When a giant sequoia in San Francisco’s Garfield Park snapped in two in February, its carcass destroyed several cars and took down a telephone pole. But when a tree falls, other elements of loss are harder to quantify—shelter, shade, a sweet spot to read.
The tree—one of only four sequoias in the city—had likely been around for almost 150 years. But it probably should not have been planted here to begin with, just as many other non-native trees are planted across the city in habitats where they don’t belong.
Roaming around San Francisco these days feels like surveying a battlefield, with trees as the fallen soldiers. Everywhere you look, a mighty giant lies on its side, another victim of an onslaught of stormy weather that has brought more than 12 atmospheric rivers, multiple bomb cyclones, and nearly 80 mph winds to the region. Perhaps as many as 700 trees fell or were broken during Tuesday’s storm alone, and a community-generated fallen tree map lists nearly 1,000 examples.
Falling branches have resulted in multiple fatalities. Historic landmarks have been destroyed, cars totaled and houses smashed. The downed trees are not only a loss for the landscape but also for climate resiliency, since trees are natural carbon sinks.
When the rain finally stops and the debris is cleared, a question will remain: Could we have done better?
The Incredible Shrinking Tree Canopy
Even before the havoc these recent storms wrought, San Francisco already had one of the sparsest tree canopies of any major U.S. city—and it’s shrinking. Trees have not been planted to keep up with the rate of the removal, leading to a continuous decline of greenery. It means we are tens of thousands of trees off of the city’s Urban Forest Plan, which calls for 155,000 street trees by 2034.
The Department of Public Works assumes an annual 4% street tree mortality rate—as stated in the 2021 performance audit of the StreetTreeSF program—which means we would need to plant approximately 5,000 trees every year just to keep up with the rate of removal. But in 2022, the city planted only 2,632, according to a 2022 Annual Urban Forest Report.
No fewer than 22—count ’em, 22—jurisdictions are responsible for contributing to the urban canopy of San Francisco, including the Department of Public Works, SF Recreation and Parks, CalTrans, MUNI, Presidio Trust, SF Public Utilities Commission and many others.
The vast and complex oversight network creates confusion and makes it difficult to count and care for trees. The city may know that a certain acacia is planted on a particular block in, say, the Haight, but in terms of jurisdiction, that tree might as well be planted in no man’s land.
“San Francisco is pretty dysfunctional regarding its tree management,” said Joshua Klipp, an urban forestry advocate and 12-year volunteer with Friends of the Urban Forest. “Because it's just so fragmented.”
Now the city is set to lose even more trees in yet another round of storms—all while not having met its benchmarks for tree planting and adequate maintenance of the trees we still have.
“It's really important that we keep planting, and planting in the neighborhoods in the southeast or in the west, in the Avenues, that have the fewest amounts of trees per block,” said Chris Buck, urban forester with San Francisco’s Department of Public Works. “Because it really becomes an equity issue and a climate issue.”
The Department of the Environment created a Climate Action Plan in 2021 in order to respond to the city’s 2019 declaration of a climate crisis. A key part of that plan is planting trees—some 30,000 by 2024—which is a simple and straightforward way to address the messy complexity of climate change.
The Department of the Environment has not received any funding to plant trees, however, and Prop E, which was passed by voters in 2016, covers tree maintenance and removal but not tree planting.
“Plans are great, but plans are nothing if you don’t put money behind them,” Klipp said. “And what's fascinating about trees is that it is literally the cheapest, most effective investment you can make for the environment.”
But according to Scott Wheeler, manager of The Urban Arborist, it’s very expensive to plant a new street tree—some $1,500 a year, not including watering costs.
Nevertheless, the massive amount of trees lost across the city points even more to the importance of tree planting. The situation has become so dire that it prompted Klipp to draft a resolution for a moratorium on tree removal, which he is presenting to the Urban Forestry Council on Friday.
“We're failing our urban forest plan. We're failing our climate action plan. We're not putting money into this, and we're losing trees by the thousands,” Klipp said.
Part of the reason the recent storms have been so deadly for trees is because of what came before. Trees planted in soil long parched by drought do not hold up when suddenly drenched by repeated torrential downpours.
“With this continuous rain into ground that’s already been saturated, the trees’ roots lose their grip,” said Joe McBride, professor emeritus of landscape architecture and environmental planning at the University of California, Berkeley. “They have nothing to hold onto.”
The near-record wind velocity doesn’t help, nor does the lack of growing space. Planted in very narrow sidewalk strips of concrete, trees don’t have the opportunity to build the kind of root systems they need to stand strong, McBride said.
According to Wheeler, another reason we could be seeing so many tree failures is that they were not planted correctly in the first place.
“Trees are like children. The better a foundation you start them off with, the less headaches they'll give you down the road,” Wheeler said.
Deferred maintenance can also play a role, as this leads to poor tree structure, which in turn makes trees even more vulnerable in storms. Decades of privately managed pruning left trees top-heavy and more vulnerable to wind.
There are also certain species of trees that tend to be more at risk of falling: the black acacia, the Monterey cypress, the Monterey pine and the blue gum eucalyptus chief among them—all of which are commonly found throughout the city. Other widely planted non-native trees hold up well, however.
“An example of a tree that we have most of in the city is the London plane tree,” said Buck. “Yet we have very few failures reported from that species.”
The London plane’s resiliency makes it one of the most commonly planted trees in cities across the world, according to Buck, as it tolerates a lot of urban challenges—we have nearly 9,000 London plane trees, essentially the European version of a sycamore, planted throughout the city, including in Civic Center Plaza opposite City Hall.
Yet given the intensity of the storms this winter, it may be unfair to blame fallen trees on anything other than the wrath of Mother Nature.
“These storms are not a good benchmark for anything, frankly, because they are so extreme,” said Igor Lacan, urban forestry advisor at the University of California Cooperative Extension. Lacan served on SF’s Urban Forestry Council and contributed to Prop E but made clear his comments were not on behalf of the city. “Once you get up to 70 mile per hour wind, it gets very difficult to say, ‘This tree could have performed better or worse.’”
Prop E: Saving Grace or Band-Aid?
For San Francisco’s urban forest, 2016’s Proposition E was a game-changer. Now known as StreetTreeSF, the measure secured $19 million in funding for three key areas: street tree pruning, tree removal and sidewalk repairs.
“It’s an amazing accomplishment,” Lacan said. “So many cities don’t have this kind of funding.”
According to Buck, the tree carnage across the city would be even worse had Prop E not been in effect. Yet a performance audit of StreetTreeSF prepared for the Board of Supervisors makes it clear that StreetTreeSFis not keeping up with its goals.
The 2021 assessment concluded that only 45% of the city’s highest priority trees had been pruned by November 2020.
The report also detailed that key staff positions remained vacant—some for the entire three years the program had been in existence—which complicated the creation of an arborist pipeline to manage the urban canopy.
In theory, the city should prune trees every three to five years. In reality, StreetTreeSF has become a“worst-first” program. Its maintenance cycle has stretched closer to seven years, according to Wheeler.
“It’s a whole different tree at that point,” he said.
The $19 million annual budget runs out every July. Much of it doesn’t even go to maintenance, but to sidewalk repair—and none of it covers tree planting.
Given that SF already has one of the smallest urban tree canopies of any U.S. city, can we maintain our "green" reputation after yet another round of storms in which we could lose hundreds more trees? After all we’ve already endured, can we withstand more carnage?
Correction: A previous version of this story inaccurately estimated the potential percentage loss of San Francisco trees.
Julie Zigoris can be reached at [email protected]
Liz Lindqwister can be reached at [email protected]