The Marshall Fire exposed the need to reduce wildfire risk on the grasslands of Boulder County. But there’s a problem: Even the best fire-prevention techniques on the plains don’t work as well as they do in the mountains.
“Grasslands are much different than forests,” said Katharine Suding, a professor of ecology and evolutionary biology at the University of Colorado Boulder, who is advising a Boulder County grasslands working group established to help prevent another Marshall Fire.
On the plains, Suding said, a fire can burn all plants in its path only to have intact roots grow back stalks within months. Trees take longer to return. If a fire thins a forest — through a wildfire or a prescribed burn — that forest enjoys at least a few years of reduced risk. Grasslands don’t.
“We might get a year of protection after a prescribed fire” on the plains, said Stefan Reinold, a resource manager for county Parks and Open Space. Reinold is also a member of the grasslands working group, along with scientists, land managers, ditch company mangers and fire protection district members. The group is a subset of the Boulder County Fireshed that is made up of a similar cohort of local scientists and land managers working to reduce fire risk.
A former forester for the county, Reinold said prescribed burns are difficult to implement in the mountains — and even harder on the plains. Much of the county’s open space on the plains is leased agricultural land. Farmers who might be open to their grasslands being scorched intermittently probably don’t want them burned every year, which is what it would take to be effective.
Still, the public, especially those recovering in the Marshall Fire burn scar of Superior and Louisville, want something done.
“There’s a lot of pressure, of course, to come up with solutions,” Reinold said, and he is sympathetic. “But one of our biggest concerns is there is no clear solution with grasslands. If there were, we would be all about it. We’d be out there trying to decrease fire hazard in every aspect we could.”
Reinold said since the Marshall Fire, the county has been criticized by residents for mismanaging its grasslands. One of the suggestions residents often make is increased grazing. But much of the area burned by the Marshall Fire had been grazed — multiple times — in the year leading up to the fire.
“We grazed three times,” Reinold said. “Which is getting to the level of overgrazing in some areas that abut Louisville.”
Mowing is another recommendation he often hears. Though it cuts some fire fuel, mowing leaves vegetation on the ground where it can still carry fire. And the amount of mowing required is untenable. Reinold said Boulder County has 343 miles of agricultural property lines. Should Parks and Open Space put a 100-foot buffer along property lines to protect vulnerable neighborhoods, it would equal almost 4,000 acres they’d have to mow — “and often” — because the grass keeps growing.
Reinold raised the possibility of planting low-growing vegetation where prairie and neighborhoods meet, the idea being such vegetation wouldn’t burn with the ferocity of dried-out grass.
“There’s no data saying that would work,” Reinold said. “But we could try.”
But weather conditions that fueled the Marshall Fire might have overcome even perfect grasslands management. Eighty mile-per-hour winds came after a fall that saw almost no moisture.
“Anytime a fire has gotten established with winds less than 30 miles per hour, we’ve gotten control of it,” Reinold said. “But nothing has proven able to stop a fire backed by 80 mile-per-hour winds.”
Suding agreed, saying the risk of catastrophic fires will increase as fall in Boulder gets drier with worsening climate change. “There are actually many grassland fires each year in this area,” she said. “But most occur when the plants are green and weather conditions are not super windy, so they get put out before they get big.
“In wind events like what occurred during the Marshall Fire, it would be hard to imagine that any active management of grasslands could reduce the risk.”
‘No silver bullet:’ Home-hardening, targeted grazing, prescribed burns
Suding said a better bet might be investing in active patrols to spot ignitions on high-risk days and safeguarding homes.
Such safeguarding, also known as home-hardening, is the specialty of the Wildfire Partners Program that has mainly worked with homeowners to reduce their fire risk in unincorporated western Boulder County. Using money from the 1A sales tax that passed last year, Wildfire Partners is expanding into eastern Boulder County, helping residents understand the fire risks certain choices might pose to their homes — like wooden fences, shrubbery up against siding, and vegetation prone to violent incineration, like junipers. Reinold said home-hardening, coupled with experimental techniques like targeted grazing is our best bet at avoiding another Marshall Fire. Targeted grazing puts cows on high-risk areas, like borders of prairie and neighborhoods, to munch down fuel before the fall shoulder fire season.
Suding added that creating better models for grassland fire risk — an historically underrepresented research area when compared to forest wildfires — should be a top priority.
“We need to know more before making quick decisions,” she said, explaining that hasty actions to reduce fire risk might not only fail to do so, but could also harm the landscape. “If we only think about reducing grassland fuels and do it by mowing or other treatments, that might really damage soil health and biodiversity. We don’t want that, particularly since grasses regrow within a few weeks after a treatment.” That’s one of the goals of the working group.
In early June, members said they hope to put out a document to show residents what is already being done to address fire risk on grasslands, and what practices should be adopted moving forward.
The main takeaways of their work will likely be a combination approach: some grazing, some prescribed burns, and some investment from the public in protecting their properties as best they can.
“There’s no silver bullet,” Reinold said. “If there was clear information of what to do, people would have done it already.”