Destruction of Chaparral at Big Basin Redwoods State Park
California State Parks Fails to Understand Natural Succession
CEANOTHUS TEACHES US ABOUT FIRE HISTORY IN COAST REDWOOD FORESTS
By Steve Singer, M.S., Forest Biologist
Ceanothus is usually thought of as a chaparral plant, but one species of Ceanothus occurs as an understory shrub in our coast redwood forests – Blueblossm Ceanothus (Ceanothus thyrsiflorus).
The 2020 CZU fire that burned Big Basin Redwoods State Park, destroying all structures and burning away all the branches of mature and old-growth coast redwoods, was followed by something never seen before in the park since its founding in 1904. It was the germination and growth of many thousand Ceanothus thyrsiflorus plants. They now form a dense green “wall," 15 feet high, beneath the scorched redwood trunks.
Since coast redwoods, unlike Sierra redwoods, can sprout new branches from the trunk and new stems from the root collar, they were not killed by the fire. However, the normal forest floor vegetation of ferns, redwood sorrel, and other herbaceous plants has been completely replaced by a sea of Ceanothus.
I had been interested in the natural history of the park since the 1970s when I was a park ranger there. My scientific curiosity was tweaked by the Ceanothus irruption, and I quickly learned that the life history of Ceanothus thyrsiflorus was largely unknown. So, I did a deep dive into the available scientific literature and picked the brains of Ceanothus experts.
What I discovered was that Ceanothus thyrsiflorus and its coast redwoods associates
The 2020 CZU fire that burned Big Basin Redwoods State Park, destroying all structures and burning away all the branches of mature and old-growth coast redwoods, was followed by something never seen before in the park since its founding in 1904. It was the germination and growth of many thousand Ceanothus thyrsiflorus plants. They now form a dense green “wall," 15 feet high, beneath the scorched redwood trunks.
Since coast redwoods, unlike Sierra redwoods, can sprout new branches from the trunk and new stems from the root collar, they were not killed by the fire. However, the normal forest floor vegetation of ferns, redwood sorrel, and other herbaceous plants has been completely replaced by a sea of Ceanothus.
I had been interested in the natural history of the park since the 1970s when I was a park ranger there. My scientific curiosity was tweaked by the Ceanothus irruption, and I quickly learned that the life history of Ceanothus thyrsiflorus was largely unknown. So, I did a deep dive into the available scientific literature and picked the brains of Ceanothus experts.
What I discovered was that Ceanothus thyrsiflorus and its coast redwoods associates
occur in a plant community tightly restricted by millions of years of evolution to a long-interval fire regime. This is contrary to the prevailing belief that coast redwood forests, under natural conditions, would normally experience smaller fires every 10 years or so. Furthermore, it assumes that the cessation of these fires due to the lack of Native American burning and modern day fire suppression efforts had led to a build-up of ground fuels that caused the 2020 CZU megafire in Big Basin. The massive irruption of Ceanothus in Big Basin after the fire has thoroughly discredited this theory.
One would think that most fire ecologists and forestry professors would welcome the new information, but they have not. Instead they seem to be locked into the old theory – perhaps because it gives them an excuse for entering and manipulating old-growth coast redwood forests, something that previously had been considered off limits.
It is now clear that the 2020 CZU fire was not caused by the build-up of ground fuels. Therefore, prescribed burns and thinning, as currently being undertaken in state parks, is unnecessary and is actually damaging to the overall forest health. For the full details, please read the full article here: “Mass Irruption of Ceanothus After the 2020 CZU Fire Provides a Lesson for Redwood Forest Management.”
One would think that most fire ecologists and forestry professors would welcome the new information, but they have not. Instead they seem to be locked into the old theory – perhaps because it gives them an excuse for entering and manipulating old-growth coast redwood forests, something that previously had been considered off limits.
It is now clear that the 2020 CZU fire was not caused by the build-up of ground fuels. Therefore, prescribed burns and thinning, as currently being undertaken in state parks, is unnecessary and is actually damaging to the overall forest health. For the full details, please read the full article here: “Mass Irruption of Ceanothus After the 2020 CZU Fire Provides a Lesson for Redwood Forest Management.”
Additional Information
Additional information about the natural environment of the Santa Cruz Mountains, please visit the The Santa Cruz Mountains Bioregional Council (SCMBC).
Our letter opposing the massive alteration of Big Basin Redwoods State Park is available here.
A portion of our letter:
"Dense, impenetrable stands of native shrubs are the natural condition for shrublands like chaparral and sage scrub. Understory shrubbery and dead wood in forests create valuable habitat for native animals – this is especially true with fire return intervals of a century or more like those of the redwood-Doug fir forests along the coastal zone.
Contrary to what is continually reported in the news media, post-fire shrubland and forest environments are rich, vibrant ecosystems. They are not destroyed landscapes. The problem we face is impatience. Yes, climate change is increasing the flammability of California. But the answer is not to clear the natural environment – the solution favored by Cal Fire (and now Cal Parks)."
Photo Above: The beautiful blossoms of Ceanothus thyrsiflorus.
Photo Right: 12-foot range pole in front of a large Ceanothus thyrsiflorus, at the former Upper Opal Creek Picnic Area in the park. Taken 4-18-25.
