From his seat in a small plane, Dan West can spot what most people miss as he surveys the trees across Colorado’s 24 million forested acres. Every summer for the past 11 years, the entomologist for Colorado State Forest Service has traced the patchwork of colors looking for clues of stress, like drought and beetle kill.
And this year, the view in some places is a little brown around the edges, even as some pockets of the state are rendered in vibrant yellow and orange.
A dismal snowpack followed by a warm spring with short bursts of precipitation put the aspens and other trees in distress, dimming the glow of Colorado’s seasonal color show in many parts of the state.
“It’s no different than your house plant. If you didn’t water your house plant, the edges of the leaves will start to turn brown and eventually the interior of that leaf will kind of turn a little bit yellow and that’s because it doesn’t have enough resources to keep that chlorophyll getting back into the leaf,” West said. “The same thing happens in aspens when we’re in these drought conditions.”
The aerial surveys offer a clearer picture of how Colorado’s trees are faring, plus a data-driven forecast for one of the state’s most beloved seasons.
“What can change year to year is the soil moisture going into that summer season,” West said. “Every year, the amount of pigment that’s in those leaves can change just a little bit based on the condition of the aspen going into the summer.”
He called this year’s foliage a “mixed bag,” with golden yellows and vibrant oranges showing up in many parts of the state, but more brown and crispy leaves in drier areas.
If there’s enough sugar trapped in the leaves, some will turn a purplish-red. This year, that wasn’t the case for many aspen strands because the trees were stressed for water and struggling to keep the metabolic process going, West said.
Farther west, where the extreme drought conditions persisted through the summer, more leaves have browned edges.
Aside from a shift in colors, the drought also strips evergreen trees of their defense against bark beetles, which live and feed below tree’s bark, West said.
“They basically take that water, turn it into resin, and then any bark beetle that’s trying to get into the tree, they’re able to push that bark beetle out with the resin,” West said. “They have some kind of chemical warfare in that resin, where they’re making it toxic to these bark beetles. But at any rate, without the water, trees can’t defend themselves.”
Reddish hues in ponderosa pines, especially along the Front Range, are signs that the trees are struggling, he said.
“If you’ve driven I-70 or if you’ve driven down 285, mountain pine beetle is rearing its ugly head once again,” West said.
“Somebody called me that was from out of state and said, ‘Oh man, I love how your conifers are turning this red-brown.’ I was like, ‘I’m sorry, but we don’t love it. That means the tree’s gonna die.’”
From the sky, West is looking for fading trees and marking on a tablet the ones he sees have turned green from last summer to a rusty-brown color — an indication that the bark beetles are sucking the water and nutrients from the trees.
“And we can see that from the aircraft really plain as day,” he said.
Most years, he tries to fly early enough that he can see the forest before the beetles emerge and start to attack the healthy green trees. But this year, pauses in federal funding and an early retirement program offered to federal workers that led to a shortage in pilots, put a big delay on the aerial surveys.
“We’ll probably be flying all the way through about Oct.17 when maybe a lot of our mountain peaks are obscured by snow and we just can’t see tree canopies,” West said.
“This is the magical window”
Incoming cold weather and snow that has already blanketed higher elevations in some parts of the state could mean an earlier-than-expected end for peak colors. West recommends getting outside now.
The Colorado Department of Transportation is advising those traveling to see the fall colors to be aware of long delays along Interstate 70 and U.S. 285, especially between South Park and Denver as people head to Kenosha Pass.
Based on data from the same weekend last year, peak volumes at the Eisenhower Johnson Memorial Tunnels hit nearly 3,000 cars per hour at noon on Sunday, CDOT said. The long return home for mountain travelers headed eastbound went well past 10 p.m., the department said.
When leaf peeping, CDOT recommends leaving early or late in the day to avoid the worst congestion. To stay safe, find designated areas to park, be aware of pedestrians outside of their car taking photos and be aware of cars traveling at lower speeds.
This weekend, the higher peaks along most of I-70, and some of the cooler valleys, will have a great show of colors, West said. Spots along U.S. 285 through the central portions of the state will also have great displays this weekend and next, he said.
He also recommends leaf peeping in Breckenridge and towns with similar elevations, like Frisco and Silverthorne.
“Now is the time to make a picnic, grab your sweetie, grab your dog, grab your loved ones, and go for a drive and spend time in the mountains right now,” he said.
“This is the magical window before the snow kind of pushes us out and we start thinking about snow shoes and snow sports and all the ski stuff that we all love to do.”