Fighting Fire With (Prescribed) Fire

We write a lot in Erosion Control about the effects of wildfires on soil and about how to prevent erosion after a fire removes vegetation. It’s the cover story of our June issue, in fact. An article from our November/December 2015 issue discusses how the policy—common in the US since the early 1900s—of extinguishing every forest fire as quickly as possible led to the buildup of excess fuel, leading to larger and more destructive wildfires over time.

A recent study by the US Geological Survey and the National Park Service focuses on fire in a slightly different way. The study recommends using prescribed fires to thin forests in drought-stricken areas like California and other parts of the country. When some of the trees are removed by burning, the lead author of the study explains, the trees that remain have more water available to them and are better able to survive drought conditions. One result—besides a healthier forest—might be a reduction in unintended wildfires.

The researchers looked at both burned and unburned forests in Kings Canyon, Sequoia, and Yosemite national parks, all of which are experiencing drought. Tree species included ponderosa pine, white fir, and Douglas fir. Although the forests at higher elevations didn’t appear to be losing many trees to the drought, those at lower elevations did. And in forests that had not had fires before the beginning of the drought in 2012, tree mortality was higher.

“Understanding the relationship between drought, fire, and tree mortality from fires adds some important wrinkles to how we manage forests,” said Tony Caprio, a fire ecologist with Sequoia and Kings Canyon National Parks and study co-author. “One of our goals is to reduce risks of undesirable wildfire using prescribed fire. Maybe prescribed fire can also help prepare these forests for a drier future.”

The study was published in the journal Fire Ecology and is available here.