The boreal forest is Canada’s largest vegetation zone, making up 55 per cent of the country’s land mass. It extends from the Yukon and northern British Columbia in the west to Newfoundland and Labrador in the east.
The boreal forest is Canada’s largest vegetation zone, making up 55 per cent of the country’s land mass. It extends from the Yukon and northern British Columbia in the west to Newfoundland and Labrador in the east. Although the zone includes varied terrain, including lakes and wetlands, the majority of the region is dominated by trees. The area houses a diverse group of wildlife, and is crucial to maintaining biological diversity, storing carbon, purifying air and water, and regulating the climate. With over 2.5 million Canadians living in the boreal zone, the forest also provides these rural communities with jobs and economic stability.
Bordered to the north by treeless arctic tundra and to the south by temperate forest or grassland, the zone includes three ecologically distinct subzones: the northern boreal woodland, the main boreal forest, and the southern boreal forest. The northern woodland is characterized by widely spaced coniferous trees, hardy low shrubs, and sun-loving lichens. The main boreal forest includes closely spaced evergreen and deciduous trees, as well as shade-tolerant shrubs with herbs and feathermoss carpets beneath them. Finally, the southern part of the region is similar to the main forest but contains the occasional temperate deciduous tree and other plant species. The evergreen trees that dominate the region are black and white spruce, jack and lodgepole pine, and balsam fir, while the deciduous trees include American larch, paper birch, trembling aspen, and balsam poplar.
There are also two transitional subzones: hemi-arctic forest tundra—a mosaic of taiga and tundra vegetation along the northern margin—and mosaics of boreal and temperate vegetation along the southern margin. This southern subzone is defined by hemi-boreal aspen parkland in the west and northern conifer-hardwood forest in the east.
Until 12,000 years ago, most of today’s boreal forest was covered by glaciers. Because of this, much of the region’s topography and surficial geology results from glaciation, and most of its soils are young compared with those in unglaciated areas. In terms of the forest’s boundaries, global warming and cooling have historically caused the area’s north–south limits to shift up or down depending on temperature.
Treed and treeless wetland networks occur in poorly drained areas. They are usually composed of fens, acidic peat bogs, and nutrient-rich marshes underlain by varying amounts of organic material. These marshes are extensive in some regions, such as the Hudson Bay lowlands. Permafrost occurs in small patches in the southern half of the zone, but is virtually continuous over wide areas of the northern half.
The boreal forest experiences more fire than the other, more temperate forests in Canada. Lightning- and human-induced fires burn vast areas of its highly flammable coniferous forest during dry summers, but most of its plant species are adapted to survive fires or to recolonize burn areas quickly. In fact, these fires are crucial to the forest’s existence, as they release nutrients found in waste on the forest floor, open the canopy to sunlight, and allow some plant species to reproduce by opening pinecones and freeing seeds. There is a predictable succession of post-fire vegetation, often beginning with fireweed; passing through an equally short-lived willow stage; a longer open-sun forest stage dominated by aspen, pine or birch; and ending with a shaded, spruce-fir forest, which persists until the next fire. These post-fire successional sequences are frequently interrupted by another fire, and hence the forest returns to the fireweed stage well before the final stage is reached.
Animals and Insects
Prominent mammals in the forest include moose, caribou, black bear, wolf, beaver, muskrat, varying hare, red squirrel, deer mouse, and red-backed vole. The region is also home to half of Canada’s 425 bird species, including Canada goose, common loon, great blue heron, numerous hawks, owls and ducks, ruffed and spruce grouse, belted kingfisher, gray jay, robin and other thrushes, black-capped and boreal chickadees, several nuthatches, vireos and grosbeaks, as well as many species of warblers and sparrows. Justly infamous insects include mosquitoes, black flies, and sand flies.
Some climatologists predict that global warming will force the boreal forest and its associated industries to migrate northward very rapidly in the third millennium, surrendering much of their present range to temperate forest and arid grassland vegetation.
