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Recent years have seen some of the largest wildfires in California鈥檚 history, and one of the best approaches to limiting their damage is controlled burns that reduce natural fuel for the fires. But now, it seems these burns are destroying the state鈥檚 iconic sequoia trees.

Giant sequoias (Sequoiadendron giganteum) have been dying off since the early 1900s because of fire suppression. These rare trees benefit from natural fires, because they rely on high heat for seed dispersal.

Californians frequently build communities in fire-prone areas, which can lead to devastating results if fires aren鈥檛 managed. That is why controlled burns, intended to clear dead trees, are so vital. If that fuel is gone, the thinking goes, fires will be less intense and easier to control.

But at the John Muir Project, a non-profit that works to protect public forests, and his colleagues found that this approach is destroying the state鈥檚 rare sequoias. They studied Nelder Grove in the Sierra National Forest, which hosts about 65 mature sequoias. This patch of towering trees was hit hard by the 2017 Railroad Fire, but now a new generation of sequoias is growing in places where that fire burned most intensely. In 2023, the researchers entered the burn zones and measured post-fire sequoia reproduction, heights of sequoia saplings, shrub cover and distance to the nearest live, cone-bearing sequoias. They did this in 23 plots.

鈥淲e found giant sequoia reproduction was the densest, tallest and most dominant, relative to other conifers, in the high-intensity fire patches, compared to lower-intensity fire areas,鈥� says. Hanson. 鈥淭his is really encouraging.鈥�

This may also have benefits for future fire prevention as well. 鈥淲ildfires spread more slowly and often less intensely through denser forests with more biomass and more vegetation because those areas have a cooler, shadier, more moist microclimate,鈥� he says.

Federal fire protection plans may be impairing the trees鈥� protective abilities. Commercial logging by the National Park Service and US Forest Service, intended to thin trees, can prevent sequoias from reproducing. Hanson says his team counted dead saplings in the path of logging machinery and found that heavy machinery killed 83 per cent of the young giant sequoias in the plots they surveyed.

, author of The Ghost Forest, says a lot of this logging is geared towards creating wood pellets for biomass energy production, not simply for wildfire protection. 鈥淣atural sequoia regeneration should be allowed to take its course,鈥� he says.

Hanson says we can strike a balance to save trees and protect people living near them. Pruning of vegetation within 30 to 60 metres around homes can help. Beyond that, 鈥渧egetation management provides no additional benefit to community safety and in many ways puts communities at greater risk by creating conditions that spread fires faster toward towns, giving people less time to evacuate鈥�, he says.