TREE KILLER: The mountain pine beetle has devastated so many pines in the western U.S. that its numbers have begun to decline.
Image: flickr/vsmoothe
The mountain pine beetle infestation that has ravaged swaths of Western forests is slowing down for the second year in a row, the Forest Service said yesterday.
The massive area of public forestland -- about 750 million acres -- with trees killed by the mountain pine beetle decreased by 3 million acres between 2010 and 2011, according to a report from the Forest Service. Northern Idaho saw a decrease of nearly 80 percent in beetle-damaged lands from last year.
Dwindling reserves of the beetle's choice food, the lodgepole pine, have limited its ability to proliferate, said Robert Mangold, associate deputy chief for research and development for the Forest Service.
"They are running out of susceptible hosts," Mangold said. "We expect the beetle population numbers to drop dramatically over time."
In 2009, acres destroyed by the mountain pine beetle -- mostly in the forests of Wyoming, Montana, Colorado and Idaho -- reached a historic peak of 9 million acres. Since, the numbers have been tumbling. About 6.8 million acres of forests showed pine beetle damage in 2010, and 3.8 million acres was affected in 2011.
A series of interacting factors that include drought, wildfires and tree health play into the cycle of pests in forests, but the interactions can be elusive, Mangold said. Drought can make trees weaker and more susceptible to insect attacks. In turn, trees killed by pests can provide fuel to wildfires, aiding the spread of flames.
Not out of the (fire-prone) woods, yet
Warmer winters encouraged beetle populations in the years before the 2009 peak, said Mangold, who sees the decline as part of a cyclical pattern in forest ecology.
The downward trend in pine beetle infestations is a positive one, said William Anderegg, a researcher at the Carnegie Institution for Science in Stanford, Calif., who studies how and why forests die. However, to assess the effect of climate change, observations must be made over decades, not years.
"Year-to-year variation is often the noise, but it's the long-term trend (which has been increasing substantially in the bark beetle case) that is a sign of climate change," he wrote in an email.
More research has been conducted on lodgepole pine and mountain pine beetles than any scientific investigations on forest die-off, said Anderegg, who recently co-wrote a paper documenting the patterns of dying forests around the world for Nature Climate Change.
Nevertheless, research into the roots of forest mortality has been minimal to date, he said. Anderegg's recent paper called for a coordinated international effort to better understand the interactions that drive dying forests.
"Sadly, our monitoring efforts are so incomplete that it's tough to make these cross-nation and cross-continent comparisons," he said.
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500
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4 Comments
Add CommentThe pine beetle is now in the South East part of the US & its just been in the last few years that its become a real problem & seems to be accelerating.
Reply | Report Abuse | Link to thisI'm in Mississippi.
The Southern Pine Bark Beetle should really be named The Southern Loblolly Pine Bark Beetle. The coming of The Pine Bark Beetle is the same as The Second Coming of the Bowl Weevil. In the South many acres of trees will soon be worthless. If anyone knows whatever made the commissars in the United States Department of Agriculture decree that Southern forests should use loblolly pine monoculture, please let me know. What did they have against the comrades working southern farms? Their program successfully collectivized the small farm holdings.
Reply | Report Abuse | Link to thisI know of the "Bol Weevil" but is this "Bowl Weevil" a new pest that the civilisesd world is woefully ignorant ??
Reply | Report Abuse | Link to thisIn the United States many southern farms have been removed from cultivation of annual crops and planted in loblolly pines. Also in Florida, many acres that were planted in oranges froze. They were replanted in loblolly pines. Where mixed forest existed before white man came, monoculture forest now exists. When there is an El Nino, the South Eastern part of the United States has a monsoon and the forest grows fast, meanwhile things are dry in India. When there is a La Nina, the South Eastern part is dry and the trees are stressed. (India has its monsoon.) When the trees are stressed, the pine bark beetles multiply. They strive in the stressed trees.
Reply | Report Abuse | Link to thisCotton was a monoculture crop in the Southern United States. The bowl weevil did so much damage because it could simply spread from field to field. No natural barrier existed. It did not need to search for the next cotton field.
Comparing the destruction of a monoculture crop by a single pest to the destruction of another monoculture crop by a single pest uses a metaphor.
I could have simply said, "A great loblolly pine forest exist in the Southern United States. Due to stress on those trees that forest has become infected with pine bark beetles infecting mainly loblolly pines. Those beetles could have the same effect as the bowl weevil did in an earlier era."
I hope the simile explains my metaphor.