Why Grassland Fires Still Surprise Us

In 2017, the first in-depth study of wildfires on the Great Plains revealed something striking: Since the 1980s, the number of acres burned each year on the nation’s largest expanse of prairie had increased by 400 percent. The greatest surge occurred on the Great Plains’ western boundaries, which, in part, covers nearly half of Colorado. In a news release, ecologist and co-author Dirac Twidwell predicted that the Great Plains would be the next “wildfire frontier.”

Despite these findings, fires in forests, not grasslands, seem to make up the core of popular understanding about Colorado wildfires—so much so that, when the Marshall Fire swept through Boulder County on December 30, forcing a mass evacuation and destroying more than 1,000 homes, many were shocked that a winter wildfire could level entire suburban subdivisions. (In a December 31 press conference, Senator Michael Bennett described the flames as “very unusual,” and United States Representative Joe Neguese called them “unprecedented.”) 

But while the extent of the devastation was unprecedented—it was the most destructive fire in Colorado history in terms of property damage—many people familiar with fire patterns, like incident commander for the Rocky Mountain Type 1 Incident Management Team (a group that handles natural disasters too big for local organizations to battle alone) Dan Dallas, were not surprised to see flames surging through grasslands and into an urban area. “Homes/buildings are just another form of fuel to a fire,” he told 5280 via email.

The fact is, forests aren’t the only flammable landscapes. In an analysis of area burned by wildfires in the 11 Western states between 1984 and 2020, John Abatzoglou, who runs the University of California Merced’s Climatology Lab, found that only 35 percent of those infernos have been in forests. Local fire departments also spend more time on grass and brush fires than blazes in forests, according to data from the National Fire Protection Association (NFPA), a nonprofit focused on eliminating deaths, injuries, and economic losses due to wildfire. They’re responding to forest fires just seven percent of the time, compared to 39 percent for grass fires.

Despite those numbers, Abatzoglou says many ignore the dangers of living near open grasslands. “The general public tends to think that they aren’t in a fire-prone environment if they don’t see the forest right up against the neighborhood,” he says, which is a dangerous assumption because, as the Marshall Fire illustrated, grassland fires can move incredibly quickly. “By thinking that way,” Abatzoglou says, “we may be increasing the vulnerability of communities that are not in forested environments but are still quite fire-prone.”

That vulnerability emerges in several ways. Firewise USA, an NFPA program that helps communities prepare for future wildfires (in part by educating them about how to make sure their homes are less susceptible to flames), works with 186 sites across 26 Colorado counties, says Michele Steinberg, NFPA’s Wildfire Division Director. Most Colorado participants are located near forests, with a striking lack of engagement in the Eastern Plains.

Steinberg is quick to point out that Eastern Plains residents, who typically don’t live in neighborhoods as dense as the ones Firewise USA usually serves, may be using other mitigation strategies. But both Louisville and Superior, the two Boulder County suburbs hit hardest by the Marshall Fire, weren’t participants, even though scientists knew the towns are located in the wildland-urban interface (WUI), the area where wilderness and human-developed land mingle, and where people are most likely to be impacted by wildfire.

Many of Boulder County’s celebrated wildfire mitigation strategies, like the Wildfire Partners program that works one-on-one with homeowners to make their homes as fire-safe as possible, focus similarly on the mountains and the foothills, not communities in grasslands. “Mitigation programs need to grow in terms of our capacity and budget, but we also need public support and political leadership,” says James Webster, Wildfire Partners’ program coordinator. “It’s hard to convince people who don’t know they’re in danger to do mitigation.”

Michelle Kelley, a spokesperson for Mountain View Fire Rescue (MVFR), a fire department serving parts of Boulder County (including Superior), says the fire preparedness levels in foothills communities simply look different than in suburban communities like Superior. She believes it can be hard for individuals to receive that education when they feel safe and busy with other worries in their life. “I listen to what’s going on out there because it’s my job,” Kelley says. “However, not everyone does, and you can’t fault them for that. We just keep putting the information out and trying to find ways to help people hear it and do something about it.” Her agency attends National Night Out events and hosts open houses at the fire station to teach residents how to protect their homes from wildfires, and uses social media to spread the word, too. 

Building codes represent another liability. Most towns in Colorado use the 2018 International Residential Code, a set of rules to guide the construction of new homes that can be combined with other International Codes, depending upon the area’s requirements. One of those “I-Codes” is the International Wildland-Urban Interface code, which provides guidance to ensure homes in the WUI are built to be more resistant to blazes. The City of Boulder uses the WUI code. Louisville and Superior, however, do not. The former’s city leaders did discuss incorporating the WUI Code during its most recent City Council meeting on February 1.

