Pines, Beetles and Bears

White bark pine forests are in trouble all across Wyoming, Idaho and Montana. Great swaths of trees are dead or dying after being attacked by the mountain pine beetle and a disease called white pine blister rust. The forests used to be protected by harsh winters and cool summers. But warmer winters and summers have allowed the beetle to breed more quickly and to move to the higher elevations favored by white bark pines.

Last summer, pilots working with the United States Forest Service and the Natural Resources Defense Council made low-level flights over 25 million acres of forest, trying to gauge how much damage has been done. The results, released this month, are devastating. Just over half the white bark pine forests are dead; one-fourth have medium to high mortality; few forests have escaped some damage.

The wider ecological effects could be serious. These forests slow the rate of spring snowmelt; without them, the spring runoff will happen faster and streams and rivers will see reduced flow and higher temperatures later in the season. The loss of the pines also threatens the symbiotic relation between the Clark’s nutcracker and the pines, which depend on the bird for reseeding, as well as red squirrels, which gather pine nuts.