Redwoods stand tall as carbon traps
League finds regeneration also faster than other trees
A fervid new push is being made to protect and restore previously clearcut coast redwood forests after studies documented how they store more carbon than any other tree, a characteristic that researchers believe could be used as a bulwark against global warming.
The idea by Save the Redwoods League, a San Francisco nonprofit that has been the state’s most ardent defender of the giant trees since 1918, is to manage the cutover forests in a way that would augment growth, biodiversity and make the standing groves more economically valuable than they are as lumber.
“We’ve got one of the greatest tools at our fingertips in the fight against climate change,” said Sam Hodder, president and chief executive officer of the conservation organization. “We have learned that the redwood forest is already sequestering more carbon than any forest ever measured . ... The need for investment in our healing seems clear to restore the old growth of our future.”
The vision would require a huge collaboration among government, environmental groups, private owners, forest and wildlife biologists to improve the forest ecosystem in California, protect the wildlife that depends on it and rebuild surrounding habitat. Private property owners would have to buy into the plan, which would presumably call for ecotourism and other sustainable moneymaking opportunities.
It’s a daunting task,
considering how previously cut groves make up 95% of the redwood acreage in California and much of it is privately owned, including large groves owned by timber companies.
The latest studies, paid for by the Redwoods League over the past couple of years, confirm that oldgrowth redwood forests, some of which contain trees approaching 3,000 years old, sequester more carbon than any other type of forest in the world. More surprising, though, was how fast coast redwoods regenerate after being chopped down.
Steve Sillett, a botanist and professor in the forestry department of Humboldt State University, said that some of the regrowing secondgrowth forests, including one in Oakland, have, in 150 years or less, grown as large and now store almost as much carbon as oldgrowth trees.
His team climbed, measured and sampled 114 redwood trees ranging from 59 feet to 380 feet tall, and ranging in age from 115 to 2,340 years old. The secondgrowth study included oncelogged forests in Del Norte, Humboldt and Mendocino counties and in Oakland’s Reinhardt Redwood Regional Park, where five trees were studied, the tallest being more than 200 feet tall and 135 years old.
The study, published in the latest edition of Forest Ecology and Management, found that young redwood forests can accumulate biomass at rates even faster than oldgrowth stands — with trees surpassing 200 feet tall in less than a century.
The secondgrowth forests had 40% as much biomass and were storing 30% as much carbon as the original old growth, according to the findings. Some forests that were logged in the mid1800s have since accumulated as much as 339 metric tons of carbon per acre — the equivalent of taking about 270 greenhouse gasspewing vehicles off the road for a year.
“The key points are that the redwoods are the superlative species for sequestering carbon, and the second growth can recover a substantial portion of that in a few generations,” Sillett said. “They are doing an enormous amount of work” for the environment. “They are not just sitting there idle.”
Redwoods store at least three times more carbon than other types of trees and have unique decayresistant qualities in their heartwood that allows them to retain the climatewarming gases and prevent them from leaking out into the atmosphere, even after they die. Their many limbs and branches also sustain other plants and wildlife, many of which live high in the tree canopy.
It is why Save the Redwoods League ecologists believe the reconstruction of California’s once mighty forest ecosystem is so important.
Reinhardt is one of several Bay Area groves covering 2,500 acres around Redwood, San Leandro and Moraga creeks where the league is studying the climate, terrain and soil conditions. It was in this area that it is believed some of the largest redwoods in history existed, but they were all chopped down starting in about 1850.
There are about 1.5 million acres of logged-over groves between San Luis Obispo and Oregon, all of which are growing back. Half of these remaining coast redwood trees are very young, though, with an average trunk diameter of just 8 inches. Nearly 40% of what remains is also bisected by roads, degraded by development, or fragmented by farming and agriculture. And they are closely packed together, according to researchers.
Hodder said these young forests could be an opportunity to restore the natural balance of the ecosystem, a strategy in line with California’s plan to reduce greenhouse gases and the United Nations Intergovernmental Panel on Climate Change, which in 2019 emphasized forest conservation and restoration in addressing climate change.
Hodder envisions a statewide effort by the government, citizens and organizations like the Redwoods League to improve forest conditions, maximize growth and make it so people can no longer tell where the ancient groves of redwood giants end and previously logged stands begin. In the future, perhaps, redwoods could be planted in areas in and outside California best suited for fast growth and maximum carbon storage, Redwoods League biologists said.
“We have such opportunity in the redwood forests to turn the dial and set these forests on a new trajectory and really lead by example on how we can restore our forests,” Hodder said about the findings, which cap 11 years of research by the League’s Redwoods and Climate Change Initiative. “We’ve protected all that we could of the old growth, and we’ve got these islands of big trees that hopefully don’t become museum pieces surrounded by a cycle of clearcutting.”
Scientists are also sequencing the genomes of coast redwood trees and their higherelevation cousins, the giant sequoias. In addition to narrowing down characteristics of the trees to figure out which ones adapt best to changing conditions, like drought and wildfire, the genome study is aimed at figuring out how to use the trees’ hereditary attributes to help the forest ecosystem and creatures that depend on them.
The ultimate plan is to identify where harvested coast redwoods have the highest potential to recover quickly, determine where environmental and climatic conditions, development, industry, pollution and other factors limit growth and figure out how improved forest stewardship can best be deployed.