A new University of California, Davis study reveals that giant sequoias exposed to prescribed burns within the previous 10 years were nearly four times more likely to survive the 2020 Castle Fire and 2021 KNP Complex Fire than untreated trees, highlighting controlled fire as a critical conservation tool.
California’s ancient giant sequoias, some standing over 300 feet tall and surviving for more than 3,000 years on the western slopes of the Sierra Nevada, evolved in a landscape shaped by periodic, low-intensity fires. Their thick bark and elevated canopies historically offered protection against small, natural blazes that cleared underbrush and recycled nutrients. Decades of fire suppression, however, allowed dead wood, shrubs, and other combustible material to accumulate, transforming modern blazes into destructive megafires.
The catastrophic fire seasons of 2020 and 2021 proved devastating for the iconic species. Together, the Castle Fire and the KNP Complex Fire destroyed nearly 20% of the world’s mature giant sequoia population across the Sierra Nevada. As noted in coverage published in Yale E360, those two fires wiped out as many as 13,000 large sequoias, leaving scientists and land managers searching for effective ways to protect the remaining groves.
How Prescribed Burns Altered Survival Rates in Sequoia Groves
A multi-institutional study published in NASA demonstrates that proactive forest management significantly changes survival outcomes. Researchers analyzed data on approximately 26,400 individual giant sequoias across 19 groves within Sequoia and Kings Canyon National Parks, which have maintained extensive prescribed fire programs since the 1960s.
By combining airborne lidar, stem maps, high-resolution PlanetScope satellite imagery, and computer modeling, the research team tracked pre-fire fuel loads and post-fire outcomes.
“Prescribed burns are effective at reducing giant sequoia mortality, even for today’s extreme wildfires.”
Dan Dixon, lead author and postdoctoral researcher at the University of California, Davis
Computer simulations conducted during the study indicated that past prescribed burns directly prevented about 1,900 sequoia deaths during the 2020 and 2021 fires. Furthermore, the models suggested that if every sequoia in the affected groves had received similar treatment beforehand, another 3,900 trees might have survived.
Challenges in Expanding Controlled Burns Across California Forests
While scientific consensus points to controlled burns as an essential conservation tool, executing them safely grows more difficult as climate change lengthens the wildfire season and intensifies droughts. Higher temperatures and below-normal snowpacks leave forests increasingly dry and volatile.
“If the goal is protecting giant sequoias, prescribed fire is an essential tool available to managers.”
Dan Dixon, lead author and postdoctoral researcher at the University of California, Davis
Management efforts also carry inherent operational risks. As highlighted by Yale E360, U.S. Forest Service chief Randy Moore noted in an autopsy of an escaped prescribed burn in New Mexico that drought, extreme winds, and unpredictable weather changes continuously challenge the agency’s ability to utilize fire safely as a management tool.
To address these mounting pressures, diverse coalitions have formed to coordinate restoration. The Giant Sequoia Lands Coalition brings together federal, state, Tribal, and nonprofit organizations to coordinate restoration across the sequoia range.
Funding Sources and Future Forest Management Goals
