A SPECIAL REPORT: Last of three parts Forests encounter new pest problems in the age of global warming
By MITCH LIES East Oregonian Publishing Group
For 75 years, the mountain pine beetle has been a pest of concern for the Canadian Forest Service because of its ability to decimate lodgepole pine. Nothing, however, could have prepared Forest Service officials for what they now see.
As part of a steady migration east, the pine beetle last year infested 8.7 million hectares of British Columbia forests, or about 20 million acres. Scientists believe global warming, caused by increased greenhouse gas emissions, is the major cause of the increase in beetle numbers.
"The winters are so mild anymore, they have not killed the adult beetle," said Oregon State University plant pathologist Stella Coakley.
Added to Canadian Forest Service concerns in recent years is a needle blight also harming lodgepole pines at an unprecedented rate. Dothistroma needle blight, long considered a major pest of pine plantations in the Southern Hemisphere, was until recently a minor pest of the pine in Northwest British Columbia, where the lodgepole pine flourishes. Increases in summer rains, however - considered an occurrence in the first stages of global warming - have triggered more blight, and the disease today is defoliating pine at an alarming rate.
The devastation of the lodgepole pine, scientists believe, is a prime example of what can happen - and will happen to international forests - if global warming goes unchecked.
Canadian Forest Service officials this year have adopted a new approach to stopping the beetle. They hope that by taking out infested trees before adult beetles fly east, they can slow its spread - a spread that threatens millions of acres of forests in Alberta, and a spread U.S. Forest Service officials fear eventually could inch down the Eastern Seaboard into U.S. forests.
British Columbia and Alberta forests and range ministries spent $17 million on this tactic this year, taking out 45,000 infested trees this winter.
But scientists question the benefits of efforts to control the beetle's range in absence of efforts to stem global warming.
Ron Neilson, a U.S. Forest Service bioclimatologist, said the beetle is indicative of a shift in pest pressure now being seen throughout the world. Essentially, Neilson said, some pests - pests that easily adapt to new environments and pests that disperse rapidly - are surviving better than others in a world where the average temperature is rising and habitat is changing.
An example Neilson brings up is the barred owl, which has moved west from its natural habitat and is now displacing the Northern spotted owl in Northwest forests. The barred owl, he said, is highly adaptive to different regions, while the spotted owl, a classic example of an endangered species, is not. As the climate warms, the same type of scenario will play out again and again in the animal and plant world, Neilson said.
Other examples of pests new to regions in recent years include the mountain bark beetle, which is causing massive damage to trees in Idaho's Salmon River Valley forests; and the southern pine beetle, which is causing extensive damage to spruce and fir trees in the Southern Appalachians.
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