They sent crews and a single engine air tanker, but when the temperature and winds rose, the fire took off fast. At 3:12 p.m. the city ordered mandatory evacuations for more than 3,000 homes—less than 10 percent of the total they would evacuate in the coming days. That afternoon the City of Colorado Springs closed its iconic Garden of the Gods park for the first time since 1901. The fire burned downhill toward developments that night, traveling as much as half a mile in an hour and growing to nearly 2,000 acres in size. After midnight authorities went door-to-door to evacuate residents of Manitou Springs, a historic enclave of tourists and artists, in hopes of getting everybody out by dawn. They didn’t finish the evacuation until about 9 a.m., when the fire was barely a quarter mile away.
The fire outside Colorado Springs, one of 16 large fires burning out of control across the country, was the top firefighting priority in the United States almost as soon as it ignited. Between all of Colorado’s fires, the $6 million in emergency firefighting funds the governor released Friday was all but gone by the time the weekend was over.
CLIMATE, HOUSES, POWER LINES, OIL PADS, and even marijuana operations and meth labs hidden in the woods all brought more wildfire to Colorado. But another change in the forest had also turned millions of acres of pines red, though not with flames.
Since the late 1990s an outbreak of the mountain pine beetle, a pest the size of a match head, had devastated more than 107,000 square miles of forest in the United States and Canada—an area larger than the entire state of Colorado. In British Columbia the pest killed more than half the commercially valuable pines in less than 20 years. The beetle is a native of the West, and it breaks out in regular cycles, but the outbreak that began in the late 1990s was 10 times larger than any other on record.
The beetles use a pheromone to call an army of insects to an individual tree and then burrow inside. They carry a fungus in their mouths that, along with the beetles’ tunnels, blocks the tree’s circulatory system and kills it. Trees can push the beetles out with resin, but when weakened by drought, they can’t produce enough sap to defend themselves. As they die, their needles turn red. Entire mountainsides turn a rusty crimson, then transform into gray “ghost forests” after the needles fall off.
While it was the great lodgepole pine forests of the Rocky Mountains that the pest devoured in the most recent outbreak, it also infests many other evergreens. The effects of the tiny insects’ destruction cascade through ecosystems. The beetles have so devastated whitebark pine forests around Yellowstone that at the end of 2011, the Ninth Circuit Court of Appeals put grizzly bears, for which the whitebark’s cones are a critical food source, back on the endangered species list just four years after the U.S. Fish and Wildlife Service had taken them off.10
In 2012, as the march of the pine beetle slowed (the insects were running out of mature lodgepole pines to eat), the spruce beetle infested a million acres of Colorado’s high-elevation spruce forests.
As the High Park Fire burned into forests of beetle-killed timber, the debate about the impact of those dead and dying trees on fire behavior also grew heated. By 2012 at least 39 separate studies had looked at how the millions of beetle-killed trees influenced the behavior of wildfires, but there was no clear picture of how they would burn.11 I hiked over mountains covered in trees that seemed color-coded for fire, which was how the best-known early hypothesis saw them: When the trees were in the red phase—dead but still holding rust-colored needles—they would be prone to severe crown fires that would burn hotter and faster than in a green forest. But in the gray phase, when all the needles had fallen, fires would have difficulty moving through the crowns and calm down.
A study led by Matt Jolly at the U.S. Forest Service’s Rocky Mountain Research Station showed that the red, dead needles ignited three times faster than green ones.12 Crown fires in red forests, some firefighters and foresters theorized, would ignite with lower wind speeds and less-dry conditions than in forests unaffected by the beetles. The intensity of the crown fires in beetle-killed forests, other researchers predicted, could launch embers farther, thus spreading fires faster.
Other models showed that dead trees that fall to the ground, along with the increased wind penetration in stands with fewer trees and needles in the canopy, would increase the intensity of ground fires. The hotter fires on the forest floor would drive crown fires to erupt with less wind than they typically require. Researchers also documented beetle kills increasing the temperature on forest floors as more sunlight shined through a thinned canopy.
