On the south side of the Chautauqua Auditorium, 12th Street turns into a dirt road that meanders up towards the base of Green Mountain. Called the Enchanted Mesa trail, the wide path allows groups to walk several abreast — or one dog the space to frantically sniff to the limits of its leash without tangling itself in the underbrush. 

This summer, however, hikers and dogs should heed their surroundings on this path, as trucks belonging to Boulder’s Open Space and Mountain Parks drive up and down, carrying away logs that stood just days before as members of the Front Range arboretum.

Covering 90 acres from the south side of Chautauqua to the land above the  National Institute of Standards and Technology (NIST) campus, the Enchanted Mesa thinning project is aimed at reducing the threat of intense fire while working to restore the health of the forest.

Chris Wanner, the City of Boulder’s vegetation stewardship senior manager who oversees the project, met me at the picnic tables behind the auditorium. Wearing a sun-bleached, sweat-stained City of Boulder hat, Wanner acted as a guide to show me the project area and answer excessive questions along the way. 

As we covered the first straightaway, heading towards where the road turns left and gains altitude, Wanner explained that deciding where such projects are implemented is a project in itself: Where is the forest most in need of care? Where would a fire prove most problematic? “Where those things align is what we’re shooting for,” he said. 

The top of Enchanted Mesa, approaching the worksite. Credit: Tim Drugan

A road, like the one we were walking on, helps guide such decisions. I mentioned to Wanner that on a recent hike behind NCAR, I’d noticed dense groves of trees with overgrown vegetation in their understory, which would seem to provide a foothold for fire should sparks land nearby. Wanner nodded, but explained that getting thinning machinery into such a rugged area would be difficult if not impossible.

“You could do helicopter logging or something like that, but then you’d need a helicopter, and the infrastructure to support it,” he said. “You’d need big trucks coming in to haul away the lumber, which means roads. It’s a balancing act of what is realistically operational — and if you’re talking helicopter logging, you’re exponentially increasing the cost of all those operations too.” 

Helicopters, it seems, aren’t cheap. 

As though to illustrate the comparative ease of access for the worksite we were meandering towards, a city truck passed us, driven by a young man in aviator sunglasses who stopped to offer hellos. Behind his truck rattled an empty trailer that bounced over divots carved by rainwater in the road. Not before the rattling disappeared up the path, Wanner and I stepped aside for another truck, this one filled with young men on their way to fell the trees that would fill the trailer up ahead.

When we were alone again, Wanner gestured to the hillside to our right to show an area the thinning crew had already moved through. Ponderosa pines grew with gaps between trees, yet undergrowth was already sprouting in the spaces between. “This is green ash,” Wanner said, pulling on the leaves of one of the saplings. “They reproduce asexually so they can sprout right out of old roots.”

Green ash removal had prompted some outcry among those living nearby when thinning crews worked close to houses by Chautauqua. Impacted by Emerald Ash Borer, an invasive insect from northeastern Asia, most of the green ash by Chautauqua are either dying or dead, leaving an expanse of bony branches rising above the canopy. 

“[Green ash] is a nice shade tree,” Wanner said. “But when you’ve got Emerald Ash Borer running through it, they’re all gonna die.”

And dead trees offer themselves as ready fuel to fire. To mitigate this risk, Wanner and his team worked along where houses met the swath of retired flora.

Dead Green Ash not yet cleared. Credit: Tim Drugan

“We were working to build a buffer between the fuels and the houses,” Wanner said. “One of the concerns we ran into was it was so dramatic. People were used to having this cover in the area, so [the thinning] came as a bit of a shock.”

Wanner said complaint calls ranged from “I’ve been hiking this trail for 30 years and I don’t want it to change,” to “You’re taking away my favorite tree.” But he also said perspectives are shifting after the Marshall and NCAR fires. Now he’s getting just as many calls from residents demanding to know when the city is going to come clean up flammable material. 

“People are starting to understand that forests are overgrown and denser than they should be,” Wanner said.

As the already-sprouting thinned area showed, such efforts are not a one-and-done solution. Where fire used to burn periodically, keeping the ecosystem in equilibrium is something that must be viewed as “ongoing maintenance.”

“It’s never going to be done,” Wanner said. “Ideally, we’d use fire as a maintenance tool, but that’s not always practical or feasible.”

Proximity to town means a runaway prescribed burn could quickly jump from the forest to neighborhoods. So until the practice is more refined — if fire ever lets itself be controlled — repeated mechanical thinning can provide some of the benefits of a burn without the risk.

The active forest thinning worksite. Dense stands of ponderosa pines are not just a fire risk, but are unnatural to that ecosystem. Credit: Tim Drugan

Thinking like fire

As the vegetation steward, Wanner and his team are not concerned solely with fire mitigation. Much overlap exists, but there are practices Wanner prescribes that would not be employed by one whose only goal was fire reduction.

One example came into view as the road leveled out near the top of Enchanted Mesa. A ponderosa pine stood beside the road, relieved of its branches: a skeleton forced into its current state ahead of its time. 

