Lodgepole pine

Appearance

Depending on subspecies, ''Pinus contorta'' grows as an evergreen shrub or tree. The shrub form is krummholz and is approximately 1 to 3 metres high. The thin and narrow-crowned tree is 40 to 50 metres high and can achieve up to 2 metres 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's 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 ''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''.

Naming

There are four subspecies of ''Pinus contorta'', one of them sometimes considered to have two varieties. The subspecies are sometimes treated at the rank of variety.

⤷ ''Pinus contorta'' subsp. ''bolanderi'' — Bolander's beach pine, Bolander pine; endemic to NW California Coast ; Near Threatened by fires, and development. )
⤷ ''Pinus contorta'' subsp. ''contorta'' — Shore pine; Pacific Coast, southern Alaska to California. )
⤷ *''Pinus contorta'' subsp. ''contorta'' var. ''contorta'' — Shore pine; Pacific Coast, Northwest California through Alaska.)
⤷ ''Pinus contorta'' subsp. ''murrayana'' — Tamarack pine, or Sierra lodgepole pine; Cascade Ranges from Washington into Northern California, the Sierra Nevada, the Transverse Ranges of Southern California , the Peninsular Ranges into northern Baja California, and the Spring Mountains of southern Nevada.
⤷ ''Pinus contorta'' subsp. ''latifolia'' — Lodgepole pine; Rocky Mountains, Colorado to Yukon and Saskatchewan; Aspen parkland and boreal forests.''Pinus contorta'' is a serious invasive species of wilding conifer in New Zealand, along with several other western North American pine species. It is listed on the National Pest Plant Accord and is prohibited from sale, commercial propagation, and distribution.

Habitat

''Pinus contorta'' is a fire dependent species, requiring wildfires to maintain healthy populations of diverse ages. The bark of the lodgepole pine is fairly thin, minimizing the defense the tree has to fire. The heat of these closed-cone pine forest rejuvenating fires open the cones to releasing the seeds. This allows the species to regenerate and maintain its place in the forest habitat.

Excessive wildfire prevention disrupts the fire ecology. The stands are usually so densely populated that the trees self thin, or out-compete each other, leaving dead trees standing. These become a dry ladder fuel that can accelerate the fire to the crown of living trees. When the fire reaches the crowns of the trees, it can jump from tree to tree and becomes relatively unstoppable.

The natural 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.

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 , 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.

''Suillus tomentosus'', a fungus, produces specialized structures called tuberculate ectomycorrhizae with the roots of lodgepole pine . These structures have been shown to be the location of concentrations of nitrogen fixing bacteria which contribute a significant amount of nitrogen to tree growth and allow the pines to colonize nutrient-poor sites.

Predators

This species is attacked by Blue stain fungus , distributed by the Mountain Pine Beetle from its mouth.

A recent study estimates that ''Pinus contorta'' could experience significant reductions of its distribution range due to climate change by the late 21st century.