Forests managed by private timber companies may be significantly more vulnerable to wildfire than those overseen by public land agencies, according to a new study published in Global Change Biology. Researchers found that the likelihood of severe fire was 1.5 times higher in privately managed forests across California’s northern Sierra Nevada.
Led by Jacob Levine from the University of Utah, the study attributes this elevated risk to differences in forest structure. Dense, uniformly spaced trees with continuous vegetation from the forest floor to the canopy create ideal conditions for megafires: “You can think about stacking a bunch of matches together in a grid — that’s going to burn a lot better than if you have those matches dispersed as smaller clumps,” he said.
To assess forest conditions, Levine used airborne LiDAR (Light Detection and Ranging) data collected in 2018 through a collaborative effort involving the U.S. Forest Service, U.S. Geological Survey, and NASA. This advanced technology emits billions of laser pulses that reflect off vegetation and terrain, allowing researchers to generate high-resolution maps of forest composition.
The timing of the LiDAR survey proved pivotal.
The dataset was gathered just one year before five major wildfires swept through the region between 2019 and 2021—including the Dixie Fire, the largest wildfire in California’s recorded history. “We have a really detailed picture of what the forest looked like immediately before these massive fires,” he said. The study focused on Plumas National Forest, which Levine described as “a mosaic of private industrial and public ownership.” The region’s mixed conifer ecosystems are naturally adapted to periodic low- and medium-intensity fires that clear underbrush and leave behind patchy tree clusters. However, decades of fire suppression and industrial logging have disrupted these natural cycles, increasing fuel loads and the potential for more intense blazes.
Levine’s team analysed burn severity across 1.1 million acres affected by the five fires. Although all ignitions occurred on public land, the most severe damage was concentrated in privately owned areas. According to the study, 81.6% of the surveyed land was publicly managed, private industrial timber companies owned 11.7%, and 6.6% by non-industrial private entities. Forests under industrial ownership were associated with a 1.45-times increase in the odds of high-severity fire compared to public lands, and a 2.1-times increase relative to non-industrial private zones.
The researchers also identified elevated fire risks in areas adjacent to industrial timber holdings, raising concerns for nearby wilderness areas, small landowners, and urban communities. “A bigger fire can easily reach the canopy in dense forests,” Levine said. “Then it’s ripping through one tree after another, tossing out chunks of burning material miles in advance.”
And unlike the uniform, grid-like plantations typical of industrial timber operations, public lands tend to support a broader range of uses—including recreation, grazing, ecological restoration, and wildlife corridors. These lands are also subject to public oversight and environmental litigation, which can restrict tree removal and influence forest management practices.
The authors hope their findings will inform future policy decisions and guide more effective wildfire mitigation strategies. “Thanks to our access to forest data from before and after the blazes,” Levine said, “we were able to understand the types of forest structures that lead to high-severity blazes.” That insight, he added, could help stakeholders “target mitigation strategies to get ahead of this massive fire problem while still producing enough timber to meet market demand.”
For more information: Levine, J. I., B. M. Collins, M. Coppoletta, and S. L. Stephens. 2025. “ Extreme Weather Magnifies the Effects of Forest Structure on Wildfire, Driving Increased Severity in Industrial Forests.” Global Change Biology 31, no. 8: e70400. https://doi.org/10.1111/gcb.70400.
