California needs to abandon the idea that trees are always worth saving and that fire is always a threat. Instead, it should let modest wildfires burn.

The West Coast is battling devastating wildfires again this year. Here’s a look at how forest management plays a role in the spread of such wildfires, first published in 2018.

The photograph below shows the Yosemite Valley in 1899 on the left, with open meadows and a patchwork of large conifers.

On the right is the same view in 2011. The valley floor has many more trees.

Which forest do you think is healthier?

If you picked the sparser forest from 1899, you’re on the right track.

Much of California’s forestland is overgrown, partly because of federal regulations implemented in 1910, which mandated stamping out wildfires as soon as possible. These policies were revised around the 1970s to allow some fires to naturally burn their course, but much of the West has struggled to do so.

At the height of 2018’s devastating wildfires, President Trump tweeted that there was “no reason” for the fires besides “gross mismanagement” by the state. Critics took issue with the timing and simplistic logic of the statement, but the comment drew attention to the way forest management affects the frequency and intensity of wildfires. Ecologists and forest experts attribute California’s destructive wildfires to decades of aggressive fire suppression, in addition to the increased population of fire-prone areas and hotter, drier conditions due to climate change.

The solution needs to address all these things, but one critical step is shifting our understanding of fire’s role in forest ecology. Policymakers and citizens alike must abandon the idea that trees are always worth saving and that fire is always a threat. Instead, they should permit modest, ecologically necessary wildfires to burn.

“For a long time, we were mistaken about what was going on in the forest,” said Malcolm North, an ecologist with the U.S. Forest Service. “People believed that you needed to put fires out because it was burning the forest up. That has proven to be wrong.”

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Roughly one-third of the 100 million acres that make up California are covered in forest. Before Euro-American settlement in the 1800s, fires burned about 1.5 million acres of forest each year, on average, according to an analysis of fire return intervals by Scott Stephens, a professor of fire science at the University of California, Berkeley. Skies were most likely smoky through much of the summer and fall, and most forests in California burned every five to 25 years from wildfires caused by lightning or Native American burning practices, he said.



These small fires benefited the entire forest ecosystem, returning nutrients to the soil by burning old vegetation and encouraging new growth by allowing sunlight to reach the forest floor. But between 1950 and 1999, fires burned just 57,000 acres on average each year under a sweeping fire-suppression policy. Forests that were once periodically cleared by less intense wildfires are now covered by “thick carpets of forest fuels,” according to a report by the Little Hoover Commission, an independent California oversight agency.



In the past two decades, California has begun to see the consequences. Wildfires are now burning much larger swaths of California each year. Forests across California have also grown much denser over the past 70 years, partly due to less frequent fires, but also because large, old trees have been harvested by loggers. In their place are numerous young, small trees of species that can tolerate the shade from thicker canopies and are easier to burn because of their thinner bark and slimmer trunks. Decreasing the amount of fuel available to wildfires requires a combination of practices that remove vegetation, like prescribed fires and the selective removal of smaller trees and mulching.



Stephen Pyne, an environmental historian who studies fire, emphasized that logging would not keep wildfires at bay. “Logging takes the big trunks and leaves the small stuff because there’s no market for it,” he said. “Fire burns the little and leaves the big.” Making matters more complicated, more than 11 million Californians live in the wildland-urban interface, fire-prone transition zones between unoccupied land and developed areas. Because the majority of wildfires are caused by human activity, the growth since 1990 of these transition zones is troublesome.



The presence of people in these areas makes it difficult to conduct prescribed burns. It also increases the odds of deadly wildfires starting because of the proximity of buildings and flammable vegetation to ignition sources like sparking power lines, cigarettes and campfires. Many wildfires in the past decade have occurred in and near the areas where forest meets human development. Approximately 6.9 million acres burned in California wildfires from 2008 to 2017. Over the same period, there were far fewer prescribed fires, which are intentionally set by fire managers to mimic the natural cycle of wildfire. They burned about 250,000 acres, a conservative estimate according to CalFire, the state agency responsible for fire protection in forests. Patchwork forest ownership further complicates the application of fire-prevention strategies. State and local governments own only 3 percent of forestland. Federal agencies own 57 percent. Almost 40 percent is owned by private landowners, most of whom own small tracts of land, lack the expertise to conduct prescribed burns and are reluctant to be held liable if the fire gets out of control.



CalFire is seeking to address these challenges by streamlining the permit and planning process and training more personnel to conduct burns. Researchers like Greg Asner, an ecologist at the Carnegie Institution for Science, are working to understand how the shift toward a hotter, drier climate in California is escalating tinderbox-like conditions and stressing densely packed trees already competing for water.



More than 120 million trees have prematurely died in recent years, according to the Forest Service. Dr. Asner estimated this is a tenth of the state’s trees. The large amount of combustible dead wood increases the risk of severe fire.

California will have to collect itself once again after another destructive and deadly wildfire season. But recovery is not just about donating to relief efforts and rebuilding burned homes. It’s also about creating a new culture for forest and fire management in the state, one that respects the role that carefully planned fires play in preventing disasters.

In May 2018, then-Gov. Jerry Brown took a step towards this future, dedicating $96 million to reducing wildfire risk in the state. He directed state offices to double the number of acres being managed with prescribed burns and vegetation thinning to 500,000 acres from 250,000 acres, among other directives like educating landowners about effective forest management.