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Colorado State Forest Service News

Forestry Agencies Release 2015 Aerial Survey Results for Colorado

A larva feeding on foliage showing the four cream-colored tufts with the orange-red-colored tops. Photo: Dan West
A Douglas-fir tussock moth larva feeding on foliage showing the four cream-colored tufts with the orange-red-colored tops. Photo: Dan West

GOLDEN, Colo. – Today, the Colorado State Forest Service (CSFS) and U.S. Forest Service (USFS), Rocky Mountain Region, released the 2015 forest health aerial survey results for Colorado.

Every year the USFS and CSFS work together to aerially monitor forest health conditions on millions of forested acres across the state. Aerial survey observations of tree-damaging insects and diseases native to Colorado’s forests are highlighted below.

2015 Aerial Survey Highlights

Spruce beetle outbreaks caused widespread tree mortality for the fourth consecutive year

  • Spruce beetle populations have expanded, impacting higher-elevation stands of Engelmann spruce.
  • In 2015, spruce beetle infestations were detected on 409,000 acres across the state, expanding onto 182,000 acres of previously unaffected forests.
  • Since 1996, spruce beetle outbreaks have caused varying degrees of tree mortality on more than 1.5 million acres in Colorado.
  • Blowdown events, combined with long-term drought stress, warmer temperatures and extensive amounts of older, dense spruce, have contributed to this ongoing epidemic.

Outbreaks of two defoliators of conifer trees – western spruce budworm and Douglas-fir tussock moth – also expanded in 2015

  • The area impacted by western spruce budworm, Colorado’s most widespread forest defoliator, increased from 178,000 acres in 2014 to approximately 312,000 acres in 2015. This insect typically feeds on developing buds and new needles of fir, Douglas-fir and spruce in southern Colorado.
  • Douglas-fir tussock moth caterpillars consumed needles on Douglas-fir, white fir and spruce on approximately 26,000 acres along Colorado’s Front Range. Impacts were observed primarily in the South Platte River Basin and areas just west of Colorado Springs. Ground surveys have documented the presence of a naturally occurring virus among Douglas-fir tussock moth caterpillars, which has historically been a key indicator of imminent population collapse.
  • Trees weakened by these defoliators may become susceptible to Douglas-fir beetle, which can kill impacted trees.

Mountain pine beetle activity has subsided and remains low, with 5,000 acres affected statewide. The epidemic has ended in many areas of Colorado as mature pine trees have been depleted in the core outbreak areas.

“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,” said Mike Lester, State Forester and Director of the Colorado State Forest Service.

“The best time to take actions to address long-term forest health is before a major outbreak starts, and not after.”

Agency Highlights

In 2015, the CSFS treated more than 17,000 acres in Colorado, predominantly on private and state lands, as part of forest management and wildfire mitigation efforts.

The CSFS is committed to providing timely, relevant forestry information and education to the citizens of Colorado to achieve resilient forests and communities. CSFS Quick Guides on spruce beetle and Douglas-fir tussock moth are available free on the CSFS Publications web page. Another guide on Douglas-fir beetle will be available the first week of February.

The USFS is committed to ecological restoration, which includes maintaining and restoring healthy and diverse landscapes, promoting resilience in the face of climate change and other stressors, reducing the risk to communities and natural resources from wildfire, and sustaining diverse wildlife habitat. Along with partners, the USFS is investing in several projects to improve forest health.

“Although forests in Colorado have experienced a series of insect infestations, we continue to invest in projects with local and industry partners, ahead of and behind the infestations, to improve forest health,” said Dan Jirón, Regional Forester for the Rocky Mountain Region of the U.S. Forest Service.

Last year in Colorado the USFS treated approximately 51,020 acres through timber sales, thinning and prescribed fire. A total of 268,000 CCF (hundred cubic feet) of timber was sold, which equates to the framing lumber and other wood products used to build 3,350 homes.

Project Highlights

Good Neighbor Agreement

Together, the CSFS and the USFS are using other tools such as the Good Neighbor Authority to perform watershed restoration and forest management services on National Forest System lands. A Master Good Neighbor Agreement, signed by both agencies last November, fosters a collaborative approach and leverages state resources to accomplish work across land ownership boundaries onto National Forest System lands.

Both agencies are working to identify eligible projects to protect water supplies, manage insect infestations, reduce wildfire risk and meet other forest management objectives.

For the 2015 Aerial Detection Survey highlights and maps, visit: