Emblem of the West Is Dying, and No One Can Figure Out Why

The aspen, an emblematic tree of the West and the most widely distributed tree in North America, is rapidly and mysteriously dying.

Its rapid decline is bewildering scientists and forest ecologists, who say they cannot pinpoint a cause.

“What’s causing the aspen to die?” asked Wayne Shepperd, a veteran researcher at the Rocky Mountain Research Center of the United States Forest Service. “We don’t know. Maybe this has been there all along, and we haven’t noticed it before, or maybe it’s something new.”

There is no shortage of suspects. Forest experts, who met this month at a conference in Utah to discuss the problem and look for solutions, say it may be insects, drought or climatic stress in general or overgrazing by animals like elk and cattle. Or it may be none or all of the above.

from the NY Times