834 million dead trees put Colorado in danger of disaster

Colorado’s forests are a living graveyard where 834 million dead linger among the survivors.

Death’s growing share makes up 1 in 15 standing trees on Colorado’s 24.4 million forested acres, a testament to the lethal whirlwind of overpopulation and the forces of nature.

Death is a part of life. But not like this.

The influence of the lingering dead — the product of decades of misguided forest management — trickles down to nearly every Colorado resident. It puts the state in the crosshairs of devastating wildfire and compromises the delicate relationship between forests and the people who rely on them for clean and plentiful water.

The forests that coat Colorado’s western terrain tell a story of loss, both past and future: the High Park Fire and beetle kills, smoky skies and barren branches. But as the dead fall and the young grow stronger, these forests tell a story of hope, too.

You need only look a little closer.

‘A tremendous problem’

From 1,000 feet above the forest floor, Dan West can pick out a single tree in a stand of 50. He can see aspens trembling in the breeze under a shock of golden sunlight. Rows of gnawed pine carcasses. A wall of granite bolting toward the windshield of a tiny fixed-wing airplane breaking all the rules of aviation.

Soaring above every acre of Colorado's forests in daredevil aircraft is "a little scary at times, I'm not gonna lie," said West, Colorado State Forest Service entomologist. He spends his summers in the sky tracking the annual migration of tree pests.

On those feverish flights, West marvels at forests mauled by bark-eaters like the mountain pine beetle and spruce beetle, which have infested more than 20 percent of Colorado’s forests in the last 20 years.

But West doesn’t blame beetles alone for the state of Colorado's forests. The roots of today’s problems trace back to the early 1900s, when the commercial timber industry was booming and forest fires were blackening millions of acres across the West.

A newborn federal agency called the U.S. Forest Service started funneling resources into fighting those fires. 

In 1935, the forest service’s “10 a.m. rule” mandated that all fires be suppressed by 10 a.m. the day after the initial report. In 1944, the forest service introduced Smokey the Bear as the huggable face of fire prevention.

Those well-intended efforts would eventually set up Colorado for huge wildfires like the High Park Fire, which burned more than 87,000 acres and 259 homes west of Fort Collins in 2012.

Forests need fire. The flames thin out overgrown stands, making room for younger trees to grow and regenerate forests.

Removing wildfire from the equation left Colorado forests with a monoculture: Thick, overgrown stands of trees that are the same species, size and age. Some low-elevation ponderosa pine forests have 100 trees per acre where there should be 40, forcing the trees to compete with their neighbors for resources. 

Enter bark beetles, which West calls “the sanitizers of the forest." The bugs are a sort of Lysol spray that scrub away the weak, the diseased and the lightning-damaged. Add a dash of bark beetles to overpopulated forests, though, and you end up with an all-you-can-eat beetle buffet.

“You throw on top of that a drought, and it allows these bark beetle populations to build up to the point where the trees are basically defenseless,” West said.

Trees protect themselves with resin, a natural armor. Some tree resins wage chemical warfare on insects, while others trap and smother the attackers.

More:Emerald ash borer: Fort Collins ash trees are in trouble. Just ask Boulder.

But trees stressed by drought or facing a swelling army of insects can’t hold out forever. Eventually their defenses fail.

When that happens, bark beetles gnaw a hole in the tree’s inner tissues and have celebratory sex right in the entryway. With plenty of grub and faltering tree defenses, beetles breed en masse and work their way through every large tree in the area before moving on. They leave the small trees behind for the grandkids.

This happened with the mountain pine beetle, which swept across about 3.4 million acres of Colorado forests — 14 percent — between 1996 and 2016. Now it’s happening with the spruce beetle, which infested 1.7 million acres in the same period and has been Colorado’s most-harmful tree pest for five straight years.

West doubts the spruce beetle will ease up anytime soon as Colorado forests continue to face overcrowding and the effects of climate change.

“This is a tremendous problem,” West said of the spruce beetle outbreak. “It has far-reaching impacts, from water quality to recreation opportunities to ecosystem processes — you name it. It’s basically across the entire board of everything we think about in our forest ecosystems, the services they provide.”

One of the biggest looming impacts is Colorado water supply.

Forests encrust the mountain snowpack that feeds so many of Colorado’s rivers, the Poudre, Big Thompson and Colorado among them. The trees soak up moisture, hold snow in their boughs and shield the blanket of flakes on the forest floor. They set the tempo for snowmelt, which sends water gushing down riverbeds and into reservoirs each spring.

Already, scientists believe the timing of snowmelt has jumped back two or three weeks. It’s a seemingly small change, but the reservoirs that store water for Colorado residents depend on slow, measured snowmelt. If the snow melts too fast, reservoirs can’t store all the water, which threatens water shortages.

The other big threat is fire.

Another High Park Fire

Kristin Garrison knows there will be another High Park Fire. Another Beaver Creek. Another Hayman.

