• Posted November 14, 2023

Controlled Fires Cut Wildfire Risk by 60%, Study Shows

Controlled forest burns can prevent the sort of high-intensity wildfires that have plagued the Western U.S. and Canada as a result of climate change, a new study argues.

A low-intensity fire in the mixed conifer forests of California provides an estimated 60% reduction in the risk of a catastrophic wildfire, and that effect lasts at least six years, researchers report in the journal Science Advances.

Controlled burns also could provide a smaller but still significant reduction in risk in oak-dominated forests, researchers added.

"I'm hopeful that policymakers will rely on this work as motivation and support for the scale-up of beneficial fire as a key strategy in preventing wildfire catastrophes,"co-author Michael Wara, director of the Climate and Energy Policy Program at the Stanford Woods Institute for the Environment, said in a Stanford news release.

"Beneficial fire is not without its own risks -- but what our study shows is just how large and long-lasting the benefits are of this crucial risk reduction strategy,"Wara said.

The U.S. Forest Service has proposed treating about 50 million acres of forest through a mixture of "fuel treatment strategies," which can include burns as well as thinning, pruning and logging to reduce the amount of combustible vegetation, researchers noted.

For the study, researchers reviewed two decades of satellite monitoring of wildfires covering nearly 25 million acres of California forests, looking at fire intensity and fire severity.

Previous studies have shown that prescribed fires and unplanned low-intensity wildfires also can reduce the risk of a larger blaze.

These smaller fires clear away vegetation and smaller trees, helping forests achieve a more fire-resilient mix of trees and preventing fires from growing too intense, while still leaving the high tree canopies intact, researchers said.

They created a model that assembled unburned areas into a synthetic landscape that closely resembled the attributes of previously burned landscape, taking into account conditions like weather patterns, elevation and vegetation type.

This approach allowed them to estimate how much a low-intensity burn would reduce the risk of larger, more devastating wildfires.

The study comes almost exactly five years after the Camp Fire, the deadliest wildfire in California's history. Rising temperatures and a history of fire suppression have allowed tinder-dry trees and brush to build up, providing fuel for future blazes.

Previous Stanford-led research has indicated that California needs prescribed burns or vegetation thinning on nearly 20% of the state's land area -- about 5 million acres -- to create more resilient, fire-resistant forests.

"Wildfires present substantial threats to both our ecosystems and human well-being. As scientists, our constant goal is to find practical solutions,"lead researcher Xiao Wu, an assistant professor of biostatistics at Columbia University who worked on the paper as a data science fellow at Stanford, said in the news release.

More information

The U.S. Centers for Disease Control and Prevention has more about wildfires.

SOURCE: Stanford University, news release, Nov. 10, 2023