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Cumulative Impacts That Threaten Sustainable Use

Human activities place increasing pressures on the boreal forest ecosystem. Stresses are greater in some regions than in others. It is the intensity and combination of these stresses that, over time, may ultimately test the resilience of the ecosystem.

Forest management practices such as fire suppression, insect control, clearcutting, and tree planting occur in commercially available forests. There is increasing concern that these practices may, over the long term, shift species composition, reduce species and genetic diversity, and increase the forest's vulnerability to other disturbances.

Forest land may be removed permanently for alternative uses such as roads, power and pipeline corridors, hydroelectric development, mining, urban development, and recreational use. Large-scale land use changes such as major hydroelectric project can alter ecosystem function, eliminate wildlife habitat, and otherwise profoundly affect wild species and their populations. The life styles of the Aboriginal inhabitants of an area may be affected as well. The additive effects of even small-scale land use changes can result in substantial losses and disruptions over time.

Herbicides, pesticides, and contaminants in emissions from industrial processing also affect the ecosystem. Acidic deposits from the long range transport of airborne pollutants have affected aquatic life in many lakes in Ontario and Quebec. These pollutants may also weaken the vigour and growth of trees in sensitive areas of the boreal forest. Many of these airborne contaminants come from sources outside the boreal forest.