Louisville and Superior are far from alone in needing to revamp building codes. Jennifer Balch, who directs University of Colorado Boulder’s environmental research facility Earth Lab, says many homes in the WUI have not been built with that risk in mind. “We’ve got a lot of homes between Colorado Springs up to Fort Collins that are built with wood, wood siding or asphalt roofing, wood decks, and wood fences,” she says. “All that is flammable.”

None of the experts interviewed for this story blame the people of Louisville, Superior, and other areas scorched by the Marshall Fire for the devastation they’ve endured. “If you’re living in an ecosystem where fire tends to be more frequent,” NFPA’s Steinberg says, “you’re more likely to have a heightened awareness of the risks.” And in Colorado, most of the recent high-profile wildfires, like the Cameron Peak and East Troublesome fires, have occurred in mostly forested areas. Those infernos represent a trend, not an anomaly. “We’ve seen a doubling of forests [in the U.S.] that have burned since the 1980s,” Balch says.

The varying behaviors of different types of wildfires may explain some of our collective bias, too, says Matt Cahill, program director for Sagebrush Sea (an effort to protect and restore sagebrush steppe focused on Oregon, Idaho, Nevada, Utah, Montana and Wyoming, though Colorado’s northwest corner hosts this ecosystem, too). Forest fires last longer than brush or grass fires because the woody fuel takes longer to burn. The high heat can often cause more destruction, too. “They often imprint on our memories differently,” Cahill says. “We can remember what forest fires look like through the imagery of crowds of trees bursting into flames.”

Forest fires also emit more smoke than grasses, so they have a better likelihood of catching the eye of a layperson. They also typically leave a deep scar on the land. Grassland fires, on the other hand, tend to grow back quickly because so much of their energy is stored underground in their roots, Balch says. 

Still, massive, destructive grass and shrubland fires do occur—often. Just a few weeks prior to the disaster in Boulder County, high winds and unseasonably warm, dry weather sparked a swiftly moving grassland fire in Denton, Montana, that damaged about two dozen homes. Similar to the Marshall Fire, the lack of winter snowfall is thought to have played a role in that prairie conflagration, which was just one of three that occurred in the area this year.

Many of the largest grassland fires haven’t impacted residential areas, though, because homes in grass and shrublands are often not located close together. Balch points to the Martin Fire in northern Nevada, which grew to nearly 450,000 acres in July 2018. The grassland blaze destroyed six ranches and extensive grazing land and habitat (a huge economic loss), but it didn’t receive extensive national coverage. “No one talked about that fire,” Balch says, “because it was in the middle of nowhere. Nobody died because it wasn’t next to anybody’s home or neighborhood.”

But many Coloradans do live in neighborhoods next to vulnerable open spaces. Residential areas like Parker and Castle Rock may not be nestled amidst the trees, but they’re still in the WUI. Victoria Donovan, the lead author on the major study about wildfires on the Great Plains, says that both Louisville and Superior fell within the range she and her co-authors examined in their 2017 paper. “The High Plains experienced some of the greatest increases in large wildfire number and total hectares burned by large wildfires in the Great Plains over the duration of our study,” she told 5280 via email.

So where do we go from here? The puzzle is a complex one, but for Steinberg, one piece involves improved communication. “The threat to people and homes is a set of conditions, not an area on the map,” she says. There needs to be an ignition source, oxygen, and fuel, and it doesn’t matter if that fuel is trees, shrubs, or grass. That recipe culminated in a brutal fire on December 30 in Boulder County. “Could we be doing a better job of communicating where people have a risk from wildfire of any source?” Steinberg asks. “Yes, absolutely.”

Sagebrush Sea’s Cahill highlights the importance of nuanced communication, too.“Fire is part of almost every single landscape in one way or another,” he says, even though fire behavior and frequency varies across forest, sagebrush, and grassland ecosystems. He’s hopeful that agencies like the Bureau of Land Management and the U.S. Forest Service, as well as state and local leaders, are recognizing that all ecosystems need to be managed to try and return them to their natural relationship with fire.

“All of these systems are out of whack, and we’re doing the best we can to manage them into normalcy,” Cahill says. “But until then, it’s hard for us to know what the new fire normal will be. We shouldn’t be surprised that we’re getting surprised.”

(Read More: The Unpredictable Behavior of the Ptarmigan Fire Near Silverthorne Is the New Normal)