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University of Montana study predicts major changes in Montana's forests
November 11, 2011
Editor@montanaliving.com
A new study co-written by University of Montana Regents Professor Steve Running suggests that climate change, insect attacks, diseases and fire will cause many tree species across the Northwest to migrate, decline or even die out over the next few centuries.
The study, published in the journal Remote Sensing and the Environment, outlines the impact that a changing climate will have on which tree species can survive, and where. The study suggests many species that were once able to survive and thrive are losing their competitive footholds, and opportunistic newcomers will eventually push them out.
In some cases, once-common species such as lodgepole pine will be replaced by other trees, perhaps a range expansion of ponderosa pine or Douglas fir. Other areas may shift completely out of forest into grass savannah or sagebrush desert.
“In Montana, our forests overall have been expanding over the past century, mostly as a result of wildfire suppression and grazing controls,” said Running, an ecology professor in UM’s College of Forestry and Conservation. “Some of the recent large beetle-kill forests may now come back in today’s warmer climate as savannah grasslands or shrub lands.”
Running collaborated with Oregon State University’s Richard Waring and the University of British Columbia’s Nicholas Coop on the study, which used remote sensing to survey large areas over a four-year period. It compared 15 coniferous tree species found widely across much of the West and explored impacts on 34 different “eco-regions” as far north as the Yukon highlands in Canada and as far south as the Sierra Nevada in California.
It projected which tree species would be at the highest risk of disturbance in a future that’s generally expected to be 5 to 9 degrees Fahrenheit warmer by 2080, with perhaps somewhat more precipitation in the winter and spring, and less during the summer.
“Ecosystems are always changing at the landscape level, but normally the rate of change is too slow for humans to notice,” Running said. “Now the rate of change is fast enough we can see it.”
“Some of these changes are already happening, pretty fast and in some huge areas,” Waring said. “In some cases the mechanism of change is fire or insect attack; in others it’s simply drought.”
According to Waring, tree species that are native to a region are there because they can most effectively compete with other species given the specific conditions of temperature, precipitation, drought, cold tolerance and other factors that favor one species over another in that location.
As those climatic conditions change, species that have been established for centuries or millennia will lose their competitive edge and slowly decline or disappear.
“We can’t predict exactly which tree will die or which one will take its place, but we can see the long-term trends and probabilities,” Waring said. “The forests of our future are going to look quite different.”
Though the rate of change has increased, these processes will take time, the scientists said. A greater stability of forest composition probably will not be attained for centuries.
“There’s not a lot we can do to really control these changes,” Waring said. “For instance, to keep old trees alive during drought or insect attacks that they are no longer able to deal with, you might have to thin the forest and remove up to half the trees. These are very powerful forces at work.”
One of the best approaches to plan for an uncertain future, the researchers said, is to maintain “connective corridors” as much as possible so that trees can naturally migrate to new areas in a changing future and not be stopped by artificial boundaries. |
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