California’s giant sequoias are being destroyed by our wildfires. Scientists are resorting to extraordinary methods to save them
SPRINGVILLE, Tulare County — Dust kicked up from a fire-scarred forest floor as a dozen men shouldered bags of bright green seedlings they hoped would give rise to the largest trees in the world — an ascent the workers will not live to see.
The crew, trudging on a recent morning through the Mountain Home State Demonstration Forest on the west slope of the rugged southern Sierra Nevada, has an ambitious goal. In three weeks, it will plant 200,000 trees, many of them first-year giant sequoias.
But the broader mission of the group, and a coalition it belongs to, is even more extraordinary, representing a test of human intervention in a natural world changed by human hands.
The collection of foresters, scientists and land managers is trying to rebuild the ancient sequoia stands lost in California’s historic wildfires and ensure survival of the hallowed giants.
“These trees were on the landscape for 2,500 years, and then, in a 30-minute firestorm, they were gone,” said Jim Kral, the forest manager who is overseeing restoration of the charred Mountain Home Grove, about 90 miles southeast of Fresno. “These forests are cherished, and I think society wants the burned acres to be forested again, and we’re going to do everything in our power to do that.”
Over the past two years, fires destroyed nearly a fifth of the world’s sequoias, scientists estimate. The long-lived giants, which can soar to 300 feet tall and bulge 30 feet at their base, grow in only about 75 groves in the Sierra, mostly in an area bounded by Yosemite National Park on the north and Sequoia National Forest on the south.
Once considered virtually immune to burning because of their thick bark and lofty canopy, the trees had never before seen such intense blazes. Driven by a climate warmed by the burning of fossil fuels as well as decades of misguided fire suppression that built up vegetation, the burns have been bigger, hotter and ultimately lethal for the titans.
Acknowledging these causes, many forest managers feel compelled to step in. They worry not only about the loss of the sequoias as icons of the forest, but also about their capacity to soak up heat-trapping carbon and provide unique habitat for fishers, martens, owls and other rare wildlife.
“It’s my preference to let systems recover on their own,” said Christy Brigham, chief of resources management and science at Sequoia and Kings Canyon National Parks and one of the leaders in the coalition working to restore the fire-ravaged sequoias. “But there are limited groves, and we know that nature is dynamic, and we’re applying a lot of new stressors today.”
Mads Miller, with a research team from University of Nevada at Reno, sorts colored markers for variations of five tree species to be planted in Mountain Home State Demonstration Forest outside Springville (Tulare County).
Mads Miller, with a research team from University of Nevada at Reno, sorts colored markers for variations of five tree species to be planted in Mountain Home State Demonstration Forest outside Springville (Tulare County).
Carlos Avila Gonzalez/The Chronicle
State, federal, tribal and private land managers are now pursuing nearly a dozen sequoia reforestation projects across the Sierra. At Sequoia National Park, scientists plan to transport seedlings by helicopter into remote wilderness. At the Tule River Reservation, planting is expected to begin soon. The nonprofit Save the Redwoods League, on its private holdings, has already begun introducing trees.
The project at the Mountain Home Grove, run by the state’s Cal Fire agency, is the first big venture to launch.
While forest managers are optimistic their nascent efforts will help re-establish the trees, perhaps not today but in few hundred years, they’re not naive about the challenges. No one has ever grown sequoias in the wild at this scale and the methodology of re-engineering the forests is unproven. Some environmental groups are voicing opposition.
There’s also the question of whether trees planted today, borne from seeds tendered by the giants of the past, will produce trees fit for tomorrow’s even warmer, drier climate.
A contract worker hired by the state prepares a seedling to be planted on a ridge in Mountain Home State Demonstration Forest.
A contract worker hired by the state prepares a seedling to be planted on a ridge in Mountain Home State Demonstration Forest.
Carlos Avila Gonzalez/The Chronicle
The 5,000-acre Mountain Home Grove, one the largest stands of sequoias, looks little like the lush, mythical forest it once was.
