As conservationists and forestry experts keep a close eye on Aspen-area avalanche pathway bottoms marred by large stacks of downed trees, the question of how to combat a potential spruce beetle outbreak arises.
The short answer: Not much can be done. Nature will have to run its course.
And that could mean the devastation of large swaths of Engelmann spruce forest on Independence Pass and elsewhere in the region sometime in the next three to 10 years, should the destructive beetles jump on the opportunity to breed inside the freshly-dead timber.
“It’s a natural phenomenon,” said Karin Teague, executive director of the Independence Pass Foundation. “There is such an enormous volume of downed trees all over, not only all over the pass but all over the region. It can’t possibly be cleared. It’s an impossible task.”
Clearing the trees closest to Highway 82 on the pass may seem doable, but observers note there are countless other piles of avalanche-felled spruce on U.S. Forest Service property deemed inaccessible to the types of vehicles that would be needed for the job.
Nor can the beetle breeding be offset by controlled burns, said Adam McCurdy, forest programs director for the Aspen Center for Environmental Studies. Dead spruce trees burn too slowly.
“The challenge is, the spruce forest does not burn easily,” McCurdy said. “You’d have to have pretty exceptional conditions to get fires going in those areas. The dead trees are on the ground, soaking up water. Even if you had conditions where they were able to burn, it would be too hard to control.”
While the most recent winter and spring snowfall was regarded as above average, the avalanche activity in the Aspen area was viewed as exceptional: perhaps a 1-in-300-year event, according to estimates in some areas.
The downed trees, coupled with climate change and warmer overall temperatures conducive to beetle activity, resulted in what experts are calling a “recipe” for a spruce beetle outbreak.
The beetles have been wreaking havoc north and south of the Roaring Fork Valley. They’ve already devastated large sections of the San Juan and Sangre de Cristo mountains, as well as areas around Rocky Mountain National Park.
They already exist in Pitkin and Lake counties, but as of now, their populations aren’t threatening. The fear is that the dead timber created by avalanches will become a breeding ground for the tree killers, giving them the numbers to either wipe out, or thin out, the area’s high-country spruce forests.
Jason Sibold, assistant professor of geography at Colorado State University and a forest specialist, said that trying to remove, burn or spray the trees could be disastrous on many levels.
Backcountry areas would be negatively impacted by such efforts. Then there’s the risk that the large number of workers, volunteers and equipment required to do the job would introduce invasive or nonnative species to the area, he said.
Sibold is planning to visit Independence Pass sometime in the next couple of months to see if beetle activity appears to be ramping up.
“It would be a massive undertaking,” he said of potential projects to keep the beetles in check. “I couldn’t even imagine the cost. The scale makes it impossible.”
Another method to fight a beetle outbreak would be peeling back the bark and exposing the destructive insects, rendering them harmless, given that they need the bark’s protection. But a large-scale peeling project also would be a gigantic and expensive undertaking.
“You want to avoid a knee-jerk reaction,” Sibold said. “It might not be effective. It might only delay an outbreak.”
So, the proper course of action might be to remain passive, to watch and wait and study.
Sibold said he spoke with Teague and McCurdy about conducting more research to see if the local spruce forests are producing seed. Spruce trees are conservative and grow slowly, and a project to help the forest along by planting more seedlings could bolster their numbers, perhaps lessening the impact of a beetle outbreak.
“We should collect information to see if we need more plantings,” Sibold said. “We may need to spend a few hundred-thousand dollars to become more knowledgeable.”
On the positive side, the Aspen-area forests have a history of resilience, largely because of their diversity, McCurdy pointed out. A pine-beetle outbreak in the valley in the early 2000s caused damage, but it could’ve been far worse.
The diverse nature of Aspen-area forests may end up keeping the spruce beetles from doing the kind of damage they’ve done in parts of the San Juans that have experienced more than 90 percent beetle kill, Sibold said.
McCurdy said past research supports the notion that, in the last two centuries, the spruce forests along the pass have not experienced a widespread spruce beetle outbreak.
Teague also recalled the relatively recent pine beetle problem.
“The pine beetle kind of came, and did its thing, and thinned out the forest a bit from some of the old trees, and now that phenomenon is largely finished for the time being,” she said.
“I think we can maybe expect the same of the spruce beetle. It could feel pretty devastating for some period of time, but it is natural and we do have a diversity of species that will help maintain a healthier forest, generally,” Teague added.