Mount Sutro

Historical Essay

by Elizabeth Creely

The Seedbank of Mount Sutro

Mount Sutro, a hill in San Francisco, is difficult to characterize. At 908 feet, it’s a very tall hill that comes close to being a small mountain. (Another 92 feet, and it would have that distinction.) Many hundreds of years ago it might have started life as a hybridized sand dune/chert rock outcropping: it sits to the south of the Great Sand Bank of the outer lands of the city where offshore gusts threw sand from west to east with impunity one hundred years ago. It has a lot of trees growing on it, so many that it’s called a forest, although properly speaking it’s more like a tree plantation. Most of the trees are from one species, Eucalyptus globulus, the Tasmanian blue gum eucalyptus. When Mount Sutro is viewed from a distance, it looks almost cartoonishly rounded, a great tree-laden lump rising in the center of the city. The ravines and slopes of Mount Sutro are filled with blue gum eucalyptus, Himalayan blackberry and English ivy. They are all non-native.


Sutro Forest in its usual fog, 2011.

Photo: Chris Carlsson

Craig Dawson, the executive director of Sutro Stewards, a habitat restoration organization, likes eucalyptus trees and prefers the native blackberry over its invasive cousin. “Native blackberries are sweeter,” he says. “Himalayan blackberries are really tart.” He is openly dismayed by the English ivy, Hedera helix, the villainous plant of the understory which prevents native plants from growing well or at all and kills eucalyptus trees. “The birds eat the berries,” he says, “and the seeds gets distributed everywhere. You can’t fight all this,” he says, gesturing at the glossy leaves of the ivy.


Sutro forest overrun with ivy.

Photo: Chris Carlsson

He plans to fight it. Craig founded Sutro Stewards in 2006. He, along with a cadre of volunteers, has begun the great work: the restoration of trails, and the excavation of Mount Sutro’s centuries old seedbank, which is buried under masses of brambles and vines.

The University of California San Francisco (UCSF) owns the sixty-one acre Mount Sutro Open Space Reserve. After participating in a three-year consensus driven discussion among people Craig has described as “folks who never wanted to see a tree cut”, UCSF issued a long-term management plan in the fall of 2001. Even after the lengthy huddle, the plan still faced opposition. Undeterred, UCSF issued a Draft Environmental Impact Report (DEIR) this year, which proposes to ease into the forest management thusly: four project areas will undergo tree thinning, invasive understory removal, and other tweaks to the ecological system currently ruling the forest. The idea is to broaden the biological diversity of the reserve. How many trees will be removed from the project area? “That number hasn’t been quantified yet,” said Dianne Wong, Environmental Coordinator for UCSF. At full implementation of the plan, 60% of all eucalyptus and blackwood acacia could be removed. UCSF will work with a forester in the fall of 2013 — “We’re behind schedule,” Wong told me, ruefully—to finalize the number and begin work in the project areas. Less than eight acres of the reserve will be under direct management, and only one of the project areas, demonstration area number four, will be planted with native plants: a modest gain for California coastal scrub, and its human allies.

The reserve has been thinned twice, but it’s hard to tell. “Sutro didn’t just plant eucalyptus trees here,” says Dawson. “He planted them all the way to Monterey Boulevard.” Adolph Sutro, a civic-minded man and one-time mayor, deciding that San Francisco’s sandy hills needed trees, purchased the remains of the old 1,200 acre Rancho San Miguel and planted millions of them on the lands that lay to the south and the west, now the neighborhood known as the Inner Sunset, creating anew what he’d grown up with in Prussia: a deciduous forest with deep groves and “song haunted shadows.” Sutro planted Monterey Pines, Cypress, and a fast growing tree, the blue gum eucalyptus. The eucalyptus, along with oak trees and Monterey pine, quickly became enshrined in California’s natural and cultural landscape. The tall trees were irresistible to artists like Arthur and Lucia Matthews, who used their slender trucks and spreading canopies as backdrops to women wearing togas and disporting themselves en plain aire. Anyone who grew up on California’s coastal plain has seen oaks and eucalyptus together in the foothills, sibling trees standing side by side.

California’s mentholated eucalyptus groves are spectacular after a rain, cool and fragrant. When the winds blow through a eucalyptus grove, the sound of their limbs rubbing together creates a mighty chorus: a sylvan string section tuning up, preparing to synchronize their deep groans into one mighty song.

