Forests

Photo: Gros Morne National Park, Newfoundland and Labrador © iStock.com/Mmac72
Gros Morne National Park, Newfoundland and Labrador

Intactness of Canada's landscapes

Canada is one of the few countries that still have large tracts of forests, relatively undisturbed by human activity, that are believed to contain most of their native biodiversity. Just how intact Canada's forests are depends on how they are measured and, as Long et al.26 point out, measuring intactness, or its corollary, fragmentation, can be complex. Global Forest Watch measured intact landscapes as undisturbed areas, free from human impact, and at least 50 km2 in size for the boreal and taiga forest ecozones, and 10 km2 for temperate forest ecozones.27 B.C. defined intact coastal rainforests as undisturbed landscapes greater than 500 km2.17 The Alberta Biodiversity Monitoring Institute has taken a different approach, measuring intactness as a percentage of what would be expected in a pristine habitat.28

Global Forest Watch has published the only national perspective on intactness (see map) concluding that almost 50% of Canada's total land area, and more than 50% of the area of Canada's forested ecozones, consist of intact forest landscapes. This includes 94% of the northern boreal ecozones (using the Terrestrial Ecozones of Canada classification system29) – Taiga Cordillera, Boreal Cordillera, Hudson Plains, and Taiga Shield – and 73% of the Taiga Plains. The southern boreal regions are more impacted by human activities. Thirty-seven percent of the Boreal Plains remains as intact forest landscapes. About 42% of the temperate forest ecozones remains as intact forest landscapes. Ninety percent of this area is in B.C., the remainder is in Alberta.27 In North America, the only remaining intact coastal temperate rainforest is in B.C. and Alaska. Approximately one-third of B.C.'s remaining coastal temperate rainforest is intact, in patches greater than 500 km2.17

Map: Intactness of Canada's landscapes. Click for graphic description (new window).
Note: Intact landscapes are defined as >50 km2, for the boreal forest,and >10 km2 for the temperate forest.
Sources: adapted from Lee et al., 201027

Forest fragmentation occurs when large, continuous forests are broken up into smaller patches. It can result from human activities such as clearing for agriculture, urbanization, oil and gas exploration, and roads,30 as well as from natural processes such as fire and insect infestations.31, 32 Natural disturbance is discussed elsewhere in this report; the discussion here focuses only on fragmentation from human activities. The impact of forest fragmentation by human activities is dependant on the species and the spatial scale. Impacts can include: declines in neotropical migrant and resident birds requiring interior forest habitat;33 declines in species with large area requirements, such as grizzly bear and caribou; increases in species that prefer to browse along forest edges, such as moose; increased exposure of interior forest species to predators and parasites; disruption of social structure of some species34 and barriers to dispersal.30 Sustainable forest practices can be designed to mitigate the effects of fragmentation.

Intactness of old forest habitat in Alberta-Pacific Forest Management Area

Percent intact
Graph: intactness of old forest habitat in Alberta-Pacific Forest Management Area. Click for graphic description (new window).
 
Source: adapted from Alberta Biodiversity Monitoring Institute, 200928
 

The Alberta Biodiversity Monitoring Institute measured habitat intactness and the human footprint of the Alberta-Pacific Forest Management Area (Al-Pac FMA). This area encompasses 57,331 km2,28 and makes up 9.5% of the Boreal Plains ecozone+.5 Old-forest habitat in the Al-Pac FMA is 92% intact. That is, it occupies 92% of the area that it would be expected to occupy if there were no human impacts. The human footprint index shows that human influence is evident in 7% of the Al-Pac FMA. Most of the human footprint is due to forestry, energy and transportation infrastructure. Half of the forestry footprint was created in the last 10 years.28