In 2020, the SQF Complex fires ripped through, an outgrowth of the lightning-sparked Castle Fire, with flames so high and heat so fierce that the crowns of trees were toppled and the protective bark gutted. Unlike previous fires in the grove — which weren’t fatal and thus provided the benefit of helping release sequoia seeds from cones and clearing the ground for seedlings — this one left many areas essentially lifeless.
With blackened, wobbly trunks at risk of collapse, the state forest remains closed to the public. Many of the giants that endured, some dating to the Roman Empire, sport crispy brown tops.
The problem here, as in other groves that burned during California’s biggest-ever fire season two years ago, is that vast swaths of land didn’t yield a new crop of sequoias. Instead, the sun-soaked soil stands to be taken over by grasslands, shrubs and oak trees.
“I think it would be irresponsible to leave the ground fallow and see what happens,” said Kral, before climbing a hill where the shrubby ceanothus had already begun to emerge.
Forest managers in the Sierra had hoped that even with so many dead sequoias — as many as 10,600 mature trees across the range in 2020, then another roughly 3,000 in 2021 — the conifers’ cones would have dropped enough seeds to produce the next generation of trees. Drought conditions, though, stunted reproduction last year, and scientists worry the same might happen this year.
In many spots, seeds simply didn’t germinate because there wasn’t enough snow and cold during winter to help crack the shells. In other spots, sequoia seedlings sprouted in spring, sometimes in thick carpets, but summer proved too hot and dry for the young trees to hold on.
At Sequoia National Forest and the jointly administered Sequoia National Monument, which border the Mountain Home Forest, 90% of seedlings within 10 groves that burned in the SQF Complex are estimated to have died.
“There was just no moisture and then the temperatures got unusually hot, and that just desiccated them,” said Gretchen Fitzgerald, ecosystem staff officer for the national forest.
While a multiyear drought like the one that is currently gripping California wouldn’t have been a concern in the past, since mature trees offer a continuous source of seeds, many adults are no longer around to create the opportunity for offspring.
This weekend, Fitzgerald was scheduled to lead a small planting at the Sequoia National Monument’s burned Alder Creek Grove, home to the world’s fifth-largest sequoia. The project is the first of a handful of reforestation work planned by the U.S. Forest Service over the next two years.
Hired at the start of last year to help re-establish the trees, Fitzgerald worries about the future of the sequoias, saying, “There’s a lot that’s new and different today.”
A Giant Sequoia cone found in Mountain Home State Demonstration Forest outside Springville, Calif., on Tuesday, April 26, 2022. Around the state, crews and research teams have been planting trees to as parts of reforestation projects that both seek to replenish trees in burn areas as well as determine which trees and variations of those trees will grow better and resist fire and climate change.
A giant sequoia seedling planted next to a burned out stump in Mountain Home State Demonstration Forest outside Springville, Calif., on Tuesday, April 26, 2022. Around the state, crews and research teams have been planting trees to as parts of reforestation projects that both seek to replenish trees in burn areas as well as determine which trees and variations of those trees will grow better and resist fire and climate change.
Left: A giant sequoia cone. Right: A giant sequoia seedling planted next to a burned-out stump. Photos by Carlos Avila Gonzalez / The Chronicle
In the Mountain Home Grove, not far from where the crew was putting in seedlings, a team of researchers was preparing for another planting, this one part of a pioneering effort to determine which trees will survive best in the changing climate.
The team has been monitoring seedlings of giant sequoias, as well as four other conifers, sourced from seeds collected in different and often extreme environments across California. The experiment, marked by colored flags denoting tree types and seed origin, is only a year old, but the researchers hope to soon have insight into the optimal genetics for future trees — and put that information into action.
“When you’re talking about planting seeds now, you want them to be alive years from now, thousands of years from now in the case of a sequoia,” said Sarah Bisbing, a forestry professor at the University of Nevada in Reno and head of the Sierra Nevada Adaptive Management Experiment. “With rapid climate change, planting local seed lots is not the most successful strategy.”
Generally, scientists expect trees from farther south and lower elevations, as well as those accustomed to greater variability in winter, to produce seeds most viable for the hotter, drier climate ahead.
