How California’s Redwoods are being revived

Not far away is a section that thinned 20 years ago, when the number of trees per acre was reduced to fewer than 300. The redwoods in this area are much larger in diameter and far more robust, the understory greener and more diverse.

“In the untreated forest, trees are not vigorous and are susceptible to stressors — fire, wind and bugs,” said Jason Teraoka, the forester. “But here with more diameter growth and crown growth, it’s a much more vigorous forest and less susceptible to disturbance.”

The thinned forest is part of a project called Redwoods Rising, which is aimed at creating old growth redwood forests for the future. Carried out by Redwood National and State Parks and the Save the Redwoods League, a nonprofit, crews are using chain saws and logging equipment, and planning prescribed fires, to mimic the traits of a young healthy redwood forest and undo the damage from decades of unbridled logging and indiscriminate reseeding. Treated forest stands, or communities of similar trees like this, researchers believe, will grow into the classic cathedral redwood groves over the next few centuries.

The effort is also a response to a changing world. “We are trying to restore these forests to be more resilient so they will be able to withstand a hotter and drier climate,” said Ben Blom, the director of stewardship and restoration for the Save the Redwoods League. “The logging left behind a forest that is very unnatural and unhealthy. We’re trying to make these stands as healthy as possible.”

Climate change and accompanying stressors

The conservationists and park officials also hope the work will help combat the effects of climate change. Redwoods take up and store more carbon than any other species of tree, largely because they are so tall — some reach heights of more than 350 feet — and so long-lived. Some are more than 2,000 years old.

California is home to the world’s only native coast redwood forest, which extends more than 450 miles from central California north to southern Oregon, and it is heading into a deeply uncertain future. A recent study found that the forest is drying as temperatures increase. Average summer temperatures in California have risen 3 degrees since the end of the 19th century.

“A lot of worries are centered around whether conditions are going to become so hot and dry the species won’t be able to persist,” said Steve Sillett, a professor of redwood forest ecology at Cal Poly Humboldt in Arcata, California, and lead author of the study. “My guess is that it will persist. It will just be shorter.”

Because of their height, many redwoods are at risk since they have to pump water hundreds of feet against gravity and friction. Hotter droughts in particular, like those that occurred here between 2012 and 2016, can stress trees to their breaking point.

Wildfires also pose greater risks as conditions become warmer. A goal of the thinning project is directed at giving trees enough room to enlarge their diameter with thicker bark, increasing their fire resistance. The wider spacing also opens up the forest floor to more light, fostering a vibrant ecosystem.

These coastal redwoods are faring better in a changing world than the other California redwood, the giant sequoia, in the foothills of the Sierras farther inland. Fires and insects are taking a toll. “We’ve lost 20% of the monarch trees,” Blom said, referring to the largest of the sequoias. “It is an existential crisis for the sequoias.”

Climate-driven changes in fire are affecting these forests, too. In 2020, lightning sparked a blaze that burned through Big Basin Redwoods State Park. “We saw behavior on that fire that none of us had ever seen in the coast redwood range,” he said. The crowns of many of the coastal redwoods there were destroyed.

A legacy of unchecked logging

The Redwoods Rising thinning project, which began in 2020 and has an annual budget of $10 million to $12 million, is also tackling the aftermath of unbridled helicopter reseeding by the timber industry that created the choke of subsequent redwood and Douglas fir forests of today.

Not all researchers believed that thinning was the best way to manage these forests. In a recent paper, Will Russell, a professor of environmental studies at San Jose State University, argued that removing large numbers of trees can compact the soil, invite invasive species and open up the canopy, which leads to higher temperatures.

Simply leaving the tracts alone, he said, makes more sense and will eventually result in a healthy redwood forest, even though it takes longer. “Lots of little sprouts can make people nervous because of the density of small trees that are there,” Russell said. However, “redwoods over time will overtop those and phase them out and the Douglas fir will eventually diminish in terms of their dominance. That can take a long time in human terms, but in the stands I’ve studied somewhere around 60 to 80 years is kind of a tipping point.”

Overgrown forests aren’t the only legacy of logging. Bulldozers carved up the landscape, leaving giant stumps and deep road scars behind. “Every tree had a road to it,” said Neal Youngblood, a geologist with the park service who is overseeing road removal. “They had roads everywhere. Every creek had roads going up both sides.”

And over them. “Humboldt crossings happened all over redwood country,” said Spencer Stiff, the operations manager for the league. The crossings refer to the makeshift bridges cobbled from trees knocked down by bulldozers and covered with dirt that allowed trucks and other equipment to cross the creeks. Left there after logging ended, the pathways are crumbling, bleeding sediment into the creeks and destroying fish habitat.

Some 22 miles of roads have been reclaimed in the parks as part of the project, and 300 miles remain for removal or treatment.

Redwood logging these days is a far cry from what it was. The clear-cutting of ancient trees has ended, although researchers say the current practice of logging second- and third-generation redwoods still poses environmental problems. “It’s vastly better,” said Mark Andre, a forestry consultant and manager of the Arcata Community Forest, which carries out sustainable logging. “In terms of impacts to fish and wildlife, there’s no comparison.”

There are other ways to ensure a future for the redwoods. Sillett proposes identifying “potential elder trees,” or second-growth redwoods, that have the best characteristics to become sky-scraping titans with vast, complex branches in their crown.

Hosting the greatest share of biodiversity, the crowns provide a home for large fern mats, the small ecosystems that can weigh hundreds of pounds and hold up to 5,000 gallons of water. Ferns, lichen and moss grow in them, and salamanders, spotted owls and bats reside in the trees.

The endangered marbled murrelet, an unusual brown and white oceangoing bird, lives at sea eight months of the year and only comes to land to nest, often in the branches of the redwood — where it lays a single egg. Its numbers have also declined because of logging and wildfires.

“We can identify these exceptional trees and promote them — by removing the competition,” Sillett said. “It’s about creating a tree that’s going to last for a thousand years, allowing a tree to reach its potential.”

This article originally appeared in The New York Times.