Response Plan to Combat Spruce Beetle, SAD Being Drafted
by Gus Jarvis
Dec 05, 2013 | 1810 views | 0 0 comments | 33 33 recommendations | email to a friend | print

MONTROSE – As tens of thousands of acres of forest lands located in the Grand Mesa, Uncompahgre and Gunnison National Forests experience rising levels of mortality due to the spread of spruce beetles and disease, the U.S. Forest Service’s plan to strengthen the the health of the forest is moving forward.

In Montrose this week, regional stakeholders got a glimpse of the severity of Sudden Aspen Decline and the spruce beetle infestation problem on the GMUG. A new plan promoting recovery and improving the resiliency of healthy tree stands was unveiled. Its goal: to help threatened trees and tree stands bounce back more quickly from future epidemics.

Across the entire GMUG, which is comprised of more than three million acres of diverse vegetation, with approximately 140,000 acres of spruce-fir and 145,000 acres of aspen, forests have experienced mortality from insects and diseases over the past decade. Based on patterns of bark beetle kill that have taken hold in adjacent forests, Forest Service officials expect the mortality of trees on the GMUG to rapidly increase in the future.

The Forest Service issued a formal statement of intent to prepare an environmental impact statement for its “Spruce Beetle Epidemic and Aspen Decline Management Response” plan in July. The plan will direct treatment of the affected lands and threatened trees and tree stands at risk of large-scale epidemics, with the added goal of reducing the threat of large-scale wildfires.

Following the midsummer announcement, comments concerning the scope of the project were heard by the agency until the end of August. A draft of the environmental impact statement for the plan is expected next summer. It will be released for a 45-day comment period.

Tuesday’s daylong public meeting at the Holiday Inn in Montrose, hosted by the Western Colorado Landscape Collaborative, offered stakeholders and members of the public a chance to learn more about the Forest Service’s proposed plan and to begin discussions on it as the agency works toward drafting its environmental impact statement.


‘They Make a Living by Killing Trees’

For the past decade, according to Forest Service Entomologist Tom Eager, an ongoing spruce beetle epidemic has been spreading across the San Juan and Rio Grande National Forests. That epidemic is now moving north, and impacting large portions of the GMUG. Based on aerial survey data from 2012, approximately 311,000 acres of spruce beetle activity are now identified in Colorado, with roughly 85,000 affected acres on the GMUG.

“We had field crews out this year and found some active spots pretty much on the southern margin of the GMUG, but the Uncompahgre Plateau is seeing some spruce beetle activity as well,” Eager said.

Spruce beetles are native to Colorado, Eager said. The tiny insects appear mostly in small numbers, feeding on blown-down trees and branches. Every now and then, there are large, dramatic wind events that blow down large swaths of trees. Those blown trees “are basically free food” for the beetles, Eager said, that make it possible for large numbers of beetles to build up and reach a critical mass.

“A great majority of beetle outbreaks were originally started by weather disturbance types of events,” Eager said.

Spruce beetles (Dendroctonus rufipennis) are about the size of a grain of rice. In stands of spruce trees, the beetles emerge from their host tree and fly in the spring – from as early as May to as late as July – to find a new host tree and attack it. The trees try to fend off the beetles using their natural defenses, but the beetles employ pheromones to attract other beetles to stage mass attacks. After the attack, beetle larvae feed on the tree throughout the summer and into winter. In two years’ time, the beetle pupae emerge from the tree, and fly off to find a new host.

“They make a living by killing trees,” Eager said of the tiny insects. It’s difficult to know when a spruce tree has been infected. Unlike the signature of pine beetles – they leave behind an infested tree that turns red fairly quickly – the mark of the spruce beetle is not immediately  apparent. Even while infested, trees affected by spruce beetles may not show it initially.

Then, “after the beetle has gone through almost the full two-year cycle, the needles rain out of the trees,” Eager said. 

“What does the future hold on the GMUG? The probability of this just going away, with winter weather, doesn’t happen that often. Most of the time, the beetles do their thing.”

While the spruce beetle epidemic continues to spread, warmer temperatures have caused aspen stands throughout the state to deteriorate. Stand-level episodes of aspen mortality have always occurred over time, but the speed, severity, landscape scale and causes of aspen mortality over the past decade have been so notable that the U.S. Forest service has labeled this  new disease Sudden Aspen Decline.

Because aspen trees in drier locations are more at risk for SAD, the recent hot and dry climate patterns, according to the Forest Service, have led to 1,21500 acres affected by SAD in Colorado. Approximately 238,000 of the affected acres of aspen are in the GMUG. Like the spruce beetle epidemic, Forest Service officials believe recurring drought and high summer temperatures will exacerbate SAD.

“Here in the southern Rocky Mountains, we have been hit pretty hard by it,” said Forest Service Plant Pathologist Jim Worrall, adding that a drying trend that lasted up until the mid 1980s helped SAD develop. “What is going on now? The good news is that since 2009, there haven’t been any new affected areas. The climate has moderated. However, the previously affected stands have continued to deteriorate.

“It’s not all grim; there are things we can do to do some triage here,” Worrall continued. “There are management approaches that can increase the resilience of aspen to aid the recovery of aspen.”


Getting Back to Forestry

To make for healthier stands, the plan calls for the recovery of dead and dying tree material.

To enhance resiliency, treatments in live stands would increase age class and species diversity and in doing so, create healthier conditions of spruce-fir and healthy clones of aspen.

For aspen stands in which less than a 50 percent root system has been affected by SAD, the “Spruce Beetle Epidemic and Aspen Decline Management Response” plan would make those stands candidates for aspen regeneration treatments. As for tree stands already dying because of the spruce beetle, the plan will outline the removal of dead and dying trees. In stands threatened by the beetle outbreak, forest resiliency will be improved by reducing stand densities, and by promoting multi-storied stand structure.

According to the notice of intent, the project will define opportunity areas available for treatments, priorities for treatment, parameters and design features, operating protocols, monitoring, and activity tracking.

Both commercial harvest and non-commercial treatments (mechanical and prescribed fire) may be management tools for use in 250,000 to 350,000 acres. Approximately 118,000 acres of spruce-fir and 140,000 acres of aspen would be analyzed for potential commercial and non-commercial treatments.

An additional 60,000 acres of aspen outside of lynx habitat would be analyzed for recovery and resiliency treatments as well.

The plan estimates a range of 4,000 to 6,000 acres of commercial harvest treatments would occur annually, for a total 40,000 to 60,000 acres over the life of the 10-year project.

“The impacts on the local economies here could be pretty big,” Eager said. “There is a lot of material out there.”

Another 3,000 to 6,000 acres of non-commercial (mechanical and prescribed fire) treatments could also occur, should funding be available.

“We are getting back into the whole forestry picture,” Eager said. “We are going to go into places, removing trees, getting product, getting some of those [product] funds to collect seeds, send them to the nursery and eventually spread out the age class of spruce trees.”

For more information on the Forest Service’s intent to draft the environmental impact statement, visit

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