Arborists have been busy in Berkeley.
“I don’t recall a year being this bad,” said Kerry Bliss, a certified arborist who has worked in the Bay Area since 1995. “It’s a combination of the over-saturation and the wind that has just been difficult. The trees are so much bigger than they were 20, 30 or 50 years ago: they’ve doubled in size, and then the storms doubled in size.”
Fierce winds from over a dozen storms took their toll on trees rooted in sodden soils, with a late March bomb cyclone, in which gusts topped 60 mph, dealing the most damage.
Falling redwoods — two of them — crushed a house near Ohlone Park. And a tree that fell near the Rose Garden trapped people in a pickup truck for hours. Less dramatic but nearly as heavy a lift for the arborists who mop up after storms were the trees that fell by the dozen on front yards, back lawns, fences and flower gardens.
“The storms of this winter were much more severe than usual, especially the one on March 21,” wrote Berkeley parks director Scott Ferris in an email. Clean-up is ongoing, he said, and will continue through May.
There’s no one tracking all the trees that fall in Berkeley, but Ferris estimated that this year’s storms brought down 85 trees on city property, more than a third falling at the Berkeley waterfront. And, he said, more trees fell during the March 21 storm than in “any single storm that we’ve ever had.”
From the beginning of December through the end of April, Berkeley received more than 300 calls related to broken branches and trees — more than in any winter since 2015-16. The totals are likely an undercount as many, particularly those on private property, go unreported.
The extended winter storm season, Ferris said, has left city staff with a backlog of tree removal work typically done by the end of spring. Save for an Arbor Day event in San Pablo Park in which 20 trees were planted, the city hasn’t been able to plant many trees since the start of winter because of the weather and the amount of downed trees to respond to.
“The big impact that this winter has had on our staff is that we spend most of the time cleaning up as opposed to planting,” Ferris said. “We’ve got some catching up to do…but with the extended winter, that means the planting season was extended.”
Trees with long history damaged or lost this winter
One of the trees at the marina that didn’t survive the March 21 storm was a “magnificent” 80-foot Guadalupe Cypress planted in the ’80s in the Native plant area of Cesar Chavez Park, according Martin Nicolaus, director of the Chavez Park Conservancy.
“Wind blasts apparently came from the southwest, where the giant had little shielding. It might well have survived this also had the ground been firm,” Nicolaus wrote in a blog post. “But the soil was waterlogged and soft, and the force of the wind on the foliage created an overpowering leverage that ripped the roots out of the ground.”
At the UC Botanical Garden, the storm sheared off the trunk of a treasured, 150-year-old coast redwood to the point that it is beyond saving, in the process damaging several other plants including a centenarian California buckeye. Finding an arborist willing to take on the job of removing the tree, however, has been a challenge, according to Andrew Doran, the director of collections at the garden — two companies have declined bidding on the tricky project so far.
Over on the UC Berkeley campus, on which more than 13,000 trees grow, the March 21 storm brought down roughly 14 trees — mostly eucalyptus. Typically, the campus sees between three and five tree falls per year, UC Berkeley Director of Operations Felix Deleon wrote in an email. This winter, 20 fell.
Fifteen years after protesters took up residence in trees outside Memorial Stadium as part of unsuccessful attempt to protect them from a campus development project, two of the grove’s remaining oaks were toppled in the March 21 storm.
UC Berkeley spokesperson Dan Mogulof said university officials don’t know if either of the destroyed trees were among the handful that predated the stadium’s construction, or if they had been planted as part of a landscaping project in the 1920s.
The protests against UC Berkeley’s plan to clear dozens of trees in order to build a training facility now known as the Simpson Center for Student-Athlete High Performance drew national attention in the mid-2000s, less than a decade after Julia Butterfly Hill’s famed tree-sit during the “Timber Wars” in Humboldt County.
As many as a dozen people lived in treehouses and platforms suspended in the grove’s coast live oaks and redwoods during the occupation that began in late 2006, the San Francisco Chronicle reported, while neighborhood and environmental groups, joined by the city of Berkeley, sued the university to block the project. A judge ruled in the university’s favor in July 2008, according to the Chronicle, and the tree sitters peacefully surrendered two months later, allowing the project to begin.
Trim the tree, deflate the sail
Bliss, the local arborist, said he’s personally removed around 50 felled trees in Berkeley this year.
Most have been Monterey pines, redwoods, eucalyptuses and coast live oaks in the Berkeley Hills. These species aren’t especially prone to falling — they’re just very common, according to Bliss. Consecutive years of drought may have weakened roots and increased the chances of a collapse.
“People tend to think of roots being kind of like a carrot, but in reality, for almost all the trees in the area, 90% of the roots are in the top 3 feet of soil,” said certified arborist Joe Lamb, co-owner of the tree work company Brende and Lamb. “Imagine a wine glass with a base two to three times larger than the globe at the top.”
With proper upkeep, most trees in Berkeley are stable, Lamb said.
Bliss, likewise, said most of the trees he’s removed have vigorous canopies and seem healthy. But repeated rains meant trees took on a lot of moisture, not just through their roots, but also on the surface of their leaves and needles. It added an “immense” amount of weight to the trees.
“A well-thinned tree limits the sail surface, by reducing the number of leaves and by making spaces between branches so wind moves through the canopy instead of just against it. Imagine a sailing boat with fewer sails per mast.” — arborist Joe Lamb
Plus, trees in the hills tend to grow taller to compete for limited sunlight. High winds turn those giant trees into dangerous pendulums that dramatically swing back and forth.
“When you add that to the equation, it’s just a recipe for disaster,” Bliss said.
Proper pruning can help. There’s “no such thing as a maintenance-free urban forest,” Lamb said. Leaves act like little sails; by trembling in the wind, they reduce the wind load on branches. It’s a delicate balance: If winds are too strong and the tree too heavy, the tree may succumb to the wind’s pressure.
“A well-thinned tree limits the sail surface, by reducing the number of leaves and by making spaces between branches so wind moves through the canopy instead of just against it. Imagine a sailing boat with fewer sails per mast,” Lamb wrote in an email. “When drought reduces the anchoring power of the roots, and when the soil is saturated, and when the winds are ferocious, then only a well pruned tree can weather the storm.”
Climate change is intensifying droughts and making dangerous winter storms more likely, and climate scientists have said this season’s storms could be only a taste of the megafloods to come.
Lamb said he’s seeing increasingly extreme damage to usually hardy trees that he’s gotten to know over the decades he’s worked in Berkeley. In March, he was hired to prune an established eucalyptus tree in Berkeley.
Upon close examination, he learned that the tree was unsalvageable and would need to be removed — there had been a major crack in the trunk invisible from the ground. Cracks in trunks aren’t unusual, but the size of this one was, Lamb said.
“The problem that I’m facing as an arborist [is that] the weather events that we’re having now that are supercharged are different than what I’ve experienced during that 40 years,” Lamb said. “So you have to suddenly be a lot more cautious with pruning and tree care recommendations.”
City Hall reporter Nico Savidge contributed reporting to this story.
This story was updated after publication.
