A changing climate will affect Canada’s forests in a range of complex ways. Some effects will be sudden and dramatic and others will be gradual and subtle.
Rapid climate change will affect tree growth rates, mortality rates, disturbance patterns and the distribution of tree species after disturbances. Impacts will be cumulative and interconnected. For example, insect damage can increase the risk of wildland fires occurring; and drought can stress trees, making them more susceptible to attack by insects and disease.
One thing is clear: the future will not be like the past.
Change is underway
Scientists have already documented changes in our forests linked to recent climate changes. Recent examples include:
- the major infestation by mountain pine beetle in British Columbia
- increased fire activity in the western boreal forest
- increased aspen dieback in the Prairies
Even tree phenology in Canada’s forests appears to be changing, with earlier arrival of spring weather and longer summers affecting the timing of dormancy, leafing out, flowering and seeding.
More disruption to come
What could happen if the pace of climate change accelerated or even continued as it is today? Some of the outcomes scientists have suggested:
- Forest composition may change, favouring those populations of tree species best able to adapt to new climate conditions and altered disturbance regimes. In some cases forests can be converted to grasslands.
- Forest productivity may increase in some regions and decrease in others as rates of tree growth and tree mortality fluctuate.
- Some habitats may disappear and some may shift northwards or to higher elevations.
- Most areas may experience novel climate. This means that tree species may be increasingly maladapted to new climate regimes and will therefore undergo stress.
- Fire activity may increase, with the area burned each year potentially doubling by the end of this century.
Changes in the forest mean changes for society
Forestry-dependent communities and Aboriginal communities will be the first to feel the impacts of any timber supply disruptions or losses of other forest values as a result of changing climate conditions.
Catastrophic wildland fires are of particular concern because they pose direct threats to communities and human well-being. Aside from the smoke pollution and property damage they cause, some fires may even result in loss of human life and many homes.
Changes in tree growth and in patterns of disturbance would also affect both the amount and quality of wood coming from the forest. Such swings have major implications for forestry-reliant rural economies. Some of the changes in forest sector activity could be gradual; others could be sudden and dramatic—as the mountain pine beetle outbreak has shown. The extensive and relatively fast mortality caused by the beetle infestation has led to short-term increases in timber supply while the beetle-killed wood is salvaged. However, once that wood runs out, the annual harvest is expected to decline significantly.
Another concern is that a warming trend could reduce the season and limit the use of winter roads in regions where winter forestry operations are the norm in Canada.
An essential role for science
CFS scientists are studying many aspects of the impacts of climate change on Canada’s forests to provide a basis for future forest policy and management. For example:
- Researchers have used climate change scenarios of the Intergovernmental Panel on Climate Change to develop an online tool that maps how the climatic ranges of more than 3000 species may respond to climate change.
- Some studies are addressing forests’ sensitivity to climate change, analyzing the role of Canada’s managed forests in the carbon cycle, and assessing changes in ecosystem composition and processes and in disturbance regimes.
- Researchers are looking at the forest sector’s capacity to adapt to climate change.
- Efforts are underway to improve forest monitoring, using remote sensing from aircraft and satellites, and to understand the responses of forests to variations in climate.
Managing our forests in a changing climate
A changing climate will certainly have wide-ranging effects on Canada’s forests and forest sector—some beneficial and some costly. The decision-making context for forest management will be increasingly complex and uncertain.
Does forest management play a role in the forest carbon balance?
Yes, forest management activities such as harvesting, tree planting, and efforts to fight forest fires and insects have an impact on the forest carbon balance. In some cases, suppression of fires and protection against insects can lead to a reduction in the area affected and help maintain the carbon stored; however, our ability to reduce fire and insect impacts on carbon in the long term or over large landscapes is uncertain. Harvesting results in large losses of carbon from the forest in the short term, but the regeneration of the trees then takes up large amounts of carbon. As well, much of the harvested carbon is stored for a long time in forest products that society needs.
Addressing the challenges brought on by climate change will require forest managers to be more flexible, more forward looking and more adaptable than ever before. And, if they are to meet these responsibilities effectively, forest managers will also be relying more than ever on better monitoring and decision support. It is these capabilities that will equip managers and other forest decision-makers with critical information about where and how rapidly changes are occurring.
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