OURAY – As winter’s snows recede, Ouray locals have been dismayed to discover increased numbers of dead and dying fir trees on the steeply forested mountainsides that ring the town.
The culprit is a bug known the fir engraver beetle, U.S. Forest Service Forester-Silviculturist Todd Gardiner of the Ouray and Norwood Ranger Districts told the Ouray City Council at its meeting on Monday, May 6.
The insects are specific to the species of white fir that grows in this area, and are only 1/10th of an inch in size. They bore through the bark and feed in the cambium layer of the tree between the bark and the wood. Once established, the beetles create egg galleries that eventually girdle a tree so that water and nutrients can’t flow properly to its upper reaches, and the tree dies.
Although fir engraver beetles are not as aggressive as the spruce beetle and mountain pine beetle that are attacking huge swaths of densely forested terrain on Wolf Creek Pass and the Front Range, increasingly warmer and drier climate conditions around Ouray have lately helped the tiny bugs to thrive and multiply here.
“We have built to an epidemic number where they are starting to be more aggressive than we would typically see in this insect,” Gardiner said.
The bugs have been attacking the tops of trees in the area for a number of years, but the problem has lately gotten dramatically worse, with a big increase in dead trees just since last fall. Come July and August, the beetles will fly out of those trees, and move into new ones, starting the cycle all over again.
“Next winter will see the next round of dead trees,” Gardiner said. “A lot of trees don’t know they are dead yet.”
Foresters have been closely observing a stand of white fir trees in the USFS-managed Amphitheater Campground near Ouray since mid 1990s, where they noted a prevalence of root disease and western spruce budworm that makes the trees even more vulnerable to beetle infestation.
Hoping to stem the problem, last summer Forest Service workers cut down 150 trees in a 16-acre area around the campground. But Gardiner said, it hasn’t been enough to make a difference, even in this small, easily managed area.
This underscores the challenges of trying to manage the infestation on a forest-wide scale.
The tiny beetles have proven to be tough adversaries on many levels. One problem is that they first attack the tops of the trees, which makes pesticide application difficult – particularly in steeply forested mountainous terrain such as that which surrounds Ouray.
This year’s lower than average snowpack (currently hovering around 70 percent on Red Mountain Pass) “is not helping things,” for the drought-stressed trees, Gardiner added.
While the fir engraver beetle is a significant threat to forests around Ouray, Gardiner said that on a grander scale, the spruce beetle presents an even bigger threat to the landscape, because so much of Colorado’s mountains are covered in Engelmann spruce.
“There is an epidemic of spruce beetles in surrounding areas,” he said. “You could expect to see dramatic changes to our landscape in the coming years.”
USFS personnel overseeing the Grand Mesa, Uncompahgre and Gunnison (GMUG) National Forests are currently conducting a forest-wide assessment to try to address the problem through sanitation and salvage – harvesting infested trees when possible.
“This is the best way to stay ahead of bugs,” said Gardiner.
But unfortunately, harvesting the hundreds of infested trees on the mountains around Ouray is simply not a realistic option. “It’s so tough, around Ouray, with steep slopes, inoperable ground and complex ownership issues,” he explained.
Sustained cold winter temperatures could kill off the infestation. But with average winter temperatures in the area only getting warmer, Gardiner foresees no help there.
In the end, it appears that not much can be done to stop the beetles’ onslaught. “What you see this year will keep happening, unless something happens with precipitation and the drought cycle,” Gardiner predicted.
In the short term at least, that’s not likely. The outlook for the next three months is for below-average precipitation and above-average temperatures.
“I kept waiting for a ray of hope but it seems like what you are saying is it’s just going to get worse,” Councilor Michael Underwood lamented. “Are we really saying it’s impossible to deal with?”
“It’s darn near impossible,” Gardiner said. “I’m sorry I couldn’t paint a rosier picture.”
email@example.com, or Tweet @iamsamwright