A massive fire in California last year may have destroyed up to a tenth of the world’s mature giant sequoia population, according to a draft report produced by scientists working for the National Park Service.
From August to December 2020, the Castle fire tore through Sequoia national park, burning through thousands of the ancient redwoods, the world’s largest tree. By the time the blaze was contained, it had consumed 175,000 acres of parkland. NPS scientists now estimate that between 7,500 and 10,000 mature giant sequoias went up in flames.
“I cannot overemphasize how mind-blowing this is for all of us. These trees have lived for thousands of years. They’ve survived dozens of wildfires already,” said Christy Brigham, the chief of resources management and science at Sequoia and Kings Canyon national parks.
Giant sequoias only grow in the peaks and valleys of a small central range of California’s Sierra Nevada. Because of the trees’ concentrated range, last year’s fire managed to literally decimate part of the world’s remaining population of the unique flora.
In recent months, researchers with the NPS have traversed the charred forests to survey the damage. In early May, some of these researchers discovered a trunk of one sequoia still burning, months after the rest of the fire was contained, and after an entire winter of rain and snow.
At that time, researchers did not yet know the extent of the fire’s damage. Now, a draft report shared with the Visalia Times-Delta newspaper, which first reported the news on Wednesday, reveals just how catastrophic the burn was.
Brigham, the study’s lead author, cautioned that the numbers are preliminary and the research paper has yet to be peer-reviewed. Beginning next week, teams of scientists will hike to the groves that experienced the most fire damage for the first time since the ashes settled.
“I have a vain hope that once we get out on the ground the situation won’t be as bad, but that’s hope, that’s not science,” she said.
In Sequoia national park, most of the older sequoias have survived fires across millennia. The giant trees are not only fire-adapted – they’re also fire dependent. Sequoias depend on low-intensity fires to help them release their seeds from waxy pine cones. However, in recent years, the climate crisis and a build up of fuels have led to high-intensity, out-of-control burns that threaten the survival of the groves.
“One-hundred years of fire suppression, combined with climate change-driven hotter droughts, have changed how fires burn in the southern Sierra and that change has been very bad for sequoia,” Brigham said.
For generations, Native people in California lit controlled burns as a part of land husbandry. However, in the first half the 20th century, the state and federal government worked to prevent fires in protected land like Sequoia. This led to a massive build up in fuel – dry and fallen timber and leaves.
As wildfires began to burn with an unnatural intensity, researchers in Sequoia and Kings Canyon began conducting controlled burns in the 1960s. These low-intensity fires clear out tinder on the forest floor and help the sequoias germinate. However, Brigham says that the current rate of intentional burns have not been enough. In the last few decades, officials have burned about 1,000 acres in controlled fires per year. Brigham estimates that it would take 30 times that number to return the forests to a healthy state.
The consequences of losing thousands of giant sequoias will reverberate across California – and the world – for decades. The ancient groves are habitat for native wildlife, and their root systems help protect the watershed that farmers in the state’s San Joaquin Valley depend on. Because redwoods remove and store carbon from the atmosphere at a nearly unrivaled rate, losing sequoia could intensify the climate crisis.
And the danger for the sequoias is far from over. With most of California in severe drought, the dryness of vegetation across the state has shocked officials who worry that this year’s fire season might prove historically devastating. 2020 saw five of the six largest wildfires in California history burn through the state, destroying millions of acres and blanketing much of California in noxious smoke.
The Associated Press contributed reporting