She knows that thousands of acres will burn. Smoke will sting nostrils. Rivers will run black.

“The conditions that set up High Park — we have those all along the Front Range,” said Garrison, who specializes in fires and fuels management for the Colorado State Forest Service.

Alive or dead, fuel is fuel. And Colorado’s forests have much too much fuel. They're also victims of drought and rising temperatures.

“You combine all of that, and we’re seeing fire behavior like we haven’t seen before,” Garrison said.

Fire burns more intensely in beetle-killed trees and spreads more rapidly through arrangements of overcrowded stands and large, fallen trees.

Changing fire behavior and the threat of falling trees have chased firefighters off the ground. Out-of-control fires now call for large engine crews, chemical suppressants and air attack. That sounds expensive because it is: The High Park Fire cost $38 million to suppress. The 2016 Beaver Creek Fire cost $30 million. The 2002 Hayman Fire cost more than $100 million.

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Wildfires hurt our water rhythms, too. Intense, take-no-prisoners fires — the kinds of fires we see now because of forest conditions — can make soil hard and impervious, like glass. When rain comes, the water skitters across the ground, eroding banks and flooding rivers. 

Even if the soil doesn’t change, there’s no vegetation to stabilize it. Water rushes toward reservoirs around the state polluted by ash, silt, fine sediments. 

The High Park Fire infamously turned the Poudre River black and primed the canyon for 2013 floods. The 1996 Buffalo Creek Fire, which burned 12,000 acres, triggered floods and contaminated one of Denver's most crucial reservoirs. So did the Hayman Fire, Colorado's biggest wildfire in history at 138,000 acres.

Those fires won't be the last to tamper with land and reservoirs, Garrison said. 

"We live in a fire-dependent environment," she said. "We're not going to stop them from coming in. We have to live with them." 

Counting the trees

Wilfred Previant and his crew of 17 see far more life than death in Colorado's forests.

Previant is in charge of the forest inventory analysis for Colorado, basically a tree census run by the U.S. Forest Service. Each summer, crew members trek across 450 three-mile plots and make note of every tree inside. 

In all, nearly 11.7 billion trees survive in the state's forests.

Mortality is normal, Previant said. Some trees have to die so the rest can live. 

Modern forest management revolves around that principle: Remove trees where it’s feasible and financially possible to do so. Let fires burn when you can. Start some yourself — in a controlled environment, carried out by professionals, that is. Let the beetles take their meals.

But management is complicated and expensive on Colorado’s rocky, high elevation terrain, where it’s hard to maneuver equipment and take the wood somewhere it can be used. Those realities make large-scale management “almost impossible,” West said.

And as more and more people respond to the call of the urban-wildlife interface, craving that gray area between mountaintops and subdivisions, modern fire strategy is becoming easier said than done. You can’t let a fire do whatever it wants when life and property are nearby.

Still, success stories shimmer on Colorado’s tree-lined horizons. In the last decade, the U.S. Forest Service and Colorado State Forest Service have treated more than 850,000 acres of forestland by thinning overcrowded stands and carrying out prescribed burns, among other methods.

Ample moisture in 2011 helped dwindling pine trees fight back against mountain pine beetles with their resins, forcing the insects to retreat. Garrison sees more and more landowners hardening their homes against wildfire and removing flammable vegetation that could allow wildfires to spread. Grasses and plants are poking through the charred landscape of the High Park burn area, holding the soil steady.  Water providers are teaming up with state and federal agencies to fund management efforts.

It’s easy to paint fires and insects as villains, assign them evil archetypes and blame them for the downfall of our forests. West, the entomologist, tries to remind people that change isn’t always bad.

“I try to look at it as regeneration,” he said. “Some of these bark beetles are here because the ecosystem was out of balance. They can regenerate the forest and allow younger trees to grow up through the forest canopy.”

Before, those young trees vied for sunlight and nutrients beneath the oppressive cape of their elders. Now, they have space to grow.

What’s unclear now is what they’ll grow into, and when. The truth is, this story has no ending. The next chapter of Colorado’s forests hasn’t been written yet.

We don’t know how droughts will play out, or exactly how much temperatures will increase. We don’t know how our water systems will respond to changing hydrology fueled in part by forests. We don’t know when the next big fire will come, or the next brutal insect.

But “forests are pretty resilient,” Previant said. “They’ll adapt to the situation. Whether it’s good for us, that’s an open question.”

Colorado forests by the numbers

Dead standing trees: 834 million on “true forestland” — parcels 1 acre or larger with at least 10 percent tree cover

Increase in dead standing trees between 2010 and 2016: 30 percent

Live trees: 11.67 billion on true forestland

Forested acres in Colorado: 24.4 million

Acres infested by mountain pine beetle and spruce beetle, 1996-2016: More than 5 million

Source: Colorado State Forest Service