So far, foresters have not turned to genetics while rebuilding most of the sequoia groves, including Mountain Home. Seeds collected on site are primarily being used, and nothing is being planted outside the tree’s historical footprint. But this could change.
Many of the land managers involved in the restoration efforts say they’re open to assisted gene flow, or moving seeds within the range of the tree, as well as assisted migration, moving seeds and trees to entirely new locations.
“This has become increasingly more accepted as we see firsthand the impacts of climate change,” Bisbing said. “But it is something that still borders on controversial.”
In Sequoia National Park, even the effort to introduce seedlings grown mostly from locally collected seeds is encountering opposition. Hundreds of letters have poured into park officials critical of the plan to fly 12,000 young sequoias by helicopter to the Board Camp Grove above the South Fork of the Kaweah River for planting. The area also burned in the SQF Complex.
Opponents, which include conservation groups Wilderness Watch and Sequoia ForestKeeper, say such “ecological manipulation” is not suited to natural lands — and won’t be effective.
The National Park Service, however, contends that without action, the 48-acre Board Camp Grove could cease to be a sequoia forest. Moreover, park officials maintain that humans are already tinkering with the fate of the wilderness.
As isolated and undeveloped as Board Camp Grove is, it has witnessed a history of intervention in the form of wildfire suppression. More than 70 lightning-started blazes have been extinguished in the area by fire crews over the past 90 years, according to park figures.
Brigham, the resources management chief, says the fires, if left to burn, could have cleared out flammable vegetation and made the trees more resilient to future flames.
“The reason the fire burned this way and damaged the grove,” Brigham said, “is human action.”
A grove of sequoia trees in Mountain Home State Demonstration Forest shows the majesty of the ancient giants.
A grove of sequoia trees in Mountain Home State Demonstration Forest shows the majesty of the ancient giants.
Carlos Avila Gonzalez/The Chronicle
At the planting site in the Mountain Home Grove, the state-contracted forestry crew had put 11,000 seedlings in the ground by lunchtime, many of them giant sequoias.
The crew’s formula for speed is to hustle up the mountainside with trees, use a tool known as a HoeDad to make a hole, insert the seedling, and then promptly repeat.
The men planted ponderosa and sugar pine, also pieces of the area’s original forest, alongside the sequoias. Once in the ground, the roughly 10-inch seedlings stood about 10 to 12 feet apart. The plan is to grow the trees in this array over a little less than 600 acres, and do it again next spring.
“In three or four years, it’s going to start looking green again,” said crew foreman Roman Aguilar, as he stood on a high ridge where he could observe his workers slipping trees into the soil.
Assuming no disastrous heat over the next few months and, with some luck, a little rain, the initial success rate of the sequoia seedlings could be 75% or higher. The trees are known to be stout and fast-growing, which explains why they blossom into the biggest living things on the planet.
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Going forward years and decades, many of the sequoias will die. At the Mountain Home Grove and other areas with new plantings, land managers intend to light intentional burns and manually thin trees to prevent overcrowding and boost forest health. The sequoias that are lost, though, will have served the purpose of muscling out other vegetation and helping establish a grove fit for their peers.
“We’re going to be speeding a new forest going up by a few thousand years,” forest manager Kral said of the planting and the follow-up stewardship.
While Kral is confident in his restoration plan — and expects the young trees to survive at least the near-term swings in climate — his concern is another monstrous wildfire.
Forests with smaller trees, and those lacking the diversity provided by unevenly aged trees, are generally a lot less robust. That leaves the Mountain Home Grove and other stands scheduled for restoration in the Sierra particularly vulnerable to burning.
“That’s the thing that scares me right now,” Kral said. “I hope my crystal ball is screwed up, but I think it’s reasonably foreseeable a fire is coming, and it’s going to be equally, if not more, damaging than the last one. I hope I’m wrong.”
Kurtis Alexander is a San Francisco Chronicle staff writer. Email: kalexander@sfchronicle.com Twitter: @kurtisalexander