Trees of Life

San Francisco will soon assume responsibility for the city's nearly 125,000 street trees. It couldn't come at a more crucial time.

On a fog-filled, June-gloom day, 20 or so people mill around on a Cole Valley sidewalk. They seem like your normal Saturday-morning crowd, indulging in that oh-so-San-Francisco tradition of waiting in a long line for eggs. But a closer inspection reveals name tags, work gloves, hand spades, and an anxious anticipation that even the most overpriced omelettes won’t ease. These are volunteers for Friends of the Urban Forest, and they’re about to attempt what Frederick Law Olmsted, the designer of New York’s Central Park, famously said would “not be wise nor safe to undertake” in San Francisco.

They are about to plant trees.

Maybe Olmsted would have been more supportive of trees in San Francisco if Proposition E had been around. Passed in November 2016, Prop. E transferred the responsibility of San Francisco’s nearly 125,000 trees from local residents back to the city. San Francisco had unburdened its tree duty onto city dwellers back in 2011, when it was facing a $380 million general fund deficit. But the decision by Big Brother to dump Big Trees on San Franciscans did not work out, to say the least. Property owners’ resentment boiled over in 2015 for having to spend upwards of $1,000 pruning each tree on their property — ones the city had originally planted. Things got so bad that it caught the attention of then-Supervisor Scott Wiener, who noticed that low-income residents had been hiring inept, cheaper arborists who left trees “butchered.”

Seventy-eight percent of San Francisco voters supported Prop. E, which goes into effect July 1, meaning that if a tree on the owner’s portion of the sidewalk falls before that date, he or she is most likely liable for cleanup and any damage. After July 1, however, the city foots the bill.

Prop. E covers the maintenance of the current forest but not the planting of new trees, so fundraisers by organizations like FUF, a nonprofit started in 1981 by concerned citizens in Noe Valley who thought San Francisco was not planting enough trees, are necessary to sustain the urban forest. Despite the scientific evidence that trees increase our mental, physical, and spiritual health, activists still have to fight for the dollars to sustain them.  

On this particular day, Margaret Tough is hosting the meeting spot for the tree-planting foray in front of her Cole Valley home. Although the majority of the volunteers will spread like pollen throughout Cole Valley and the Sunset District to plant 22 trees, Tough is staying put on her front sidewalk for good reason: A skinny, thin-leaved juvenile Podocarpus gracillor, or fern pine, which she purchased from FUF on a sliding scale, will be planted on her front sidewalk. The fern pine replaces a tree that fell down during a windstorm three years ago, while Tough was on safari in Africa.

Tough’s tree will be one more soldier in the local fight against global warming. According to city data, aside from increasing home values and reducing the effects of asthma among children, San Francisco’s urban forest also filters more than 19 million pounds of carbon out of the atmosphere each year. Like global warming, the global tree population is a concern for us all, as trees are a clear indicator of how the world is connected. For example, scientists have long wondered where trees in the Sierra Nevada got their life-giving supply of phosphorus, which comes in limited pockets in those mountains. This past March, a team from UC Riverside discovered a jetstream was carrying the essential element all the way from the Gobi Desert to California. Tough’s tree is closer to Africa than she realizes.

Prop. E also sets aside $19 million per year from the city’s General Fund for the pruning, removal, and general maintenance of San Francisco’s urban forest. But even that kind of cash can’t guarantee the future of urban trees in San Francisco. The relationship between cities and trees in the United States has not always been an easy one. In a city as dense as San Francisco, it’s a struggle to make room for an occupant that provides oxygen and shade, but that also comes with roots that can destroy cement, water lines, and (gasp!) our DSL — not to mention long limbs that can grip and rip power lines. Considering our twisted relationship with trees, it’s no wonder they need a hug.

And when urban trees are introduced willy-nilly or treated like inert objects to post in any available square in the city sidewalk, they grow into big problems later.

California Buckeye at 2694 McAllister St. (Courtesy of Michael Sullivan)

The challenges city trees in the United States face go all the way back to the country’s founding. In her best-selling 2016 book, Urban Forests: A Natural History of Trees and People in the American Cityscape, author Jill Jonnes rewrites our country’s history through the planting, pruning, and cutting of trees.

