KEY FINDING 1. At a national level, the extent of forests has changed little since 1990; at a regional level, loss of forest extent is significant in some places. The structure of some Canadian forests, including species composition, age classes, and size of intact patches of forest, has changed over longer time frames.
This key finding is divided into five sections:
- Key finding overview (this page)
- Changes in the treeline zone
- Intactness of Canada's landscapes
- Shift from late-succession to early-succession forests
Forests are dynamic and diverse ecosystems, where complex interactions occur between species and ecological processes, from below ground to high in the canopy. Forests are important to biodiversity because they provide habitat for a wide array of plant and animal species from microorganisms to large mammals and because they are a pool of genetic diversity. It is estimated that approximately two–thirds of the species in Canada are associated with forests for at least part of their life cycle.1, 2 Forests also provide ecosystem services, including the regulation of water flow across the landscape, erosion control, water purification, climate stabilization, and immense economic benefits.
There are two forest bioclimatic zones in Canada - boreal and temperate. Each zone possesses a unique geography, vegetation, climate, soil, and wildlife. Canada has approximately 24 and 15% of the world's boreal and temperate forests,3-5 and 9% of the world's total forest cover.4 The boreal forest stretches across eight ecozones+ (see map). It is the largest contiguous forest ecosystem on Earth, and Canada's largest biome, covering 25% of its total land area and 72% of its total forest area.1
Spruce forests dominate all boreal forest ecozones+.5 Black spruce forests are of particular ecological significance because of their nearly continuous ground cover of lichens, feather mosses, and sphagnum mosses. Lichens are critical forage for wintering migratory caribou herds and mosses provide habitat for a number of species. In northern Quebec, 9% of the dense black spruce forest has shifted to lichen-woodland systems over the past 50 years.6 The proportion of the boreal forest that is dominated by spruce has decreased in the managed forest portion of Ontario's Boreal Shield,7 and in the southern part of Manitoba's Boreal Shield.8 Spruce is also declining outside the boreal forest.9,10
The temperate forest stretches across six ecozones+ and tree species are more variable. Dominant species include spruce and maple in the Atlantic Maritime, deciduous species in the Carolinian forest of the Mixedwood Plains, spruce and pine in the Montane Cordillera, and hemlock in the Pacific Maritime.5
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