Climate Change: How it Will Affect Our Forests
S&W Report Summer / Fall 1998 Volume 12
Climate change is not a new concept; the weather is synonymous with change. What is new (at least in this century) is the rate at which climate is changing and the effect rapid change till have on our environment. The Canadian Forest Service Climate Change Networking is studying climate change and its influence on the forest.

"Pollen core analysis has determined that during the last ice age there were vary rapid changes in climate over 50 - 60 year period, so it is not improbable that this is happening again," says Ross Benton; forest climatologist working at the Pacific Forestry Centre. "Impacts of climate change on Canada's forests may include changes in growth and ranges of existing tree species, changes in ecosystem functioning, and changes in disturbance regimes related to fire, insects, and disease."

One of the areas that has experienced considerable climate change is the Canadian North, where EI Nino has created a 10 degree increase in temperature (in the Yukon). Using forest-modeling dynamics, the Climate Change Network has been part of an interagency, multisector Mackenzie Basin Impact Study looking at the potential impacts of global warming on Canada's northern forests.

"We are studying the potential changes to the forest from now until 2050; how climate changes will affect the biology of the vegetation, which will undoubtedly change," says Benton. "One important discovery is that there may not be so much a shift in the species itself but in the composition of species existing in the north. There may be more coniferous species, which would be good for economic reasons, but a longer fire season could develop in the territories, which is a major form of change of vegetation. As well, increased temperatures will provide sufficient growing season heat to allow the spruce weevil to expand its range northward in latitude and upward in elevation to occupy the white spruce in the Mackenzie Basin. That could have a huge impact on the area."

Besides the devastating effects climate change could have on the North, increasing temperature could mean an increase in vegetation. However, as Benton explains, the weather may be warmer but the growing season is still limited by the rotation of the earth; the length of daylight hours affects vegetation. "There is also a lack of soil development on the Canadian Shield which will restrict vegetation growth. How ill accelerated rates of permafrost thawing influence vegetation?"

As in many complex ecosystems, no change occurs in one area without creating changes in other parts of the forest. Understanding, predicting and assessing these changes is critical to the sustainable management of our forests.

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