Different species of trees grow in different places, depending on soil type, temperature, rainfall and other factors. Trees also grow in association with other species that have the same growing requirements. These associations of trees and plants are called 'forest types'. Thunder Bay is in a transition zone between two forest types: the boreal forest and the Great Lakes-St. Lawrence forest.
The boreal forest is the predominant type in northern latitudes. It stretches from coast to coast across Canada south of the Arctic tundra. The tree species are adapted to regenerate quickly after forest fires. The main conifer species are black and white spruce, jackpine, balsam fir, larch (tamarack) and cedar; the dominant hardwood species are trembling aspen, balsam poplar and white birch.
Black spruce tends to grow in "pure" stands on boggy sites rich in organic material call peat. Because its long fibres make high quality paper, much of the black spruce in the surrounding forests has been logged. Black spruce forests are the primary habitat for pine marten and woodland caribou. The distribution of caribou has decreased as logging has destroyed much of their habitat. Although similar in appearance to black spruce, white spruce grows on well-drained sites in mixed stands. This species is useful for structural timber because it grows to a relatively large diameter.
Jackpine prefers well-drained sandy sites where its long taproot can penetrate deep into the soil for moisture. Jackpine is used in paper manufacturing and sawmills. The cones are sealed shut with a resinous substance which opens only under high heat. Jack pine forests are easy to replant from seedlings.
The balsam fir is probably best known as Canada's traditional Christmas tree. Because balsam fir grows in a variety of sites in the boreal forest and is tolerant of shade, it tends to colonize areas after disturbances such as clear cutting. Consequently, the proportion of balsam fir has increased in the forests of northwestern Ontario.
Cedar and larch are both found scattered throughout the boreal forest in wetland sites. Cedar is very long-lived and easily recognized by its distinctive flat foliage. Cedar is an important source of food and shelter for wildlife; birds enjoy cedar seeds and deer seek out upland cedar stands for shelter and browse. The larch, not an abundant species, is a unique conifer because it loses all of its needles each autumn.
There are only three main deciduous species in the boreal forest: trembling aspen and balsam poplar (both species of poplar) and white birch. Much of the forest in the region is now trembling aspen. Called a "pioneer species" because it is first to recolonize a disturbed area, its triangular leaves with flat stems quiver in the wind. Trembling aspen reproduces from root suckers when the main trunk is cut, so it is very difficult to eradicate once it is established. It has become an important species for forest companies because it can be harvested and chipped to make prefabricated building boards known as oriented strand board.
Balsam poplar is also known as the "Balm of Gilead". The long pointed buds produce a sticky resinous substance. Also a pioneer species, it relies on the wind to carry its light fluffy seed great distances. Both aspen and balsam poplar are commonly found in mixed stands, often growing with white spruce, white birch and balsam fir.
White birch is one of the best known species growing in the boreal forest, although it is one of the least abundant. It is also called paper birch because of the papery bark which peels off in layers. Birch makes excellent firewood because it is very dense. Because birch is not of primary economic importance, it is often the only species left standing when forests are clear-cut; however, birch can be utilized for veneer and specialty products.
Thunder Bay also boasts many tree species from the Great Lakes-St. Lawrence forest, especially to the west and south along the border. White pine, Ontario's provincial tree, is perhaps the best known conifer in this forest type. Majestic and long-lived (up to 500 years), white pine soars above the other trees in the forest. It is much sought after by sawmills because of the high volume of quality wood produced by a single tree. White pine was found as stands, major pockets and scattered clumps in a line from Sioux Lookout to Lake Nipigon then south to Lake Superior. White pine is now restricted to parks and areas protected from harvesting, such as Greenwood Lake. Present forestry practice does not encourage regeneration of the once abundant species in this region. Red pine is often found in association with white pine. White pine has greyish bark and five needles clustered together, whereas red pine has red bark and three very long needles.
Several other tree species of the Great Lakes-St. Lawrence type can be found in unusual sites around Thunder Bay where special growing conditions offer shelter from the harsh northern winters. The Nor'westers are home to red and sugar maples, as well as yellow birch.
Click here for more information about the flora and fauna of Northwestern Ontario's boreal forest.
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