George Washington was first among presidents not only in terms of order but in his love for trees, Jonnes writes, battling a well-established Puritan view that trees were really fences, tables, and roofs just waiting to meet the right axeman. Washington would spend “countless happy hours … scouring his own woods for the perfect maple or dogwood” for his beloved Mount Vernon. Teddy Roosevelt renewed the need for an urban forest in 1907 by proclaiming,“To exist as a nation, to prosper as a state, and to live as a people, we must have trees.” Legend also has it that Roosevelt, predating hipster trends by a century, had his family motto — Qui plantavit curabit, or “He who has planted will preserve” — tattooed somewhere on his body.

Although these presidents fought against a civic and religious mentality of trees as simply lumber, the greatest modern threat to trees, urban or otherwise, remains disease. In San Francisco, pine pitch canker, which looks as bad as it sounds, has brutally attacked the Monterey Pines, creating resin-oozing cankers that attract four spined engraver beetles and twig beetles, which burrow mercilessly through the vulnerable wood. According to the U.S. Forest Service, more than 100 million drought-stressed and beetle-damaged trees have died in California since 2010. Most are still standing, a towering zombie horde ready to tumble on unsuspecting hikers or crash through car windshields. And without a concentrated international effort to fight climate change, the rising temperatures will allow more and more kinds of invasive insects to live longer and travel farther, a doomsday scenario for trees everywhere.

“We’ve been operating through triage the last 10 years,” Rachel Gordon, Director of Policy and Communications for San Francisco’s Department of Public Works tells SF Weekly. “We’ve been on a 10- to 12-year pruning cycle of our urban forest, and we need to be on a three- to five-year cycle.”

To help wage this campaign, Prop. E classifies the 125,000 urban trees into three groups, or “priorities.” Priority one addresses those trees in San Francisco that are in such bad shape that they may need to be removed lest they fall.

“About four years ago, we began a tree-relinquish program,” Gordon says. “We just did not have money to take care of trees. Not surprisingly, people were not happy. Under Public Works code, we’re able to do that. We did that reluctantly.”

On the political front, according to Gordon, then-supervisors Scott Wiener and John Avalos worked to find a sustainable funding source that could be drawn from the General Fund and set aside every year. And when drought-stricken trees started to crash down in San Francisco from high winds and the start of historic rains, Prop. E seemed well-timed.

“A big ficus tree came down on Dolores [Street] and hit a stair railing on a house,” Gordon says. “Public Works got the 40-foot tree out of there in a couple of hours. When a tree comes down on public property and hits a car or crosses a sidewalk, we’re the first responders.”

Popularity for Prop. E also rose when it became clear that the city would be responsible for not just taking care of the trees, but taking care of the sidewalks their roots tend to bust up.

“Folks know that repairing sidewalks is not always cheap to do,” Gordon says. “People can be injured and get sued. After July 1, sidewalks will be assumed by the city.”

What really enhanced the city’s ability to take care of the urban forest, Gordon says, was the City Wide Street Census and resulting Urban Forest Map. Carla Short, Superintendent of the Bureau of Urban Forestry of San Francisco Public Works, agrees.

“The City Wide Street Census changed everything,” Short says. “We now know how many trees we have: 20,000 more than we estimated, in fact.”

For anyone with any curiosity about the trees in San Francisco, the Urban Forest Map is just about the coolest thing ever, allowing people to geek out on data. You’ll learn that the most common tree in San Francisco, with a population of 8,620, is the London plane tree (Platanus acerifolia), a hybrid sycamore. One of the world’s great street trees, it lines the Champs Élysées in Paris, it’s found in a van Gogh painting, and it has been planted in cities from Australia to Alaska. You’ll also be able to learn about specific trees, like that Indian laurel fig on Cyril Magnin Street you pass on your way home from the Powell Street BART station. The 17-inch trunk diameter of that Ficus retusa filters 1,531.3 gallons of stormwater per year and has sequestered 1,279.9 pounds of carbon dioxide to date.

