Spruce beetle activity continues to decline on the Rio Grande National Forest according to 2017 aerial survey data. The tiny bark beetles spread into 7,000 acres of uninfested forest last year, as compared to infesting 22,000 acres in 2016. They were still active on 47,000 acres, down from 93,000 acres the previous year. A total of 617,000 acres of high and mid-elevation forests have been infested by spruce beetles since 2002.
Spruce beetles mostly infest Engelmann spruce in Colorado, but will also attack some blue spruce. The beetles are native to North America and have been killing most of the Engelmann spruce trees in infested areas that are larger than five inches in diameter.
“There aren’t many more areas for the beetles to spread into,” said Rio Grande National Forest Vegetation Program Manger Kirby Self. “While there was nothing we could do to stop this epidemic, we have been able to increase the amount of dead trees salvaged from the Forest while the timber still has commercial value.”
The amount of timber harvested per year from the Rio Grande National Forest has tripled since 2002. Twenty-four of the 25 timber sales currently under contract are salvaging beetle-killed trees. All of the timber sales are located in areas that allow for commercial timber harvest in the 1996 forest plan. “Only about nine percent of the beetle-killed spruce on the Forest is accessible to salvage,” continued Self. “We primarily use existing roads with some construction of temporary roads that are closed and rehabilitated following harvest.”
Beetle-killed spruce trees generally lose their value for use as sawtimber after about 10 years due to rot or deep cracks that form in the trunk as they dry out. Those trees that don’t rot can still be used for house logs, firewood and biomass. Using trees for biomass generally involves turning the dead wood into pellets to produce heat in pellet stoves or shredding it for use in landscaping or livestock bedding.
From Alamosa News: https://alamosanews.com/article/rg-national-forest-puts-dead-trees-to-use