DENVER — In 2020, historic fires raged across Colorado, and while firefighters and Mother Nature extinguished the flames, Coloradans are now dealing with the aftermath as rain sparks mudslides, flash floods, and deadly destruction in burn scar areas.
Three adults are still missing after Tuesday mudslide and flash flooding in Poudre Canyon. The sheriff’s office’s Damage Assessment Team found that six residential structures on Black Hollow Road were destroyed in the mudslide as well as a detached garage. One other residential structure was damaged.
Last year, wildfires burned through trees, shrubs and vegetation — essential resources that help absorb water and hold back mudslides. A potential consequence of the wildfires is also soil erosion, which can make soil repel water.
“When there is extreme or severe burning, particularly of the soil, you get hydrophobic soils that don’t allow water to actually penetrate into the soil and instead it just moves over the top of that soil,” said Marin Chambers, a forest ecologist with Colorado State University.
She adds that it’s hard to predict how long it will take the soil to recover, but depending on the severity of the fire it could take one or a few years.
“Usually within about a year or two that hydrophobicity starts to break up a little bit,” said Chambers.
The U.S. Forest Service can also help speed up the recovery process by aerial mulching and aerial seeding.
Historically, wildfires in Colorado have led to significant flooding events one to five years later, according to Chambers.
While mudslides pose a threat to homes and drivers in populated areas, they also help spread nutrients when they enter creeks, rivers, and streams.
“Forests and fires go hand in hand. Forests depend on fire for an enormous amount of ecological processes, so that’s things like nutrient, cycling, killing smaller trees, creating situations where the older trees can become more fire resilient,” she said.
Fires can help restore unhealthy forests, but it’s unclear what the recovery process will look like in Colorado forests, which are home to highly-adaptable lodgepole pines, that were plagued by the mountain pine beetle epidemic. Lodgepole pines release seeds following a fire, but if the trees were killed by beetles it’s unknown if the seeds will be viable.
Chambers says forest experts will face a challenge as they factor in climate change and work to determine if they must step in to help plant trees and vegetation or simply let mother nature regenerate the ecosystem.
“How do we plant? And what do we plant more particularly to be resilient into the future for future disturbances like pine beetle specifics, spruce beetle epidemics, and also fire and other kinds of large mortality events?” said Chambers.