After more than a century of fire suppression in California forests, new research from the University of California, Berkeley indicates that prescribed burning can have long-term benefits for forest carbon storage and productivity. While controlled burns release carbon dioxide into the atmosphere in the short term, the study found that repeated use of prescribed fire helps maintain large, fire-resistant trees and eventually increases overall forest productivity.
“Over time, we found that the productivity of unmanaged tree stands decreased, likely due to increased competition and climate stress. Meanwhile, prescribed burning helped maintain large, fire-resistant trees, eventually increasing the productivity of these stands,” said study lead author Yihong Zhu, a graduate student at UC Berkeley. “We wouldn’t be able to detect such a benefit had we not been able to monitor these stands over 20 years and three entries with controlled fire.”
The research was conducted at Berkeley’s Blodgett Forest Research Station in the Sierra Nevada. Since 2000, researchers have applied various management techniques—including prescribed burning and restoration thinning—to different plots while leaving others untouched as controls. The study tracked how each treatment affected carbon storage and net productivity over two decades.
According to John Battles, professor of forest ecology at UC Berkeley and senior author on the paper: “Nature-based climate solutions were a big focus of the 2024 Paris Climate agreement, and either maintaining or increasing forest carbon is one of the most cost-effective strategies. We found that, with some management, you may lower the total carbon storage of a forest, but you make it safer from loss from wildfires or pathogen outbreaks. We call it stable carbon.”
The findings suggest trade-offs between immediate carbon emissions from controlled burns and longer-term gains in ecosystem resilience and stable carbon storage. By tracking all pools of carbon—from decaying needles to tree trunks—researchers observed that while control plots stored more total carbon initially, regularly burned plots saw significant increases in net productivity after multiple treatments.
“After the first burn, the net productivity of those plots was really low and the controls looked a lot better,” said John Battles. “But by the third burn, the patterns had switched.”
Prescribed burns also help reverse trends caused by past fire suppression policies. In areas where small shade-tolerant trees have proliferated—creating conditions for severe wildfires—controlled fires reduce undergrowth and promote larger species like ponderosa pine.
“We’ve always wondered if we could restore these ecosystems to a more functional state—lower density and more frequent fire—do we eventually see a bonus? Do we get that golden nugget? And in this work, we were able to actually measure it,” said study co-author Scott Stephens.
Previous research by this team showed that combining prescribed burning with mechanical thinning is most effective for reducing wildfire risk but comes with higher initial carbon costs. The current findings offer guidance for communities choosing between management options based on local priorities such as wildfire prevention or maximizing stored forest carbon.
“We’ve got to get these treatments out there,” Battles said. “Some treatments might be better than others in certain situations, but now we’ve made the trade-offs explicit so we can pick the right approach.”
Other contributors include Daniel Foster, Brandon Collins, Robert York, Ariel Roughton and John Sanders from UC Berkeley; Emily Moghaddas from U.S. Department of Agriculture Forest Service.
