Friday, June 15, 2012

The West's trees being decimated by pine beetle fungus; some say they're telling us something

North America is witnessing the largest pine-beetle epidemic in recorded history, reports Sophie Quinton of the National Journal. From Canada’s Yukon Territory to New Mexico, pine trees by the hundreds of millions are succumbing to a fungus that the beetles carry. Jeff Mitton, an evolutionary biologist at the University of Colorado (Boulder), has been studying the mountain pine beetle for more than 30 years. “The question is, why has this gotten so much worse?” Mitton said. Among the scientific community, a consensus is growing that changes in climate have propelled the outbreak. (AP photo of Colorado state park)

It's natural that beetles kill, die off, and regenerate, but human activity has helped to set the stage for the current epidemic. Writes Quinton: "Decades of fire suppression have left the West with dense stands of vulnerable, elderly trees. Frigid winters that usually kill the beetles have become, over the past 20 years, the exception rather than the rule. Earlier snow-melt and longer summers have altered the beetles’ range and life cycle; they now attack pines at higher altitudes and latitudes, and they reproduce twice a year instead of once. Earlier springs and a series of dry years have also weakened trees, turning them into ideal beetle food."
The devastation of the forest has been vast. The infected trees first turn a violent red, then they fall, and, finally, the tree falls. "Year by year, communities have watched a scourge advance across mountainsides and through neighborhoods, trees turning from green to red to gray. The beetles now attack 12 pine species, from the high-elevation whitebark pine to the lower-elevation ponderosa and piƱon." The blight has overtaken 3.3 million acres in Colorado alone since the 1990s. “To a large degree, our nation’s parks are the canary in the coal mine when it comes to on-the-ground effects of a warming climate,” U.S. Sen. Mark Udall (D-Colo.) said at a 2009 hearing on climate change at held at Rocky Mountain National Park with Sen. John McCain, R-Ariz. At the same park, John Mack, the chief of resource stewardship told Quinton: “These trees are dead; they just don’t know it.”

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