hills, and the Snowy Range of Wyoming are popular tepee pole harvesting areas for tepee enthusiasts and Native Americans living on plains reservations in North and South Dakota.
The Pinus contorta has been planted extensively in Norway and Sweden for use in forestry.
The horticulture industry grows Pinus contorta subsp. contorta and P. contorta subsp. murrayana for gardens and native plants landscapes. The ssp. contorta Shore Pine's smaller selections are also used in 'large bonsai' specimens and container gardening.
Lodgepole Pine is the Provincial tree of Alberta, Canada.