Safford examining damage from the 2021 Caldor Fire in Eldorado National Forest, California, near Lake Tahoe, in the United States. — AP
ON a steep mountainside where walls of flames torched the forest on their way toward Lake Tahoe in 2021, blackened trees stand in silhouette against a gray sky.
“If you can find a live tree, point to it,” Hugh Safford, an environmental science and policy researcher at the University of California, Davis, said touring damage from the Caldor Fire, one of the past decade’s many massive blazes.
Dead pines, firs, and cedars stretch as far as the eye can see. Fire burned so hot that soil was still barren in places more than a year later.
Granite boulders were charred and flaked from the inferno. Long, narrow indentations marked the graves of fallen logs that vanished in smoke.
Damage in this area of Eldorado National Forest could be permanent – part of a troubling pattern that threatens a defining characteristic of the Sierra Nevada range that naturalist John Muir once called a “waving sea of evergreens.”
Forests like this are disappearing as increasingly intense fires alter landscapes around the planet, threatening wildlife, jeopardising efforts to capture climate-warming carbon and harming water supplies, according to scientific studies.
A combination of factors is to blame in the US west: A century of firefighting, elimination of Indigenous burning, logging of large fire-resistant trees, and other management practices that allowed small trees, undergrowth and deadwood to choke forests.
Drought has killed hundreds of millions of conifers or made them susceptible to disease and pests, and more likely to go up in flames. And a changing climate has brought more intense, larger and less predictable fires.
“What it’s coming down to is jungles of fuels in forest lands,” Safford said.
“You get a big head of steam going behind the fire there, it can burn forever and ever and ever.”
Despite relatively mild wildfire seasons the past two years, California has seen 12 of its largest 20 wildfires – including the top eight – and 13 of the most destructive in the previous five years.
California has lost more than 4,560sq km – nearly 7% – of its tree cover since 1985. While forest increased in the 1990s, it declined rapidly after 2000 because of larger and more frequent fires, according to the study in the American Geophysical Union Advances journal.
A study of the southern Sierra Nevada – home to Yosemite, Sequoia and Kings Canyon national parks – found nearly a third of conifer forest had transitioned to other vegetation as a result of fire, drought or bark beetles in the past decade.
“We’re losing them at a rate that is something that we can’t sustain,” said Brandon Collins, co-author of that report in the journal Ecological Applications and adjunct forestry professor at the University of California, Berkeley.
“If you play it out (over) the next 20 to 30 years at the same rate, it would be gone.”
Some environmentalists, like Chad Hanson of the John Muir Project sponsored by the non-profit Earth Island Institute, said there’s a “myth of catastrophic wildfire” to support logging efforts – and he has often sued to block plans to remove dead trees or thin forests.
Hanson said seedlings are rising from the ashes in high-severity patches of fire and the dead wood provides habitat for imperilled spotted owls, Pacific fishers and rare woodpeckers.
Others are concerned failure to properly manage forests can result in intense fire that could harm wildlife habitat, the ability to store climate-warming carbon in trees and the quality of Sierra snowmelt that provides about 60% of the water for farms and cities.
Before the mid-1800s, fire sparked by lightning or set by Indigenous people burned millions of hectares a year.
It kept undergrowth in check, allowing low-intensity flames to creep along the forest floor and remove smaller trees competing with big ones.
But after settlers drove out Native Americans and logged forests, fighting fires became the mission to protect the valuable trees – and, increasingly, homes built deeper into wildlands.
In 1935, the US Forest Service established a policy to knock down any fire by 10am the next morning.
That has allowed forests to become four to seven times more densely wooded than they once were, Safford said.
While many larger, fire-resilient trees like ponderosa and Jeffrey pines were logged for lumber, smaller trees that are not so fire resistant have thrived.
They compete for water and their low branches allow fire to climb into the canopy of taller trees, fuelling devastating crown fires.
The Caldor Fire, which destroyed 1,000 structures while burning across the Sierra Crest and into the Tahoe basin, torched forest that hadn’t seen flames in over a century, Safford said.
Years of drought fuelled by a warmer climate had made it a tinderbox.
Swathes of Eldorado National Forest burned at such intensity that mature pines went up in flames and their seeds were killed.
Unlike species such as giant sequoias and lodgepole pine that drop their seeds in fire, the dominant pines of the Sierra can’t reproduce if their seeds burn.
Manzanita and mountain whitethorn – chaparral typical at lower elevations in California – take root in ashes and can dominate the forest.
To tackle the problem of huge wildfires, the federal government, which owns nearly 60% of California’s 134,00sq km of forest, agreed to reduce fuels on 4,040sq km a year by 2025.
Fire scientists advocate more deliberate burning at low-to-moderate severity to clear vegetation that makes forests susceptible to big fires.
But the Forest Service has historically been risk averse, said Safford, the agency’s regional ecologist for two decades before retiring in 2021.
Instead, the Forest Service plans to ramp up forest thinning in places where the wildfire threat to communities and infrastructure is most immediate.
Last fall, when Safford led two graduate students up a rutted fire road through charred forest, they came upon a patch of life where large pines and cedars towered overhead and seedlings sprouted.
A “nirvana” is what Safford called it.
Smaller fire-intolerant trees had been harvested and other vegetation removed before the fire.
The space between the trees allowed the fire to creep along the ground, only charring some trunks.
Susan Britting, executive director of Sierra Forest Legacy acknowledged any cutting triggers scepticism because loggers historically took the largest, most marketable trees.
But she said thinning trees up to a certain diameter is acceptable, though she prefers prescribed burning.
“In my experience, things like logging, tree removal, even reforestation, those things happen,” Britting said.
“The prescribed fire that needs to happen... just gets delayed and punted and not prioritised.”
The chance of a deliberate burn escaping its perimeter – as happened last year in New Mexico’s largest fire in state history – remains a big challenge.
Safford – now chief scientist at Vibrant Planet, an environmental public benefits corporation – acknowledged larger trees have been logged in the past but said that’s not now envisioned in thinning projects.
Even with chainsaws, we won’t be able to cut our way out of the problem, he said.
Two-thirds of the rugged Sierra is inaccessible or off-limits to logging, so fire will have to do much of the work.
But there’s a backlash. Homeowners are anxious prescribed fires will jump perimeters and destroy houses.
“It’s the classic wicked problem where any solution you derive has huge implications for other sides of society and the way people want things to be,” Safford said.
“So I’m afraid what’s going to happen is at some point we’ll burn all of our forests.” — AP
