Building houses with small trees can fight California megafires: study

A state-sponsored market in wood products made from small trees — of the sort that serve as kindling for California’s destructive summer wildfires — could help store carbon, fund forest treatments and create material for affordable housing, according to a study from the University of California, Berkeley.

The study aims to bridge a gap between California’s forest and climate policies. In 2018, then-Gov. Jerry Brown (D) committed the state to reaching carbon neutrality by 2045, and in 2020 the state partnered with the U.S. Forest Service to manage a million acres of forest a year through industrial thinning and prescribed burns.

But burns are unpopular and release carbon dioxide, and the thinnings are an expensive proposition that, even when carried out, can lead to high carbon emissions.

“It’s hard to manage forests without releasing carbon,” said study co-author Bodie Cabiyo in a statement. “But if we’re really efficient and careful about how we are using the wood and invest in innovative wood products that can use waste wood, then we can achieve both net carbon benefits and wildfire mitigation benefits in California.”

But a market in alternative wood products like “oriented-strand board” — a particle board-like composite that California currently imports from the pine basket of the Southeastern U.S. — could fund pilling that product out of the forests permanently, locking the carbon down in houses and buildings, according to Cabiyo.

Tree thinning is intended to remove small, young trees that otherwise crowd around larger, more fire-resistant mature ones, serving as “ladder fuel” that allows large fires to climb into their otherwise unreachable crowns. This is backbreaking, tedious and expensive work, and in the absence of a commercial market, small trees and branches tend to be burned in piles or left to decay.

The researchers estimated that the state is still far below its target of 1 million acres per year. 

“While the goal to manage a million acres per year is fantastic and absolutely necessary, the reality is that a million acres per year will cost a lot of money to manage, and it’s still unclear where that money is going to come from,” Cabiyo said.

The Berkeley study compared the carbon emissions under a “business as usual scenario,” in which thinning efforts remain at their current, low levels, with one in which the state establishes a market for wood residues, ideally in the form of construction materials that can be permanently sequestered in buildings. 

Under the second scenario, California could manage 0.5 million acres of forest a year without an increase in either direct subsidies or carbon emissions, Cabiyo wrote on Twitter.

The impact is far greater for innovative wood products, which hold down carbon indefinitely, than it is for uses like woods-based fuels like those produced in the Southeast for export to Europe and Asia — even if those fuels are equipped with carbon capture and storage systems to retain their emissions, the report found.

There are three policies in California’s 2021-2022 state budget that impinge directly on this issue, said coauthor Daniel Sanchez. A $49 million climate catalyst fund will provide investment for biomass technologies; a $50 million grant to the Department of Conservation funds a forest biofuels demonstration project; and $3 million goes to the Governor’s office to fund planning and research into new biomass markets. 

“If California starts doing thinning treatments at a large scale, then we’re going to be producing a lot more lumber and wood residues, and where that material goes is a question,” Cabiyo said. 

“We found that using that new material for building affordable housing could produce massive carbon benefits, largely because those buildings otherwise would be built with steel and cement, which have significant carbon emissions associated with them.”

Updated at 3:30 p.m.