Sacramento’s political evolution

European colonization, these forests experienced fire once every 10 years or less, leading to open forest structures very similar to this one. Here, two years ago, Roughton, York and their colleagues conducted a prescribed burn to remove excess fuel from the ground and reduce the risk of wildfire.

“I think it’s important to remember that nature hasn’t taken its course without a lot of human intervention since the last glaciation, because there was strong Indigenous burning here,” said John Battles, a professor of forest ecology at Berkeley. “There has always been intense human stewardship of one sort or another.”

Rob York says a healthy forest is one that you can run through.

According to the researchers, it took 15 to 20 years of active management, followed by regular maintenance, to get the forest tract to this state. Over the years, they have worked to achieve the open forest structure by harvesting some of the bigger trees for timber, but leaving the largest behind. They have also used a machine called a masticator to chip up smaller trees and conducted regular prescribed burns.

While there are forest management strategies that can be effective on a shorter time scale, it usually takes at least a few separate treatments over the course of a few years to successfully restore a forest and reduce its wildfire risk, York explains.

“It can be a challenge to get to the forest structure that we want,” York says. “It takes a lot of time, and it takes a lot of investment.”

Climate change is also narrowing the annual windows of time when conditions are best for prescribed burning, limiting when and how often foresters can safely burn. Hot, dry conditions usually make prescribed burning too risky during the summer, while rain and snow in the winter can leave the forest too wet and damp for fire to burn. However, research at Blodgett is showing that, with the right management decisions, prescribed burning during the winter can be made more viable.

“Because of timber harvests that removed some of the canopy and subsequent treatments to remove the ladder fuel, we now have more light hitting the ground, and it dries out faster,” Roughton said. “We’ve gotten to the point out here where we’re able to burn more easily because of our past management actions.”

Friends of the forest

While York likes to imagine running through the trees, Battles has a slightly different metric for evaluating the health of a forest.

“You need to be able to run through the woods,” Battles said. “But I also want to see all six of my friends as I do my run.”

Battles’ friends are the six tree species that make up the Sierra mixed conifer forest: oak, ponderosa pine, sugar pine, white fir, Douglas fir and incense cedar. Fire suppression — and the dense, overgrown forest structures that can result — often favor the survival of some of these species over others, leading to forests that are dominated by just one or two species. This lack of biodiversity can make the forest, as a whole, less resilient to stressors like bark beetles or tree pathogens, which often target some of these species, but not others.

John Battles likes to see a mixture of all six tree species that make up the Sierra mixed conifer forest.

According to Battles, the open structure and frequent fire at this tract of Blodgett has allowed all six of his friends to flourish.

“I see my friend, ponderosa pine, which you don’t see as frequently in the unburned forest because it’s shade intolerant — it needs light. I see oak, and it also requires fire to get a lot of the oaks,” Battles said. “I see all six of my friends all here, and you only see them when you have management like this.”

Over the past 20 years, research has shown that prescribed burning and mechanical thinning with tools like the masticator can also benefit soil quality and water availability, while having no significantly negative impacts on forest ecosystems. While burning or otherwise removing plants and trees can release carbon dioxide into the atmosphere, which accelerates the impacts of climate change, reducing the risk of severe wildfire can help maintain the whole forest for long-term carbon storage.

However, applying these techniques across 33 million acres of California forestland remains a monumental task. Prescribed burning requires a great deal of expertise and is also limited by weather conditions and air quality regulations. Meanwhile, mechanical tree thinning can be costly, and unlike timber harvesting, it does not generate any revenue for landowners — though Berkeley researchers have suggested that creating a market for small trees and other woody biomass could help offset the cost while limiting carbon emissions.

“Fire used to be so common in this system, and that’s no different than in most forests in California. But, when you take it out for that long, you begin this transformation,” Stephens said. “That’s why we have to get both public and private entities together to come up with a philosophy to be able to move forward on this. Blodgett is 4,000 acres — that’s interesting, but it doesn’t really address the needs of the state. We always hope that our work shows people what’s possible and then enables them to continue it.”