“Trees always compete with other necessities in the budget,” Gordon says. “Right now, we have a good economy. But in lean times, if trees have to compete with fire stations or homeless services, trees don’t have the constituency and support of these other needs. When times are lean, trees will lose out.”

Gordon says the biggest challenge to Prop. E was the lag-time between passage and implementation. “The funds aren’t available until July, and even now setting up the program will take some time,” she says.

Short agrees. “People should know they can’t just call the city on July 2 and get a truck out there the next day to prune their trees,” Short says. “We have to go by priority. It should take three years to set up a clear maintenance schedule.”

There’s no funding for tree-planting in Prop. E because there’s so much deferred maintenance, but the money should be generated over time. Short uses the analogy of a deferred dental visit. Right now, there’s a lot of extra cleaning, and perhaps teeth-pulling, to take care of, which means lots of labor hours and expense. But once the maintenance is set, the remaining urban forest should be less expensive to maintain, which would free up money to plant trees. “Over the next 10 to 15 years, we would like to add 30-60,000 street trees,” Short says. A lot of those new trees will depend on how much San Franciscans are willing to share their space — and their money — to support an urban forest.

The argument that San Francisco’s sandy soil and salty fog compromise its suitability for street trees, or that we’ll never be as leafy as, say, New York, doesn’t deter Short. “San Francisco wasn’t all sand dunes,” she says. “And we just don’t live in what San Francisco was. There weren’t big buildings and concrete sidewalks back then, either.”

And New York City residents have their own tree issues. In “Sidewalk Saga on Staten Island,” as reported by New York’s PIX11 TV on June 7, Vincent DeCandia and Dawn Galante on Doane Avenue in Staten Island were among several residents slapped with city violations for busted-up cement near trees in front of their house.

“It feels like the mayor has his hand in our pockets again,” DeCandia said in the program.

Asked what tree presents the biggest problem for San Francisco’s urban forest, both Gordon and Short finger the ficus. It’s the posterchild of urban-forest problems for San Francisco, although Short defends its good qualities, in a motherly way.

“Hyde Street is lined with them,” she says. “They are workhorses who take a tremendous amount of abuse and keep growing, which is key for urban trees. It has a dense canopy, though, and a natural inclination to drop large limbs when they get heavy.”

For the record, the city no longer plants ficuses. Like city people versus country people, some trees are just better suited for less urban environments. “A ficus could do better in a less dense city than San Francisco,” Short says.

Another local troublemaker is the black acacia, which can self-seed so quickly and easily that it takes over. “No tree can invade in a sidewalk situation, but the acacia can take over a whole hillside,” Short says.

The acacia is an example of how one community’s tree problem could be another’s solution. According to the United Nations, the expanding Sahara could cover two-thirds of Africa’s arable land by 2025, diminishing already limited farmland and creating even more famine. The solution? The Great Green Wall of Africa, an internationally-funded project begun in 2005 to plant an immense buffer of trees — mostly acacia — nine miles wide and 4,750 miles long to contain the mighty Sahara.

The most controversial tree in the Bay Area has to be the blue gum eucalyptus, a tree adored by some for its wind-braking power but villainized by those who see it as a foreign invader crowding out native plants. The fight has raged for years, with each side blasting out their arguments so loudly that The Atlantic covered the debate in 2016 and concluded that “the magnificent Tasmanian blue gum is, in some sense, a prisoner of dueling realities.” There’s nothing like the environment to get San Franciscans hot, and it’s important to protect trees from the mad thresher of our political, social, and economic arguments by realizing they help us all. Our urban forest is both healthy and delicate, able to take a certain amount of abuse but also incredibly susceptible at the same time.

According to Short, San Francisco took some cues from urban forest programs in cities like, Milwaukee, Santa Monica, and Philadelphia. Santa Monica’s program became fully funded once it became clear that maintaining a healthy urban forest actually saves the city from the liability of falling trees. Money may not grow on trees, but proper urban forestry measures are proof that trees can grow on money. Short emphasizes that diversity is key to San Francisco’s healthy urban forest. “We have no more than 10 percent of any tree species,” Short says. This diversity is important, because a disease can wipe out a monoculture.

