Prescribed burns at Henry Cowell Redwoods State Park were carefully planned, will improve health of old-growth forest

On a sunny, clear day last week – a respite between two soggy atmospheric rivers  – workers at Henry Cowell Redwoods State Park took advantage of the perfect conditions and ignited “good fires” in the 40-acre old-growth redwood grove in the Santa Cruz Mountains. The prescribed fires were intended to make the woods healthier and reduce the danger of unwanted fires later. 

Crackling and popping fire interrupted the quiet. The green landscape was ablaze with patches of bright orange flames, flickering and sparking in the shade of giant trees, some over 1,500 years old. 

A team of about a dozen park staff trained in prescribed burning techniques worked quietly and efficiently as they ignited and tended to 82 brush piles throughout the redwood loop. 

The prescribed pile burns “not only reduce the risk of catastrophic fire, but also maintain the structure of the old-growth forest,” said Dylan McManus, California State Parks interpreter, who coordinated the volunteer-driven prescribed burning project. 

These fires are a safe way to  reintroduce fire into a fire-adapted ecosystem. California’s redwood forests evolved with fire, both naturally occurring and through the practices of Indigenous peoples in the area for thousands of years.

Fire has been largely absent from this Henry Cowell redwood grove for the past century and a half, with the most recent documented naturally occurring fire in 1867. Although annual prescribed burns have been conducted in the park over the past decade, the location of those burns has been in the sand chaparral ecosystem.

“Without allowing fire to move across the landscape as it would do naturally, there’s just a huge accumulation of fuels, particularly after these significant storms in the past two years,” McManus said. “Old-growth forests have evolved with fire for many, many, many years. So we simply can’t take it away. There has to be some form of fire, and in this day and age, it means in the safest way possible.”

Pile burning is safe and straightforward. It produces comparatively little smoke. When the piles are constructed and placed properly, and burned under the right conditions, there is very little chance of fire spreading beyond the piles.

Pile burning is a labor-intensive effort. Dozens of volunteers worked over the previous year carefully constructing each brush pile. The volunteers then placed larger logs on the exterior of the piles, creating an “armor” that contains the fire while ensuring it burns hotter and completely consumes the material while reducing smoke and the chances it will spread. 

“One of the reasons we burned the day we did was because they are very well-built piles. We could burn when everything else was sopping wet and the piles would still light,” said Tim Hyland, State Parks natural resource program manager and “burn boss” for the recent fire operation.

Donald May, a park docent, has been helping to build the brush piles. He began volunteering for the state park eight years ago, as a way to cope with his wife’s death. “If you come up on hard times,” he said, “if you do something that pleases yourself in the midst of that … and [you] explore yourself within it, then that certainly helps the grief pass away.” 

On the day of the burn, Feb. 5, May watched the team’s hard work pay off.

“The diagram of the flame coming up from the top of the pile mirrors the shape of the wood that is put on top of the pile. If you look at it carefully, you’ll see no fire extends outside the shape of the pile,” he said. “That keeps it safe. It’s professionally built and professionally burned, and it makes it look right.”

Another benefit of the burn was “educating people about the role of fire and kind of normalizing the use of fire as a tool to manage landscapes,” said Hyland. “Being able to do this right there in the old-growth loop is a really important thing.” The area remained open during the burn. Park staff are hoping to schedule future burns on weekends to give people more opportunities to come and observe the process. 

The use of fire as a land management practice is not new. “We’re still very much learning from our tribal partners,” said McManus. “This has been part of their ancestral practice for thousands of years.” 

According to pamphlets from the Central Coast Prescribed Burn Association, “prescribed fire offers a range of benefits for ecosystems, wildlife, communities and cultural practices. It is a valuable tool for maintaining healthy landscapes and reducing the risk of catastrophic wildfires.”

“One of our guiding principles for land management is to reintroduce natural processes that systems evolved with, and fire is one of those natural processes,” said Hyland. “The best information that we have is that the mean fire return interval was somewhere between seven and 12 years in redwoods in the Santa Cruz Mountains.” 

While there is good data on broadcast burning in the redwood forest, less is known about the impacts of smaller scale intentional fire burning. “It does remove woody debris and lignin, the things that fungus feed on. It can potentially reduce fungal load,” Hyland said. “But after the CZU lightning fire in 2020, you had the appearance of fire-following fungi that nobody had ever seen in this county. So you’re stimulating and somehow impacting the fungal community.”

“The interactions in these systems are so complex that we can’t, you know, say I’m gonna do this to make that happen,” he added. “All we can really do is say, well, we know that in the past these systems burned. We will go ahead and we will try and replicate that with the intent that all of those things that rely on those processes will then follow.”

“Potassium, nitrogen, carbon – all that material goes back into the ground instead of just chipping it and loading it in a truck and hauling it away where you lose everything,” said Bob Woodruff, another docent who leads a weekly 10-person volunteer crew in the park. He likes to think of their work as “rehabbing the forest.” He says redwood sorrel and wild ginger, which had been buried beneath the debris buildup, have been able to resprout, providing fresh forage material for deer. Redwood seedlings are starting to reclaim their territory from bay laurel trees.

McManus has also noted subtle changes to the health and structure of the forest: “We see a few different species of ferns that are resprouting the following growing season after our prescribed fire, out of the ashes. It is very, very cool.” He has observed bracken fern, wood fern and sword fern. 

When the park system extends a similar program to the old-growth loop at Big Basin Redwoods State Park, staff plan to collect vegetation and fuels data from before the burn so that they can clearly show afterward the impact that this work is having.

The recent burn was only the third prescribed burn in the old-growth grove since they began in 2023. To date, 226 brush piles have been burned. And there is still more work to do. Volunteers have already built six new piles. The park will continue prescribed burning annually until all 40 acres in the old-growth grove has been addressed. 

“It’s like playing a symphony in an orchestra. The first time you do it, there are lots of halts and starts and stops just to get the music and the feeling and all of it,” May said. “The first rehearsal is yet a further refinement of it. The third time, you bring people together to play in the symphony, you are up and ready to give it the best shot. That’s exactly what happened regarding the fire that we built. It was symphonic in nature.”

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