“We call these branches widow-makers,” remarked Craig one sunny Sunday afternoon, looking at a eucalyptus branch which had fallen. It was resting at an odd angle, wedged between another branch and the tree’s trunk. “We find stuff across the trails all the time,” Craig said. “We were here last weekend, with a bunch of volunteers, when about twenty feet away a huge branch came down. It was about twenty feet long. It just broke loose and came crashing down,” he said. The branch fell because of the heat. “Eucalyptus drop branches on warm days. They’ll shed an upper-story branch with no notice.” Craig and I had met in a parking lot within the reserve on Mother’s Day for a quick tour of the reserve, which turned into a three-hour hike. Craig, who owns a graphics shop, is a local boy who grew up in the Forest Knolls neighborhood and spent his boyhood exploring the forest as a kid. Back then, there were open spaces and you could see more—native grasses and Douglas iris, the entrance to the Bay, the western expanses of the city and the ocean, the interior of the Bay with the triangular cap of Mount Diablo peeking above it. Not now.

We entered the Historic Trail that runs along the edge of Woodland Canyon. Craig started naming plants as we walked, each name punctuated by his footfall. “Elderberry. Wild Cucumber. Cape Ivy—invasive. If you leave one little node of this, it’ll take over. It’s deathless.” He pointed to a plant sitting in a shaft of sunlight that shone through a gap in the eucalyptus canopy. “This is elk clover,” he said in the tone of a proud parent. “It’s very rare. We found the mother plant on top of the creek.” The plant looked unremarkable—broad-leaved, with herbaceous stems tinged red—but its difference made it a novelty from the endless iteration of ivy vines and blackberry canes that filled the ravine floor.

We were standing in the oldest part of the forest. Ivy climbed every tree, creating a grove of parenthetically-shaped trunks bent like bows. “It’s dying a slow death,” said Craig. “We don’t need to take trees out here. The ivy is killing these trees by smothering them.” The slopes, Craig says, are fragile and unused to the weight of a tree festooned with pounds of ivy. “It’s a big strain.” UCSF confirms this: rock outcroppings have “failed” because of tree roots forcing their way under the soil and popping the reddish boulders out of their socket. The overwhelming color throughout the ravine was lusciously green, so profuse that the air seemed to vibrate. But something was missing. “There is no new growth here,” said Craig. “People come through this canyon and what they see is a lot of green. It’s mystical, it’s magical. But green is not always healthy.” Invasive plants do more than lock up habitat: they also devour the systems they created. “Green doesn’t mean health and vitality. Green, in this instance, means the death of these trees,” said Craig. He walked over to the edge of the ravine and clambered down its sides.

Craig was up to his hips in the deathless understory looking for something he’d spotted days before: a trillium, a rare native plant with a white, star-shaped flower and voluptuously fan-shaped leaves. Trillium is usually only seen in wet redwood forests north of Mendocino County. He found the plant, but the flower was missing. He sighed. “It was in flower,” he said, almost to himself, and looked around for a few minutes. Someone may have picked it in an attempt to propagate it, he said, walking back up to the trail. Or maybe they just picked it. A group of hikers drew abreast of us.

“Hi there,” called Craig. One of the hikers looked puzzled. Sensing a teachable moment, Craig asked, “You folks know what you’re looking at?”

“Not really!” she replied, brightly. She wanted to know the name of a shrub with a large purple flower.

“That’s kangaroo apple. It’s a flower from the nightshade family. It isn’t native,” said Craig. Later he said, “Half the battle is getting people to observe. They need to know exactly what it is they’re looking at.”

Perhaps the most important and the slightly magical part of conversion planting is exposing the seed bank: the millions of seeds buried in the soil, left by the plants that slowly suffocated under the thick mat of the understory. When the thick 15 foot mat of brambles and vines are pulled up, and the trees are thinned, the soil will be exposed to the sun and long-dormant seeds come back to life. “Some lupine can last for a century,” Tom Parker, a Professor of Biology at San Francisco State University told me. “That was shown in downtown San Francisco. Construction workers started excavating a site and lupine bushes started sprouting.”

Craig is counting on this. “Listen—we didn’t plant hardly any of this,” he told me over his shoulder. “We didn’t have to. When you light up the forest floor, the native plants come back.” Sutro Stewards maintains a native plant nursery that hosts hundreds of plants sprouted from seeds painstakingly harvested from the diasporic community of native plants found in the reserve and surrounding areas. It’s easy to see the nursery as Craig’s version of Noah’s Ark and the reserve as a diluvial landscape, deluged by a relentless green ocean. The forest isn’t missing as much as it’s displaced. At the moment it’s either growing in planters in the nursery, or lying dormant under the towering dominion of the eucalyptus forest: a coastal shrub community frozen in time, waiting for the dissolution of the partnership between ivy, blackberry and eucalyptus. We walked out of the canyon and headed for the summit.