“I went to school in New Haven, Conn., which used to be known as ‘Elm City,’ ” she adds. “Then Dutch Elm disease wiped all the elms out.”

Two phone conversations with tree enthusiast Mike Sullivan are all it takes to see the city through the history of its trees. That’s because Sullivan wrote The Trees of San Francisco, a slim, 160-page read that feels as useful to living in San Francisco as scrolling through Craigslist. “Over the years, the city took care of the big streets like Market, Geary, and California,” Sullivan says. “But where I live in Cole Valley, no street is maintained by the city. It’s all owner-maintained.”

Thumb through The Trees of San Francisco, and you’ll discover how intertwined the histories of people and trees really are. There’s the row of blue gum eucalyptus on Octavia Street planted by Ellen Pleasant, California’s “Mother of Civil Rights;” the beloved wild parrots of the Embarcadero that nest in the open sockets left when Canary Island date palms drop their fronds; the gingko biloba trees, a name that sounds like Jango Fett’s long-lost son but which is actually the oldest known tree species, dating back 250 million years; and the California Buckeye on McAllister whose seeds Native Americans used to damm up streams to catch fish.

Trees lining Lake Street in San Francisco (Photo by Mike Koozmin)

The warning beeps of big trucks moving backward cuts through the din of Market Street’s morning traffic. A row of orange cones forces Friday commuters into one lane and underneath two large Chinese elms whose limbs beg for pruning — at least, from the city’s point of view. A Public Works truck with a lift bucket raises an employee with a chainsaw toward the first tree, while a smaller truck positions its chipper where the lopped off limbs will soon land.

The realities of urban tree maintenance become apparent watching this crew. Jonathan Perrin, a city arborist in charge of the day’s work, requests that the crew remain anonymous.

It’s clear one man is deferred to on the crew, not just because he has the biggest chainsaw but because Perrin estimates he’s been working on trees at least 30 years. He moves in and out of the tree like a sculptor, trying to keep perspective of the whole while working limb by limb.

“He’s cutting away any leaders that are headed down or over the traffic,” Perrin says.“That should help promote the tree to grow up. The idea is to promote a healthy structure within the space the tree can occupy, and to allow as much of a healthy canopy as possible. We try to keep the amount of tree that we prune away to about 15 to 20 percent of the total.”

John Trompeter, who rents an apartment in front of the tree, hears the ruckus and joins the conversation. He’s quick to point out a vacant dirt section in the sidewalk where a tree used to stand. Trompeter says that’s where another Chinese elm just like the one being pruned toppled over last year. “We called and called the city about that tree,” Trompeter says. “But nothing happened until it fell.”

Trompeter points to the elm being worked on and notes how the tree bends downhill, not just because of gravity but because of the wind and fog that barrels down Market Street from breakers to bay. “All the concrete is being pushed up around it, too,” he observes. “I’ve lived in San Francisco for 29 years and I’ve never seen so many trees falling down in the city.”

Perrin hopes Prop. E will address most of Trompeter’s concerns. As his colleague Rachel Gordon noted earlier, Urban Forestry was woefully understaffed and running a band-aid operation for years. “If we got a call from a bus or large truck that there was a low-hanging limb they were hitting, we went out and addressed that,” Perrin says. “But Prop. E will get us back into a healthy cycle of maintaining the trees. Instead of just clearance issues, we will be able to address whole structural issues.”

The whine of chainsaws near trees seems to draw people out, especially those who live in homes that the trees beautify. Another resident, Tyler, comes outside to make sure the city is not removing the entire tree. He’s relieved to discover it’s a prune job, and he leaves after offering this challenge to the Public Works crew: “Barcelona is adding more and more trees. Why can’t San Francisco?”

Besides hoping to plant more trees, Public Works wants to prune as little as possible, hoping the trees can grow within their city confines as naturally as possible. But sometimes there’s no other option. For example, in the case of the second tree being pruned, the need was as clear as the rusty, six-foot metal rod discovered sticking out of a lower limb. When asked how that rod got stuck nearly two feet into a trunk, Perrin said my guess was as good as his.