Some studies confirmed that gray forests with no needles on the trees actually slowed down crown fires.
But four months before the High Park Fire ignited above Fort Collins, a report from the Joint Fire Science Program in Boise, Idaho, argued that neither red nor gray forests would be likely to burn more severely than green forests, largely because the death of the trees reduced the amount of fuel in the canopy.13 The paper also maintained that climate and weather factors, rather than needles and dead trees, drive most wildfires.
In fact, during the three biggest fire years since 2000, including the 2012 season, research showed that fires didn’t burn more in forests infested with mountain pine beetles than in those unaffected by the insects.
Lodgepole pines tend to die in “stand-replacing” events. Wildfires or bugs kill off entire forests every 100 to 300 years. The trees’ cones, sealed tight by resin, release their seeds in response to the heat of a fire, and seedlings flourish in the carbon-rich soils after a burn. So these trees have evolved to encourage fire in order to reproduce. During a hot drought like Colorado’s in 2012, lodgepole forests are prone to burn big, regardless of whether they’re green or red.
In the High Park Fire, however, many firefighters reported seeing crown fires that doubled or tripled their speed and intensity when they came to red, beetle-killed lodgepole pine stands, and they couldn’t care less what scientific models said the fires would do. Kevin Moriarty, a graduate student at Colorado State University, interviewed firefighters on blazes between 2010 and 2012 in northern Colorado. They described fires that launched more embers to start spot fires; ground fires that transitioned much faster into crown fires or did so without the ladder fuels that are usually required to take a fire from the forest floor to the canopy; and fires that raced through red-needled treetops far faster than green ones.
“I saw fire running in spruce beetle kill like it was grass or sagebrush,” Fred Schoeffler, a firefighter from southern Colorado, told me at the Large Fire Conference in Missoula, Montana, where Moriarty described the results of his interviews in 2014.
Nobody disputed, however, that the two things turning western forests red—beetles and wildfires—have a common parent: the climate.
At the University of Colorado’s Biogeography Lab, just a few minutes from my office at the university, I visited Tom Veblen, who for 25 years has studied how insects and fires impact forests around the world. Tom coauthored several of the papers that found little evidence of mountain pine beetles increasing the severity of wildfires, and the lab’s studies of fires in beetle kill during the drought of 2002 showed that they didn’t behave much differently than they did in green forests. He wasn’t, however, quick to dismiss what firefighters and land managers have observed. The science surrounding wildfires, he pointed out, is tangled—although some aspects are quite simple.
“There’s one thing that’s consistent where we’re seeing the increase in wildfire and mountain pine beetle,” he told me. “It’s warmer.”
The only thing known to stop a mountain pine beetle outbreak is prolonged subzero temperatures, which haven’t occurred in a decade in much of the Rockies and western Canada. Climate models predict that those temperatures will become increasingly rare. Trees stressed by drought and heat waves are more susceptible to pests, and the insects thrive in the warmer temperatures. The University of Colorado’s Jeffry Mitton and Scott M. Ferrenberg found that due to the warming climate, mountain pine beet
les in some Colorado forests have started reproducing twice a year, instead of once, leading to an exponential increase in the number of hungry bugs.14
In the end, the greatest risk to firefighters may not be in the red or gray forests today, but decades from now after the beetle-killed trees have fallen to the forest floor and new canopies of pines grow above them. Fires there would be difficult to fight because heavy timber burning on the forest floor would hinder firefighters’ travel through the forest and push crown fires to burn faster and hotter.
WHILE THE DEBATE RAGED about whether beetles had made the High Park Fire hotter and faster, a blaze ignited on the Colorado plains with the help of another pest. But though the Last Chance Fire quickly turned into the fourth-largest conflagration in Colorado history, flames erupting all over the state made the grass fire as easy to ignore as the community it was named for and the invasive grass that helped drive it.
The town of Last Chance was born of the automobile, and killed by it more than once. It was the last chance to gas up on U.S. 36 when that was the main thoroughfare between Kansas and Denver. Thousands of pickups, cattle haulers, and tractor-trailers stopped at the pumps there. But when the construction of Interstate 70 rerouted that steady stream of traffic in the 1960s, it starved the town.
