Grim outlook for US forests because of bugs, disease

Scott Condon in the Post Independent (Glenwood Springs, Colorado): The outlook for forests in western North America is grim: White pines in majestic Yellowstone National Park face obliteration; two-thirds of aspen forests, including many in the Roaring Fork Valley, are likely doomed; and bark beetle infestations will intensify with climate change.

The grim outlook was delivered Friday by scientists at the “Forests at Risk” conference in Aspen. More than 400 conservationists, U.S. Forest Service workers and curious folks attended the conference presented by For the Forests, an Aspen nonprofit. “There wasn't much good news in anything any of you had to say,” moderator Renee Montagne of National Public Radio told a panel featuring the first four presenters at the conference.

Tom Swetnam, professor and director of the laboratory of tree-ring research at the University of Arizona, said climate change will exacerbate the drought cycles that the study of tree rings show have regularly occurred in North America. There might be more rainfall as a result of climate change, he said, but it will be more than offset by higher temperatures.

That will create problems for virtually all species of trees in western forests. Jim Worrall, a plant pathologist with the U.S. Forest Service and a top expert on Sudden Aspen Decline (SAD), said there is “overwhelming circumstantial evidence” that the problem is tied to climate change. The drought that peaked in Colorado and much of the West in 2002 stressed trees and made them more susceptible to bugs and diseases. SAD mortality in aspen trees peaked in 2008 when 542,000 acres of the iconic tree died off.

…Swetnam said public land managers can't concentrate on restoring forests to a past condition. The changes have been too drastic. The focus should be getting forests into conditions where they can be resilient over time. That will require use of prescribed fire. Fire fighting has been eliminated as part of “the Smokey Bear effect,” he said, referring to the Forest Service firefighting. “We need to reintroduce fire,” Swetnam said, stressing that “we can't just rely on chainsaws.”…

Aspen trees in fall color on the North Kaibab Ranger District in Arizona. From U.S. Forest Service, Southwestern Region, Kaibab National Forest. Posted to Wikimedia Commons via Flickr, under the Creative Commons Attribution-Share Alike 2.0 Generic license