When an underlying crack was found in a large limb stemming from the metal rod, the decision was made that the whole heavy limb had to go. When the thick, circular slabs of the limb bounced off Market Street one by one and shook the ground under my feet, 20 feet away, it became clear why the city didn’t want the limb — and protruding steel rod — dropping of its own accord.

The tree is left with a sizeable cut, but because elms are tough and fast-growing, Perrin is confident it will recover. Back in the old days, they used to paint over the cuts with black tar, he says, but it turned out the tar retained moisture, slowing the healing process.

Trees know how to recover from these human-inflicted traumas. Remember: They’ve been recovering from our presence ever since we found two sticks to rub together to make fire.

New website documents every tree in San Francisco. (Courtesy of

Bringing Jonnes’ consideration of presidents and their relationships with trees in Urban Forests up to the present day, that longstanding relationship does not end well. After Teddy Roosevelt, several understood the primacy and importance of the relationship. President John F. Kennedy appreciated an English elm he dubbed the “Humility Tree” because senators had to bow their heads if they wanted to pass. President Barack Obama loved the smell of the flowering Magnolia grandiflora that Andrew Jackson had planted back in 1829 to honor his late wife.

But our current president pulled out of a global agreement that, according to the Trust for Public Land, would have been a boon for urban forests.

“The Paris Accords was a meeting of nations, but it also included more than a thousand mayors,” a 2016 report by the Trust read. “That’s because there’s lots to be done on a city level: for starters, planting trees. On top of capturing and storing carbon (like any forest), tree cover in urban areas reduces the heat-island effect, helping protect cities’ most vulnerable residents.”

With Gov. Jerry Brown leading the charge against the scientifically proven threat of climate change, planting a tree feels like the most radical act in the most radical town in the most radical state in the union.

The groups fan out from Tough’s house, leaving one small team of seven to plant the fern pine. The square patch of dirt surrounded by pavement, the classic fish tank for urban trees, is cleared of all rocks “bigger than a fist.” An old, rusty pipe, running right across the space a half-foot down, is deemed to be long dead and not a problem for the tree’s roots. A hole the depth of the black bucket is dug, while a volunteer rolls and smacks the bucket on its side with a hand shovel to release the roots, eerily similar to the smacks administered to a newborn baby to bring life. The root crown on the tree is found — the top, largest root that should remain uncovered to prevent infections — and the group carefully adds and subtracts earth to ensure that that crown will remain above ground when the fern pine is planted. A handsaw is taken to the root bulb, and a veteran volunteer points out how the roots have wound themselves into a tight ball. Three hefty slices frees most of the roots, and a light massage frees the rest. Some rich nursery soil is mixed into the compacted cement soil to ensure that the young tree has good reason to send out new roots. The heaviest side of the tree is positioned west, toward the incoming ocean gusts, to allow the less leafy side some protection and to encourage balanced growth.

Once the tree is correctly positioned, it’s determined that more soil is needed, and Tough zips over to Cole Valley Hardware for two bags of mulch and two of soil. Three wooden stakes are set with a stake pounder, a weight with handles that cup over the top of a stake. It’s strong enough to drive the tall stakes down yet heavy enough to require that anyone nearby wear a hardhat. The smaller nursery stake is pulled away, and the hole that’s left is quickly filled to prevent an easy pathway of unwanted critters to the young, vulnerable roots.

A simple wooden sign is nailed to two posts to identify the plant — and promote Friends of the Urban Forest — and the tree is lightly tethered with straps, tight enough to prevent it from falling down, but not too tight to prevent the roots from growing and the tree from standing on its own, like the best part of a helicopter parent’s intentions. Tough kicked in an extra $20 for a 40-gallon watering bag, which she needs to fill once a week for three years to establish the tree.

When it’s all done, the small San Franciscan group glows with an earned pride that would make Teddy Roosevelt’s tattoo proud. In a city dominated by connection through ghostly screens and the closest daily contact to nature probably being our fingers on computer mice, planting a tree feels like the most necessary — and radical — of San Francisco acts.

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