Nature needs time to heal: how long for Redwoods to recover from fire?
The August 2020 CZU wildfire scorched over 85,000 acres of Big Basin Redwoods State Park. California State Parks redwood ecologist Zane Moore and environmental scientist Joanne Kerbavaz, share their insights into the recovery we can expect.
The August 2020 CZU wildfire transformed Big Basin Redwoods State Park in hours and 86,500 acres in a matter of weeks. Its effects will linger for centuries. The forest is expected to rebound, but when? How long until the forest looks like the place we knew?
To find out, writer Julia Busiek reached out to redwood ecologist Zane Moore and Joanne Kerbavaz, an environmental scientist with California State Parks. “Thinking of those charred trunks,” Busiek writes, “the first thing I wanted to know was: how long until Big Basin’s redwoods are, well, red again?”
“As the tree grows, those black parts will get sloughed off,” Moore said. In 20 years, the trunks will be about half red again. In 40 years, just a few scarred furrows will remain. “Anytime you’re in an old-growth stand, you’ll see scars from past fires.”
Based on data from tree rings and analyzing fire damage in other old growth stands throughout the redwoods’ range, Moore estimates that the CZU fire was a once-in-a-millennium event.
Today just five percent of California’s old growth redwood forests remain. That’s partly why so many trees in Big Basin are named, known, and loved in the first place: Thousand-year-old trees are rare enough that each one felled by fire can seem like an unbearable loss. So it was heartening to spend an hour on the phone with Joanne Kerbavaz, an environmental scientist with California State Parks.
“What I’ve been telling people is that we expect 90 percent of the redwoods to survive,” she said right off the bat. “When you look at how much damage the old-growth trees already had, and they’re still standing after a thousand or two thousand years,” she says.
Last year’s fires were, for most of them, another round of what they experienced before, rather than being something that’s more than they can withstand.
— Joanne Kerbavaz, Environmental Scientist
And when it comes to fire, redwoods can withstand a lot. Their thick, spongy bark insulates the wood, and even their eponymous hue is an adaptation to fire, the result of tannins in their bark. When the bark burns, Moore says, the tannins char quickly, but resist combustion—basically forming a shield that prevents the fire from burning into the tree’s more fragile interior.
If Big Basin’s recovery roughly follows the trajectory scientists have observed following other redwood burns, in the years to come, “The forest will recover from the ground up,” Moore says. In two to five years, he estimates the fire’s remnants on the forest floor will be all but gone. Sparse as last winter’s rains were, they were enough to coax a vibrant bloom of wildflowers and sorrel by spring.
Kerbavaz, meanwhile, spotted banana slugs and salamanders in June, and told me about the educational native plant garden in front of headquarters: “That garden came roaring back this spring,” she said. “Even though the building next door burned with sufficient intensity to melt glass and crack the stones in the chimney, every plant came back next to its little label.”
Caveats, complexities, and climate change notwithstanding, the answer to the question of “How long will it be until Big Basin looks the way I remember” depends almost as much on who’s asking, and what they remember about the park before it burned.