Controlled burns emerge as key strategy to save giant sequoias

For decades, the instinct was to fight every forest fire. But in the case of the giant sequoia, that instinct may have been misplaced. New research and on-the-ground results are pointing to a counterintuitive truth: the best way to save these ancient trees is to let more fire burn.

Fire as a life-giver

Giant sequoias evolved with fire. Their thick, spongy bark protects them from low-intensity flames, and their cones need the heat of a fire to open and release seeds. For millennia, natural fires cleared the undergrowth and created the perfect conditions for sequoias to regenerate.

But modern fire suppression changed the equation. By putting out every small fire, forest managers allowed dense vegetation to build up. When fires finally ignited, they burned hotter and higher, climbing into the canopy and killing trees that had survived for centuries.

Megafires turn the tables

Recent megafires in California have proven devastating. In 2020 and 2021, wildfires killed an estimated 10 to 14 percent of the world's giant sequoia population. The Castle Fire alone destroyed more than 7,500 mature sequoias.

The difference between a beneficial fire and a deadly one comes down to intensity. A slow, low flame clears the forest floor. A raging crown fire cooks the trees from above. The goal is to return fire to the ecosystem before nature does it with catastrophic force.

Controlled burns show results

Prescribed burns have now saved thousands of giant sequoias from megafires. Researchers from UC Davis, Yale, and other institutions have documented the success of these controlled operations. In areas where managers deliberately set low-intensity fires, the trees survived later wildfires that would have otherwise killed them.

The strategy is not new. Native American tribes regularly burned portions of the Sierra Nevada for thousands of years. But the practice was largely abandoned in the 20th century. Now, forest managers are reviving it with modern techniques.

One key finding: the areas that received controlled burns in the years before the recent megafires saw dramatically lower tree mortality. The fires cleared the ladder fuels that allowed flames to climb into the canopy, and the sequoias themselves were left standing.

Shifting public perception

Despite the evidence, prescribed burning faces challenges. Smoke from controlled burns can affect air quality in nearby communities. There is also the risk that a controlled burn could escape its intended boundaries, especially in dry, windy conditions.

Public perception has been slow to change. Many people still see all fire as destructive. But scientists and land managers are working to educate the public that fire is a natural part of the sequoia's life cycle — and that suppressing it entirely only leads to worse fires later.

California has begun investing in prescribed burn programs, but the scale remains limited. Experts say millions of acres need treatment. The window to act is narrowing as climate change dries out forests and extends the fire season.

What comes next depends on whether policy can catch up to science. The giant sequoias have survived for thousands of years. Whether they survive the coming decades may hinge on our willingness to light the match.