Global Courant
When my colleagues and I recently hiked through the giant sequoia forest of Nelder south of Yosemite National Park, we could hardly believe our eyes. In 2017, the railway fire raged through almost all of Nelderbos, burning lightly in most areas about six years after the fire, but very intense in the part where we walked. The naturally regenerating giant sequoia forest was so vigorous and lush that in many places we had to pull apart the stems of young sequoias to walk among them. There were hundreds of them on almost every acre – many of them were already 8 or 9 feet tall.
It was a remarkable sight, because at that particular location, the railroad fire burned hot, killing trees, including about three dozen mature redwoods. This high-intensity burn spot is insulated; it’s nearly half a mile from the forest’s nearest remaining living, mature redwoods. How was the extraordinary rejuvenation of giant sequoias possible there?
The US Forest Service, which manages Nelder Grove and many other redwood forests, repeated to the public, the media and Congress that giant sequoias are adapted to mild and moderate surface fires. The agency has insisted that emergency action is needed in redwood groves to save the trees from high-intensity fires and ensure that only lower-intensity fires occur. Those emergency measures could take the form of bulldozing, chainsaws and logging, without using the usual environmental safeguards, when legislation is pending – the deceptively named Save our redwood law, introduced by House Speaker Kevin McCarthy (R-Bakersfield) — passes in Congress. In the meantime, Staatsbosbeheer is already continuing with felling plans in the Nelderbos, based on this “emergency situation”.
But the evidence on the ground in the Nelder Grove and other fire areas contradicts the narrative that lower-intensity fires are the only good fires. Is it possible that we are completely wrong when it comes to giant sequoias and wildfires?
Coincidentally, some of the U.S. Forest Service’s own scientific studies explored that question years ago, indicating that mixed-intensity fire, not logging, is the answer to giant sequoias. However, for an agency still focused on selling public trees to private logging companies and keeping revenue within budget, that can be an uncomfortable answer.
For example, in 1994 Staatsbosbeheer has a study discovering that the agency’s successful elimination of wildfires for more than a century was actually killing redwood groves and threatening their survival. The old “monarch” sequoias slowly died out, and new sequoia seedlings and saplings were almost completely absent, resulting in a “massive failure of sequoia propagation.” The study found that in order to maintain stable or growing populations, giant sequoias rely specifically on high-intensity fire in patches, pointing out that the “giant sequoia is a so-called ‘pioneer species’, requiring canopy-destroying disturbance to complete its life cycle.”
These intense wildfires melt the resins in sequoia cones, allowing them to release tens of thousands of seeds, while also creating more sunlight for the seedlings and consuming the thick layer of twigs and needles on the forest floor, turning it into a nutrient. -rich ash bed that helps young sequoias grow and bloom. Twelve years ago a Staatsbosbeheer study found a marked lack of redwood reproduction in low-intensity fire areas and high reproduction density in high-intensity fires. Controlling for homogeneous low-intensity fire and trying to prevent and exclude higher-intensity fires is like managing for the extinction of giant sequoias.
When the Washburn fire burned down part of Yosemite’s famous Mariposa redwood forest last year, it burned at low intensity where the park had previously caused prescribed burns. Park officials claimed success, based on the premise that reducing fire intensity is categorically a good thing for giant sequoias. But science has been telling us a more complex story for decades.
Of course, sequoias can’t just tolerate high-intensity fire either. We want a mix of low, medium and high, and that’s what we got in the Sierra. Despite reports of total decimation from high-intensity fires, my research, based on recent satellite imagery and ground surveys, indicates that the major wildfires from 2020 through 2021 killed about 8% of redwoods, not up to 20% as some have claimed.
An 8% loss sounds bad in itself, but it may be in line with what could have happened, of course, before the fire lockout of the 20th century. And just like in the Nelder Grove, where some patches of mature giant sequoia are ablaze from high-intensity fires, there will likely be hundreds of saplings for every dead one.
If we really care about giant sequoia forests, the way forward shouldn’t be mandatory emergency powers that circumvent environmental laws and public participation, powers that could unleash potentially destructive logging. The Save Our Sequoias Act is wrong, and therefore it is strongly opposed by more than 80 environmental organizations.
No, to have healthy, vibrant giant sequoia forests in the future, we need some humility and some respect for a species that over 90 million years has developed an interdependent relationship with mixed-intensity wildfires. Above all, we will have to come to appreciate and accept the dynamic forces of wild nature, such as wildfires, which may seem alarming to us, but which also shape and nurture giant sequoia forests and many other fire-adapted ecosystems on the planet.
We must learn to see the beauty in the burn.
Chad Hanson is an ecologist and director of the John Muir project. He is the author of “Smokescreen: debunking wildfire myths to save our forests and climate.”