In a landscape where fire burns regularly, many snags (standing dead trees) are left in flames’ wake. Snags rot from the inside out, providing homes to cavity nesters such as insects, birds, bats and rodents. When fire has been taken from the system, however, such dwellings aren’t readily available. Wanner and his team therefore deliberately girdle trees — chipping away the bark around the tree’s base, causing it to die over time — and cut away limbs to add real estate to the forest’s tight housing market. 

“It’s like these cool little condos in the forest for wildlife,” Wanner said before turning to continue up the road.

A log left on the landscape: another possible home for critters. Credit: Tim Drugan

Not far from the manufactured snag, Wanner and I came upon the first active forest thinning worksite. The truck with the attached trailer that previously passed us was parked beside a pile of ponderosa pines. With their limbs removed, the evergreens morphed from stately trees into lowly logs. The diameter of these logs ranged from eight to twelve inches.  

“It’s usually the same structure in most of our stands,” Wanner said when I asked him about the similar size. “You’ve got this point in time where fire was taken out of the system, so you’ve got all these trees that are about 100 years old. And that’s where the density sort of shifted.”

Wanner explained that despite what the pile might show, his team was not only taking young trees, though that was a significant portion because of the boom in growth from roughly a century ago. 

“The focus is creating more diversity in size classes,” Wanner said. “You want the younger ones growing and filling in, replacing the older ones as they die.”

Logs waiting to be removed from the landscape. Credit: Tim Drugan

Such is a key difference between commercial logging and ecologically-minded thinning. When logging for profit, the biggest trees bring the biggest payday. With thinning, however, ecologists don’t remove big trees en masse due to their important niche role in the ecosystem. As was the case with the manufactured snag, Wanner and his team are trying to think like fire, not capitalists.

The two sides of the road where we stood offered a contrast between a thinned landscape and one where no action but fire suppression had been taken. The thinned area offered sunlight a path to the ground with ample space between clusters of trees — parklike, as ponderosa pine forests are meant to be. The unthinned side looked a mess: trees competing for sun that struggled to make it through the choked canopy, underbrush rising about the plethora of trunks.

Keeping Nutrients on the Landscape

A drawback of mechanical thinning, when compared to fire, is the removal of nutrients from the ecosystem. When a tree burns, the ash released nurtures future flora. Mechanical thinning, however, takes felled logs out of the forest and their nutrients with them. This is necessary, if not ideal, because if logs are left where they’re cut, dried-out fibers offer themselves as willing accomplices to flame. “If we just left the trees on the ground, we wouldn’t be reducing the fuel load, we’d just be rearranging it,” Wanner said.

To offset some of this nutrient loss, branches and smaller pieces of trees are put through a chipper that sprays wood-chips back from whence they came: a taxing process, according to crew member Logan Keebler.

“Most of the time we’re cutting down trees,” Keebler said. “Which is by far the best part of the job. Chipping isn’t the worst, but it’s arduous.”

A demonstration of this chipping, and other thinning deeds by the forest restoration crew came into view up the road. A man with a Tom Selleck mustache downed a tree while others shoved previously cleared slash (material taken off the logs such as twigs and branches) into a chipper. Another mustachioed man approached us to chat with Wanner and wrap a hand around mine that was thick with muscle and calluses.

Ben Cook (left) talks to Chris Wanner (right). Credit: Tim Drugan

Ben Cook, one of two restoration crew leads, wore a shirt darkened by sweat and chaps to protect his legs from unruly chainsaw blades. Speaking over the noise of the chipper, he said he got into the job through other work in a similar vein. Growing up working in mills, he’d also worked as a commercial fisherman, though decided that he couldn’t continue year-round, as “winter fishing is absolutely miserable.” Instead he decided to cut trees, in the winter, in Minnesota.

Behind Cook, who spoke with Wanner about the crew’s plan for the rest of the day, the chipper coughed out tree after tree as men with chainsaws worked through a thicket of young ponderosa pines. 

“It’s a hard job,” Wanner said in response to my observation about the seeming brutality of the work. “It’s hot, you’re covering a lot of ground with heavy tools. It’s a young man’s game.”

Despite the hazards, Wanner said his crew had thus far avoided serious injuries or accidents, “knock on wood.” What plagued them was the usual muscle strains and overuse pains known to all those in manual labor.

We walked back to Chautauqua along the Mesa Trail before turning down Bluebell Road. To our right, I noticed trees and bushes growing up against the cabins and houses that bordered the park. After speaking to Jim Webster of Wildfire Partners, I was fairly certain this was a fire hazard, and one right up against open space. I pointed out the brush to Wanner. He sighed.

“There’s only so much you can do on the open space side,” Wanner said. “If you have trees growing right up against your house, well …” He shook his head.

Tim Drugan

Tim Drugan covers wildfires, water and other climate change-related issues for Boulder Reporting Lab with a focus on explanatory and solutions journalism. He also is the lead writer of BRL Today, our morning newsletter. Tim grew up in New Hampshire and graduated from UNH with a degree in English/Journalism.

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