Introduction. The boreal forest (also known as the taiga, a russian word meaning swampy moist forest) is found in a nearly continuous belt across North America and Eurasia. Most of Canada and Russia are covered by coniferous trees that make up this biome. This biome is defined mainly by the trees that compose it. The climax trees are furs, spruces and pines. Subclimax plant communities may have deciduous trees like larch, tamarack and birch. Much of the zone that this biome covers was formerly glaciated. Today large sections have permenent permafrost.
Climate: The boreal forest corresponds with regions of subarctic and cold continental climate. There are long, severe winters (up to six months with mean temperatures below freezing) and short summers (50 to 100 frost-free days), as is a wide range of temperatures between the lows of winter and highs of summer. For example, Northern Minnesota, near the boundry waters where we canoed, has recorded extremes of minus 70 ° Fand plus 100 ° F. Mean annual precipitation is 15 to 20 inches,(55 to 70 inches in the boundry waters) but low evaporation rates make this a humid climate.
Vegetation: This biome has very characteric trees. Dominant trees in the tiaga are Needleleaf, coniferous (gymnosperm) trees. From a biodiversity standpoint, there is little diversity in the main trees. The four main genera found are: the evergreen spruce (Picea), fir (Abies), and pine (Pinus), and the deciduous larch or tamarack (Larix). In North America, one or two species of fir and one or two species of spruce are dominant. Across Scandanavia and western Russia the Scots pine is a common component of the taiga.
There are several other trees that can be found in this zone. They are early succesional trees (trees found in disturbed habitats that over time will be replaced by the climax community of spruce, firs and pines). The most common trees are the deciduous alder (Alnus), birch (Betula), and aspen (Populus).
Growthform Adaptations: The main reasons firs, sprucs and pines are the dominant trees in the boreal forest, and thus define the biome is because they are adapted to the extreme conditions brough about by the cold, including the winter-induced drought and the short growing season. The following are some of the main adaptations we found that trees in this zone have:
- Conical shape - promotes shedding of snow and prevents loss of branches.
- Needleleafs - narrow leaves reduce surface area through which water can be lost (transpired), especially in the winter when the frozen ground prevents plants from replenishing their water supply. The needles of boreal conifers also have thick waxy coatings--a waterproof cuticle--in which stomata are sunken and protected from drying winds.
- Evergreen habit - retention of foliage allows plants to photosynthesize as soon as temperatures permit in spring, rather than having to waste time in the short growing season merely growing leaves. [Note: Deciduous larch are dominant in areas underlain by nearly continuous permafrost and having a climate even too dry and cold for the waxy needles of spruce and fir.]
- Dark color - the dark green of spruce and fir needles helps the foliage absorb maximum heat from the sun and begin photosynthesis as early as possible.
Soil: Podzolization occurs as a result of the acid soil solution produced under needleleaf trees. The main soil order associated with the taiga is spodosol.
Other explanations of boreal forest
Boundary Waters Case Study, Northern Minnesota
In May of 2006, Suzi Serengeti and I decided to take a trip to the Boundary Waters Canoe Wilderness in Northern Minnesota in an effort to discover what boreal forests were all about. If you look at any map of boreal forest you'll notice that the lower extension of this biome dips into Northern Minnesota. We were prepared for the canoe trip, but we were very curious about the biome.
Everywhere we went we read about boreal forests. It said they were in the area, but we still didn't know what it was. As it turns out boreat forests are determined mostly by the trees in the area. Certain parts of the forest were more 'typical' boreal forest than others. Those with more red pine, white pine, spruce and fir, and those in low, boggy areas were the most characteristinc of the biome.
A lot of the Boundary waters is made up of Birch (seen in the picture above), Aspen and Poplars. This is much less typical of the boreal forest, yet it stands as a good transition zone between the forest to the north which have predominantly conifer trees and the deciduous forests to the south.
Text by Rob Nelson
Text is temporary. It is used by the crew in the field to prepare video.