Ancient trees need fire to reproduce, but wildfires are killing them

A new scientific study has revealed the current state of California's giant sequoia range, revealing the alarming extent of damage that has been caused to them by extreme wildfires over the last decade.

A study published in the journal Fire Ecology on March 27, 2026, revealed that approximately 17% of all mature giant sequoias have been killed by wildfire since 2015 with most loss occurring in the megafires of 2020 and 2021.Titled 'The State of the Giant Sequoias: Losses, Risks and Opportunities, ' the research from the Giant Sequoia Lands Coalition (GSLC) explained that most of the world's remaining giant sequoia groves do not currently meet a high level of resilience to extreme wildfire.

With shifting climates increasing wildfire risk and severity, more work is needed to protect these groves.Due to a combination of forest treatments and natural-intensity wildfires that have occurred throughout the sequoia range since 1995, scientists determined that only 26% of existing sequoia grove area has high resistance to extreme wildfire. Other groves display moderate resistance (38%), low resistance (2%) or have no resistance at all (16%).

The remaining 18% of the grove area has been lost to high-intensity fires that have also inhibited postfire regeneration in some locations; while this percentage tracks total grove area lost since 1984, 17% of this 18% has been lost in just over the past decade.“While the results of our study are sobering, they position us to direct our attention toward the groves most in need of restoration,” said Kristen Shive, PhD, assistant professor of cooperative extension at UC Berkeley’s Department of Environmental Science, Policy and Management, who led the study on behalf of GSLC.

“Megafires have claimed so many mature sequoias in recent years, and because sequoias need fire to regenerate, we once thought this would be a silver lining.

We now know that, in some cases, fires were so severe that even this fire-loving species isn’t regenerating. With about 13% of the range at some risk of local extinction, the Coalition’s work to make sequoia groves more resilient to extreme wildfires has never been more important.

We will continue to use science to guide our efforts to protect these iconic trees from vanishing.”

Sequoia trees: The trees that reproduce with fire

Giant sequoias are the world’s most massive trees and can live for thousands of years.

Giant sequoias are the world’s most massive trees and can live for thousands of years. These ancient trees store considerable amounts of carbon and provide essential habitat for wildlife across approximately 25,000 acres along the western slopes of California’s Sierra Nevada Mountains.Interestingly, they cannot reproduce without fire. Sequoia cones can stay closed and hold seeds for up to 20 years.

But the heat from a fire makes the cone's scales dry up and bend backwards so the seeds fall out. They also need bare dirt to sprout and fire burns up dead leaves and needles on the forest floor to create this clear, ashy soil. This leaves behind a perfect bed of mineral-rich soil and sunny patches where the tiny seeds can grow.

Restoring the sequoia trees

With 2026 expected to be exceptionally warm, chances are high that dry conditions will amplify the severity of potential wildfires.

Since 2022, GSLC partners have implemented ongoing restoration in 44 out of the remaining 94 sequoia groves through resilience treatments, prescribed burns and the planting of native seedlings.

These restoration activities help shield these ancient groves from the impact of extreme wildfires and bolster the sequoia range’s total health. In 2025 alone, the Coalition treated 4,508 acres across 25 groves.The Coalition is prioritising restoration activities in the most vulnerable sequoia groves identified in the report. Restoration activities include the expansion of cultural and prescribed burns to boost wildfire resilience, continued active resilience treatments and ongoing monitoring of seedling growth in areas struggling with post-fire natural regeneration. The 2025-26 winter was the warmest on record in the Sierra region, leaving the winter snowpack—which giant sequoias rely on for most of their water—far below average.

With 2026 expected to be exceptionally warm, chances are high that dry conditions will amplify the severity of potential wildfires.