America's Disappearing Forests

The tiny mountain pine beetle is destroying millions of acres of forests. It's the largest insect infestation in the history of North America.

Barely the size of a grain of rice, mountain pine beetles are devasting forests ranging from Mexico through the Western U.S. into Canada. This thorough New York Times video investigates what some are calling “the worst crisis to hit American forests.” Aided by mild winters and declining rainfall, the minuscule marauder is shaping up to redesign parts of the North American landscape and aid the ever-increasing effects of global warming as it kills off thousands of trees per year in the U.S. with little end in sight.

Montana has lost a million acres of trees to the beetles. 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. 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.

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 softer winters have allowed the beetles to flourish and expand their range. Hoping to keep their forests from completely dying, to earn money by selling dead and infected trees, and to mitigate fire risks, landowners are scrambling to cut the pines. If enough are cut — up to 75 percent — it might leave some behind that, with less competition for water, can survive.

As scientists and park authority struggle to reach a consensus on how to overcome this insect epidemic, the story is likely to grow even as our forests shrink.

Length: 6:39

Video: Erik Olsen
Photography: Ray Blanchard

VIEW: http://video.nytimes.com/video/2008/11/17/science/1194833211431/americas-disappearing-forests.html

SEE ALSO:

Bark Beetles Kill Millions of Acres of Trees in West:
http://www.nytimes.com/2008/11/18/science/18trees.html

In the West, Beetles Become Business Opportunities:
http://greeninc.blogs.nytimes.com/2008/11/19/beetles