Nov 19, 2021 - Energy & Environment

California wildfires killed at least 3% of all giant sequoias this year

A fire burning through the Long Meadow Grove of giant sequoia trees in Sequoia National Forest on Sept. 21.

A fire burning through the Long Meadow Grove of giant sequoia trees in Sequoia National Forest on Sept. 21. Photo: David McNew/Getty Images

California wildfires killed between 3% and 5% of all giant sequoias this year, the National Park Service announced in new estimates on Friday.

Why it matters: The service said this level of devastation increases the risk of regeneration failure occurring in parts of Sequoia National Park, meaning the sequoias will be unable to naturally regrow.

By the numbers: NPS estimates that the KNP Complex and the Windy Fire destroyed between 2,261 and 3,637 sequoias over four feet in diameter in Sequoia and Kings Canyon national parks this year, representing 3% to 5% of the estimated total population of the trees in 2021 (~75,580)

  • These losses come on top of the mortalities from the Castle Fire in 2020, which destroyed 10% to 14% — between 7,500 to 10,600 — of all large sequoias.
  • The KNP Complex alone burned through 16 sequoia groves, while the Windy Fire tore through 11. In total, 6,109 acres of grove were burned this year.
  • These trees are ancient, as sequoias — many of which are among the largest trees by volume on Earth — can take decades to grow to over four feet in diameter.

Because of this year's losses, combined with damage from fire events last year and between 2015 and 2017, park officials are concerned the trees will struggle to naturally regenerate in certain parts of Sequoia National Park.

  • Average fires typically help giant sequoias and other trees reproduce, as they allow the trees to release their seeds and prep the soil by burning off undergrowth.
  • But extremely hot fires can burn up the seeds, damaging the species' ability to regrow. Erosion after devastating fires can also carry the seeds into areas in which they are unable to grow.
  • NPS identified 436 acres in and around Sequoia National Park as being vulnerable to total sequoia loss if regeneration from seeds that survived the KNP Complex is inadequate.
  • If it is, the park service may have to reforest around 350 of the acres.

Thought bubble, via Axios' Andrew Freedman: The damage to the massive and wondrous sequoia groves, which have withstood less intense fires for generations, underscores the ways that global warming is rapidly changing California ecosystems.

  • While the surviving sequoias will keep tourists coming and maintain the national parks, what has happened in the past two years is a trend that could continue, given climate change and long-term drought.

The big picture: Recent research has found that human-caused climate change is the main driver behind ongoing drought conditions and increased wildfire risk in the U.S. West.

  • Fourteen out of 20 of California's largest wildfires have occurred since 2010, with six out of seven happening since 2020.

Go deeper ... Poll: 52% of Americans say they've experienced effects of global warming

Go deeper