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San Juan National Forest plans response to spruce beetle activity

Pine trees in the White River National Forest near Frisco glow rusty red after being killed by the mountain pine beetle.

The San Juan National Forest announced Tuesday that it is working on several proposals this year in its battle with the spruce beetle, including public involvement and environmental analyses.

According to an annual aerial survey conducted by the U.S. Forest Service and the Colorado State Forest Service, the devastation caused by spruce beetles across Colorado forests accelerated for a fourth consecutive year. The once widespread infestation of pine beetles has largely subsided, according to the survey.

The spruce beetles were found to have newly infected 182,000 acres of previously unaffected forests, bringing the number of acres currently impacted to 409,000 across the state.

The bug has caused varying degrees of tree mortality to nearly 1.6 million acres across the state since 1996, though still far less than the mountain pine beetle.

Two other defoliators of conifers — the western spruce budworm and the Douglas-fir tussock moth — also expanded their reach last year, touching nearly 340,000 acres of forests.

San Juan National Forest officials said in a news release that it plans a small salvage sale this year for about 100 acres of dead spruce in the Pagosa Ranger District near Wolf Creek Pass. The district also said it is considering salvaging dead spruce near Wolf Creek and Falls Creek roads.

“Both proposals focus on the harvest of dead merchantable trees, retention of live green trees, and using receipts from the sale of timber to promote reforestation in areas of heavy mortality,: the San Juan district news release said. “Dead spruce trees can remain standing for several decades and retain value as commercial timber for up a decade or more.”

The Dolores Ranger District is reportedly considering a timber sale for 900 acres of mixed spruce and aspen in the Taylor and Stoner Mesas. The purpose of that sale, the district said, is to strengthen spruce forests that haven’t been hurt by beetles, but has been affected by spruce budworms. Mitigation such as thinning green stands can improve forests by encouraging natural regeneration, but can’t stop the spread of insects.

The Columbine Ranger District is considering salvage sale in an area north of U.S. Highway 160 between the Piedra River and Vallecito, as well as mitigation in live spruce and aspen forests, fuels reduction and prescribed burning.

The mountain pine beetle, which has ravaged more than 3.3 million acres of Colorado forests since 1996, has dwindled to about 5,000 new impacted acres, and the epidemic has ended in some areas as mature pine trees have been depleted, the survey notes.

The pine beetle infestation that ran across Colorado, Wyoming and South Dakota has affected an area roughly the size of Massachusetts.

“The lesson we can take away from the extensive insect and disease damage we’ve seen in Colorado over the past two decades is the need for proactively taking care of our forests,” State Forester Mike Lester, who is also director of the Colorado State Forest Service, said in a press release. “The best time to take actions to address long-term forest health is before a major outbreak starts, and not after.”

Much of the reason for the spruce beetle problem continues to be blown-down trees, drought stress, warmer temperatures, an extensive number of older trees and a high density level, the Forest Service said.

The Denver Popst contributed to this article.

May 30, 2017
Spruce, fir sale designed to combat budworm infestation