On June 25, 2012—the day the fires ignited from Rocky Mountain National Park to Colorado Springs—Last Chance, population eight, was a graveyard of abandoned, decaying motels and a burned-down service station. Only the recently closed Dairy King, with its custard-yellow walls, showed any of its former flair.
But fuel and the automobile once again put the town on the map. A car traveling on State Highway 71 blew out a tire, and sparks from the rim showered dry grass in a ditch five miles south of town. In just over a day the subsequent blaze burned some 45,000 acres and destroyed 11 structures.
Firefighters blamed triple-digit temperatures, the drought, and high winds for the blaze’s ferocity. Ecologists and ranchers in the area noted another factor. Unlike the massive red forests of beetle-killed trees that are impossible to miss in the mountains, the invasive pest bringing fire to the plains is barely noticeable, even when it spreads out over thousands of acres. It’s just a stalk of grass, but there’s little debate about its relationship with fire.
Since the 1800s cheatgrass, a wispy brome native to Asia, has spread around the world, usually hitching rides in packing materials and grain exports. By 1900 expanding railways had dropped the grass in Washington, Utah, Wyoming, and Colorado.
The weed can germinate at any time of year but usually chooses the fall. While it’s covered in snow during the winter, its roots continue to grow, which allows it to sprout early and “cheat” native vegetation out of moisture and nutrients. It can reach 20 inches tall while native plants are just getting started. Merely two inches of precipitation can drive a strong flush.
But the invasive weed uses some even sneakier tricks to drive out native vegetation. Cheatgrass completes its life cycle quickly, building a prolific seed bank, then drying out while native vegetation is still young. A bloom of cheatgrass can leave nearly 300 pounds of dry fuel per acre for hungry fires.
Bunchgrasses native to the high plains and the Great Basin evolved to hinder the spread of fire. They grow in clumps separated by bare soil and sand. It’s difficult for the flames on one bunch to reach others.
But cheatgrass grows in “continuous fuel beds” that are so thick and even they are often mistaken for Kentucky bluegrass or even fields of wheat. With no natural fuel breaks in the tall, dry grass, fire spreads easily. A 2013 study reported that landscapes infested with cheatgrass are twice as likely to burn as those covered with only native grasses.15
“Cheatgrass was introduced well over 100 years ago, but it . . . didn’t take hold in a very significant way as far as carrying [fire] until about 30 years ago,” Tim Murphy, the assistant director for fire and aviation at the Bureau of Land Management, told me when I visited the National Interagency Fire Center in Boise—America’s Pentagon of wildland fire.
The BLM manages the most land of any federal agency, mostly wild grasslands and scrub, the landscapes where cheatgrass has the most impact. With a neatly trimmed, graying beard and an easy smile, Murphy seemed cheerful as he described the cheatgrass flooding Idaho, Nevada, California, Utah, and, increasingly, Wyoming and Colorado.
“It used to take one hell of a wind to carry a fire,” he told me of the sagebrush steppes where cheatgrass is, literally, spreading like wildfire. “A 30,000-acre fire, . . . you would write home about. Now a 300,000-acre fire is the stepping-off point for comment. Our whole view has changed.”
The blazing cheatgrass kills off the native plants before they mature, preventing them from regenerating and spreading its own abundant seeds. Native vegetation that survives a fire often struggles in the scorched ground—some arid and treeless landscapes take 70 years to recover after they burn. Cheatgrass, however, snaps back quickly.
Fires in native grass landscapes rarely burn more often than every 25 years, and sometimes as infrequently as every 70 years. “It’s down to 10 and even five years in some places” where cheatgrass is present, Murphy told me.
So it’s a vicious, and fiery, cycle—more cheatgrass brings more frequent and larger blazes, and the increase in fires brings more cheatgrass.
The invasive grass has one more advantage, which Tim illustrated with a map of fires along Interstate 84 around Boise. Spreading out from the highway and housing developments was a growing red blotch showing fires. As the weed spreads over the landscape, the sparks people produce where they live, play, and travel—like the Last Chance highway in Colorado—are far more likely to start fires.
