Does logging really reduce wildfire danger? New California study finds key exception

San Francisco Chronicle​

13 hours ago

The timber industry and its supporters, joined by many in the Trump administration, have long promoted logging as a way to reduce fire danger. Some even blame declining timber operations in recent decades for the uptick in catastrophic wildfire.
A growing body of research, however, suggests the benefits of logging are far more limited.
The latest study to examine the impact of harvesting trees on fire behavior, published Wednesday in the journal Global Change Biology, finds that lands administered by private timber companies were nearly 1½ times more likely to burn at 'high severity' levels than public lands with less timber production.
The reason, say the authors, is that commercial logging sites tend to have trees that are tightly packed, evenly spaced out and structured with 'laddered' rows of branches — all of which is ideal for starting and spreading flames.
'It's pretty intuitive in a way,' said Jacob Levine, post-doctoral researcher at the University of Utah's Wilkes Center for Climate Science and Policy and lead author of the new study. 'If you have a continuous fuel bed, it's going to vector fire across the landscape.'
The authors, from the University of Utah, UC Berkeley and the U.S. Forest Service, drew their conclusions by analyzing burned areas in Northern California, where wildfires have been particularly destructive in recent years.
Their findings build on previous studies that dispute the notion that removing trees invariably reduces 'fuels' and diminishes fire risk. The authors, though, say that tree removal itself is not causing the hazard, just the way it's done. Their paper points to a role for logging in reducing forest density and thereby improving fire resiliency.
According to the authors, selectively removing mostly small trees, clearing strips of forest to provide what is known as shaded fuel breaks, and thinning the understory can lower the intensity of a wildfire. Studies have shown various levels of success with these practices. The general consensus is that prescribed fire, because it mimics natural fire and organically purges overgrown vegetation, is the most effective tool for limiting high severity burns and should be added to any mix of forestry work.
Such targeted approaches, however, don't generate as much wood production as plantation-style harvesting, in which large trees are generally clear cut before replanting compactly to maximize yields.
The mounting research has implications for forest policy, though success is often in the nuance of the execution.
The Trump administration recently identified a goal of increasing timber production on federal forests by 25%. It is hoping to do this largely by rolling back environmental reviews and expediting permitting of logging projects. Part of the impetus, as stated in a presidential order, is 'wildfire risk reduction' and to 'save American lives.'
Scott Stephens, a professor of fire ecology and forestry at UC Berkeley and a co-author of the new study, said setting numerical objectives for the amount of timber you want, instead of what is suited to forest conditions, is generally not the way to ward off damaging fires. Simply cutting down the biggest trees, which are generally the most fire-resistant, won't increase resiliency, for example.
'You need to put fire mitigation upfront,' Stephens said. 'Maybe you're going to do a commercial harvest, maybe do some thinning, put in some shaded fuel breaks. But
if you're only going to go in there and give every forest a (harvest) target, that doesn't work.'
The need to limit high-severity fire, which is characterized by killing large numbers of trees, is becoming increasingly evident. Such burns are harder to put out, cause sometimes irrevocable damage to forests, wildlife and nearby communities and result in landscapes that sequester less planet-warming carbon. In some cases, a whole new, tree-less ecosystem of shrubs and grasses emerges.
The logging industry has cautioned against making broad claims about how their work affects fire risk.
George 'YG' Gentry, senior vice president of regulatory affairs for the California Forestry Association, had not seen the latest study but said it's hard for any single paper to capture all the factors that affect fire, from weather to elevation to terrain.
'Any one study that points to this or that, I'm kind of skeptical,' he said. 'If you're doing appropriate thinning, if you're doing appropriate fuel management, you can really mitigate fire behavior.'
The new paper used the Plumas National Forest in the northern Sierra Nevada as the study site. The area was hit hard by five major wildfires between 2019 and 2021, including the 963,000-acre Dixie Fire, the second largest in state history.
It so happens that the Plumas National Forest and surrounding property, including private timber parcels, had been surveyed by overflights using airborne light detection and ranging, or LiDAR, in 2018 — providing a baseline of forest conditions before the fires.
By analyzing the changes, the researchers determined that private timberlands were 1.45 times more likely to experience high-severity fire than the federal holdings, which consisted largely of areas that had been leased for logging, though with more restrictions than the company-owned sites.
The study points out that the federal lands also often saw high-severity fire and were not a model for sound forest management. It was just that the private forests were less fire resilient because of their denser, more uniform make-up.
Identifying what was making the fires worse, the authors say, enables improvements to be made on both private and public lands. Certain forestry practices that aim to decrease density, according to the study, will help temper the severity of even the most extreme fires, which bodes well for the future as wildfires become increasingly intense.
'We're not just fighting this losing battle automatically because of climate change,' Levine said. 'As fire weather gets worse and worse with climate change, we can still implement management that reduces severity.'
Several studies over the past decade, and even earlier, have found that wildfires have often burned more intensely in areas where logging has occurred.
Some research, including a 2016 paper that analyzed 1,500 fires and found that burning was worse in places with more cut trees, suggests completely rethinking logging as a fire-mitigation tool. The wind and heat from the sun that gets into an exposed logging site, some say, regularly exacerbates fires. Other research has underscored the need to reduce tree density, after decades of fire suppression, but only with selective logging practices.
The authors of the new study say the timber industry and all consumers of wood products stand to benefit when forests are better protected from massive blazes.
'Logging is an important industry,' Levine said. 'I don't want to vilify timber companies, by any means, but I'm not sure the raw focus on timber production is the way we want to go about reducing fire severity.'