Thinning treatments reduce the risk of wildfire and provide ecological benefits to California’s forests, but they also produce wood residues, which are frequently burned or allowed to decay, releasing carbon dioxide into the atmosphere. A new study shows how incentivizing industries that convert wood residues into useful products, such as biofuels and high-quality engineered lumber, could fund forest thinning treatments while preventing carbon emissions.
Clearing dense overgrowth from California’s forests is a critical first step toward reducing catastrophic wildfires in the state. However, whether through prescribed burning or thinning, forest restoration comes at a high cost: not only are these treatments expensive but cutting down or burning vegetation can release stored carbon dioxide, hastening the effects of climate change.
A new study by the University of California, Berkeley researchers provides a road map for how the state can effectively reduce wildfire risk through forest thinning while continuing to limit carbon emissions.
The state can both create an economic incentive for effective forest management and prevent the carbon stored in this vegetation from entering the atmosphere by creating a market for small-diameter trees and other woody biomass, particularly by encouraging the use of long-lived “innovative wood products,” such as oriented strand board.
“It’s difficult to manage our forests without releasing carbon,” said study first author Bodie Cabiyo, a Ph.D. candidate in the Energy and Resources Group at UC Berkeley. “However, if we are extremely efficient and cautious about how we use wood, and invest in innovative wood products that can use waste wood, we can achieve both net carbon benefits and wildfire mitigation benefits in California.”
Former California Gov. Jerry Brown pledged in 2018 that the state would achieve full carbon neutrality by 2045, a goal that will necessitate both reductions in emissions and investments in carbon sinks, such as forests, that can remove existing carbon from the atmosphere. Two years later, California and the US Forest Service agreed to manage a total of 1 million acres of state forest land annually through thinning, prescribed burning, and industrial harvesting – treatments that could return some of that carbon to the atmosphere.
Creating a market for forest biomass produced by forest thinning might reduce wildfire risk, avoid smoke pollution, potentially displace fossil fuels, and boost water availability. We must deal with this small diameter biomass, and there is a solution if we can only connect the dots politically and economically.
Brandon Collins
“Many people are pointing to forests as a source of sucking carbon out of the air while not adding carbon to the atmosphere,” Cabiyo said. “And, while managing a million acres per year is a fantastic and absolutely necessary goal, the reality is that managing a million acres per year will cost a lot of money, and it’s still unclear where that money will come from.”
While data on how much of the state’s forests are currently managed is limited, the researchers estimate that it is far less than the 1 million acre-a-year target. Their research shows that, with the right set of policies and incentives, the use of innovative wood products could provide both the state and private landowners with the funding they need to expand forest thinning treatments while still limiting carbon emissions.
“California has been at the forefront of both climate change mitigation and adaptation,” study senior author Daniel Sanchez, an assistant cooperative extension specialist in the Department of Environmental Science, Policy, and Management at UC Berkeley, said. “We hope our study contributes to the alignment of these two goals by demonstrating how the state can meet both its emissions reduction goals and reduce wildfire hazard, while also providing a framework for managing temperate forests around the world while attempting to meet the needs of a changing climate.”
Burn piles the size of school buses
Forest managers typically focus on removing smaller trees and underbrush while leaving many of the larger and more fire-resistant trees in place to create forests that are more resilient to severe wildfire. While larger trees can be harvested and sold as timber to sawmills, the smaller wood residues produced by forest thinning have little market value in California and are frequently burned or left to decay.
“If you drive through these forest treatment projects, you’ll see massive burn piles that can be over 20 feet tall – the size of multiple school buses – just sitting there waiting to be combusted,” Cabiyo explained. “That is a lot of carbon that will be released back into the atmosphere.”
Small trees and woody residues, on the other hand, are not useless. Engineered lumber is produced in other parts of the world, including the southeastern United States, by combining wood residues with adhesives and compressing them into large sheets. According to Sanchez, this engineered lumber is strong enough for construction, and many houses in California are already built with imported engineered wood.
Woody residues can also be converted into electricity or liquid fuels in biofuel plants, and if these plants are outfitted with carbon capture technology, this energy can be produced while removing carbon dioxide from the atmosphere.
“Some people focus solely on what’s in the forest when it comes to carbon storage or sequestration,” Sanchez explained. “We wanted to assess the carbon emissions associated with these new products’ entire life cycle.”
The study predicted future carbon emissions under two scenarios: business as usual, assuming little forest management, and a scenario in which the state has established a market for wood wastes. To make the comparison, the researchers performed a cradle-to-grave analysis, examining the carbon emissions connected with each step of a product’s life, from the time the wood is harvested until the product’s end of life.
The state might develop a market for wood leftovers that does not generate significant carbon emissions by investing in local firms that create novel wood products or convert biomass into biofuels using carbon capture technology, according to the report. The paper also provides a model scenario in which the state incentivizes the use of engineered wood in multi-unit affordable housing construction.
“If California begins to use thinning treatments on a wide scale, we’ll be creating a lot more lumber and wood wastes, and where that material goes is a question,” Cabiyo said. “We discovered that employing that new material to build cheap housing might provide substantial carbon advantages, owing to the fact that those buildings would otherwise be built with steel and cement, both of which have significant carbon emissions.”
Thinning treatments also minimize the likelihood of major wildfires, which can burn millions of acres of vegetation at once and kill even giant trees, assisting California’s forests in maintaining their long-term potential to store carbon. According to study co-author Brandon Collins, a research scientist with Berkeley Forests and the US Forest Service, these treatments have also been found to give several ecological benefits, such as increased water availability and habitat diversity.
“Creating a market for forest biomass produced by forest thinning might reduce wildfire risk, avoid smoke pollution, potentially displace fossil fuels, and boost water availability,” Collins explained. “We must deal with this small diameter biomass, and there is a solution if we can only connect the dots politically and economically.”