Today cheatgrass covers more than 101 million acres of the United States. In 1999 cheatgrass-driven fires burned more than a million acres of the Great Basin in 10 days. The pest infests about 46 million acres of winter wheat annually, which costs growers about $300 million in lost crops and an additional $70 million in herbicides to try to kill it off.16 It dries up too early to be of much value for grazing livestock. And it devastates the habitat of many other animals. The sage grouse is teetering on the brink of threatened species status, in part due to cheatgrass fires burning away its nesting sites in sagebrush.
Bethany Bradley planned to search for extraterrestrials on Mars, but ended up studying aliens on earth. The biogeographer at the University of Massachusetts is one of the leading researchers studying the link between cheatgrass and fire in the American West.
Little green men seem more exciting than a dull green grass, but Bradley found a way to get her outer space fix using satellite data to map cheatgrass distribution. “We didn’t see any trends in vegetation change, but we did see this really weird signal on parts of the West that greened up really strongly. They basically looked like a bunch of little golf courses in 1998,” she recalled, noting that a year earlier they looked like the rest of the desert.
The El Niño of 1998, she realized, brought a change in precipitation to the region. Year-to-year variations in precipitation favor cheatgrass. “Most of the desert-adapted species can’t do anything with all of the extra water,” she explained. “But cheatgrass can.”
In the long run, however, cheatgrass thirsts for only one thing. “It’s really the fire cycle that triggers the biggest impacts on native species, native plant diversity, and native animal diversity,” she said. Cheatgrass fires create ecosystems that are “monotypic, or single species as far as the eye can see.”
The warming and drying climate of much of the West, Bethany said, is likely to increase the speed and spread of cheatgrass. Changing temperature and precipitation patterns are spreading the weed into once-unsuitable habitats in northern Idaho, Montana, and Wyoming.
By overlaying NASA satellite measurements of burnt areas across the United States with year-to-year changes in vegetation coverage, Bethany and her collaborators confirmed that cheatgrass is driving more frequent, faster-spreading, and longer-last
ing fires in shrub-dominated landscapes. “The numbers showed it’s basically burning twice as frequently as you would expect relative to its land area,” she said. “One of the things that really surprised me a lot was the influence of cheatgrass on ignition of these fires.”
Free-flying truck chains and sparks from power equipment ignite blazes more easily in cheatgrass than in other grasses. In addition, human interaction with infested land is increasing. “The fires aren’t just burning all this land that nobody cares about,” said Bradley. “They’re actually burning the land that we live on.”
Cheatgrass flourishes in disturbed terrain, and the epic floods and fires that plagued Colorado in 2012 and 2013 left the state primed for an epic invasion.
MARLYS SWAN LIVED 12 MILES NORTH of Last Chance’s downtown but worked as a massage therapist in Brush, Colorado. She wasn’t worried when she saw the cloud of smoke on the plains moving toward her house on the same day that I saw smoke rise in the high country of Rocky Mountain National Park. Grass fires are common in the flatlands, and local fire crews keep most of them from going very far. But by the time Marlys got to her brother and sister-in-law’s house, near her own, they had received two reverse 911 calls. She raced home, grabbed her two dogs, and headed to the next town to the north. Five minutes after she got there, it also was evacuated. The fire was moving almost as fast as the evacuees. As she continued driving away from the smoke, her phone rang. “My brother . . . said, ‘Your house is on fire,’ ” she recalled.
When she returned the next morning, only the chimney was standing. The rest—family photo albums, her beloved collection of books, her mother’s wedding ring—were in a pile of ash and cinders that filled the basement.
Justin Wagers, in nearby Woodrow, Colorado, manages his family’s grain fields to keep out cheatgrass. But in his second job, as a volunteer firefighter, there’s no escaping it. He was in the middle of the wheat harvest when the Last Chance Fire broke out. He and his brother Jonathan were racing to it in their fire truck when they were suddenly blinded.
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