Appearance
''Pinus banksiana'' ranges from 9–22 m in height. Some jack pines are shrub-sized, due to poor growing conditions. They do not usually grow perfectly straight, resulting in an irregular shape similar to pitch pine . This pine often forms pure stands on sandy or rocky soil. It is fire-adapted to stand-replacing fires, with the cones remaining closed for many years, until a forest fire kills the mature trees and opens the cones, reseeding the burnt ground.The leaves are in fascicles of two, needle-like, twisted, slightly yellowish-green, and 2–4 centimetres long.
Jack pine cones are usually 5 centimetres and curved at the tip. The cones are 3–5 cm long, the scales with a small, fragile prickle that usually wears off before maturity, leaving the cones smooth.
Unusually for a pine, the cones normally point forward along the branch, sometimes curling around it. That is an easy way to tell it apart from the similar lodgepole pine in more western areas of North America. The cones on mature trees are serotinous. They open when exposed to intense heat, greater than or equal to 50 °C . The typical case is in a fire, however cones on the lower branches can open when temperatures reach 27 °C due to the heat being reflected off the ground. Additionally, when temperatures reach −46 °C , the cones will open, due to the nature of the resin.
Habitat
Kirtland's warbler , an endangered bird, depends on pure stands of young jack pine in a very limited area in the north of the Lower Peninsula of Michigan for breeding. Mature jack pine forests are usually open, and the fall of their needles creates acidic soil, so blueberries are often abundant in the understory.Young jack pines are an alternate host for sweet fern blister rust . Infected sweet ferns release powdery orange spores in the summer and nearby trees become infected in the fall. Diseased trees show vertical orange cankers on the trunk and galls on the lower branches. The disease does not tend to affect older trees.
Jack pines are also susceptible to scleroderris canker . This disease manifests by yellowing at the base of the needles. Prolonged exposure may lead to eventual death of the tree.
Insects that attack jack pine stands include white pine weevil , jack pine sawfly, and jack pine budworm.
Uses
Like other species of pine, ''Pinus banksiana'' has use as timber, although its wood tends to be knotty and not highly resistant to decay. Products include pulpwood, fuel, decking, and utility poles.References:
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