More Pine Forests Succumbing to Mountain Pine Beetle Infestation

The bark beetle problem extending from New Mexico to British Columbia is getting worse, turning the region’s signature pine forests from green to rust red. Montana has already lost a million acres, and the news in Colorado and southern Wyoming is even worse. In Montana’s capital city, Helena, loggers are racing to cut down infected trees to stop the beetles from spreading.

From The New York Times:

In Wyoming and Colorado in 2006 there were a million acres of dead trees. Last year it was 1.5 million. This year it is expected to total over two million. In the Canadian provinces of British Columbia and Alberta, the problem is most severe. It is the largest known insect infestation in the history of North America, officials said. British Columbia has lost 33 million acres of lodgepole pine forest, and a freak wind event in 2006 blew mountain pine beetles, a species of bark beetle, over the Continental Divide to northern Alberta. Experts fear that the beetles could travel all the way to the Great Lakes.

In the next three to five years, Mr. Kyhl said, virtually all of Colorado’s lodgepole pine trees over five inches in diameter will be lost, about five million acres. “Already in many places, every lodgepole over five inches is dead as far as the eye can see,” he said.

Foresters say the historic outbreak has several causes. Because fires have been suppressed for so long, all forests are roughly the same age, and the trees are big enough to be susceptible to beetles. A decade of drought has weakened the trees. And hard winters have softened, which allows the beetles to flourish and expand their range.

The beetle drills through the pine bark and digs a hole in the wood where it lays its eggs. The larvae inject a fungus to stop the tree from moving sap, which could drown them, and that fungus stains the wood blue. The trees emit a white, candle wax-like resin into the beetle’s drill hole in an attempt to fight them off, which sometimes works – but in some cases, the beetle emits a pheromone call for reinforcements, causing a swarm that kills the tree.

The reason for all of this? Warming temperatures. Decades ago, temperatures dropped to 30 or 40 degrees below zero in the Rockies, which kept infestations like this at bay. Now, the beetles have free reign. And, the death of all these trees is of course having a major effect on the forest ecosystem. In Yellowstone, for example, the white pine trees falling prey to the beetles grow nuts rich in fat, which grizzly bears depend upon for survival. Flash floods could also be a problem, and all of these dry forests are at major risk of fast-spreading fire.

This is one of the most obvious ways in which we’re already experiencing the effects of global warming here in North America. If this isn’t a blaring siren of warning, I don’t know what is.

Link [The New York Times]
Photo credit: Dion Manastyrski, B.C Ministry of Forests and Range

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