The North Ridge Trail is steep. I huffed and puffed after Craig, while he continued to name plants as he went. We stopped before a tall tree. “Toyon,” said Craig. We looked at it in silence. Here was a tree, solid and growing confidently in its old home. Maybe it had always been here— a historic remnant of a once larger community. Or maybe the seed it sprang from had been scarified in the acidic confines of a bird’s digestive tract and shat out to land— miraculously— in the one place it could sprout. We didn’t plant hardly any of this, Craig had said. Overhead the ravens croaked and chattered. Craig looked up in amusement. “When the ivy is in fruit, you can’t hear yourself talk. They’re very loud,” he said. Seed bearers to blackberry and toyon alike, they proved one thing: Invasion depends on movement. All things that creepeth and crappeth add more weight to Mount Sutro’s unbalanced ecological system, top-heavy with homogeneity. The current ecological system in the reserve depends on movement in the sky and on the trail below: hikers, bikers and birds all help propagate the eucalyptus, ivy and blackberry. We walked out of the murky confines of the reserve and into the summit. I saw the first direct sunlight I’d seen since meeting Craig in the Parking lot.

Rotary Meadow sits on about two inches of topsoil. The dirt was removed during the construction of a Nike radar base in the 1950’s. In an email sent to me later, Craig elaborated: “Rotary Meadow is planted in a debris field of unconsolidated rubble atop solid chert. On the top there is a bare minimum of a couple of inches of gravel, rock chips, and 50 years of composting resulting from the broom, blackberry and weeds that called it home.” The summit plant community, fragrant with mugwort and artemisia, is scraping by. It’s the only place in the reserve that supports a coastal scrub community. It does so on just under two acres of land.

Two bush lupines sat alongside a San Francisco gum plant. The lupines, small and fragile looking, are the only source of food on Mount Sutro for the tiny and endangered Mission Blue butterfly. “They’re no bigger than your fingernail,” said Craig, extending his for comparison. The lupine is also the butterfly’s nursery. The butterfly sips nectar from the lupine and lays its eggs on the underside of the leaves. The eggs hatch in six to ten days and continue feeding and living on the plant as caterpillars. The caterpillars are protected from insect predators (mostly wasps), by ants. Lupines, butterflies, ants: this elegant triad illustrates the basic schematic of ecology: a relationship between locale, plant and animal that is historically congruent and interdependent. It’s simple and very easy to disrupt. On Mount Sutro, the relationship is struggling. Two elements are missing: the butterfly and the ant.

Prenolepsis imparis, the ant, is missing. The ant/nursemaid to the Mission Blue caterpillar feeds on honeydew, a substance secreted by the caterpillar. The ants defend this food source from other predators like wasps. But a 2008 study performed jointly by biologists from San Francisco State University and the California Academy of Science described a startling finding: the absence of any native ants— any ants at all— in the interior greenbelt of Mount Sutro, downhill of the summit. The ant, it was surmised, was missing so completely because of the absence of habitat. Like elk clover, ants need the sun. And like mice, ants also need bare patches of land to travel. The study concludes that dense understory plants and too much moisture discouraged the ants from making it to the summit, effectively removing one crucial element from the three-part production that results in a population of healthy lupines and adult Mission Blue butterflies. The understory rolling and tumbling in the depths below affects the summit ecology dramatically: People literally can’t see the ants because of the trees.

A look of consternation flitted across Craig’s face. “Look at that,” he said. I looked. Purple star thistle had sprouted in a recently cleared patch to our right. “Workmen brought that up here,” he said. He said nothing more: he didn’t need to. Purple star thistle is a “major problem” according to the California Invasive Plant Council plant; the sort of plant that people who manage urban forests and regional parks cite as an example of why herbicides must be used.

Two herbicides are proposed for use in project area number four: glysophate and triclopyr Butoxyethyl Ester. This proposal has elicited responses ranging from outrage (“I remain vigorously opposed to the use of herbicides on Mount Sutro!”) to endorsement (“Aquamaster is noted as controlling eucalyptus. Perhaps you should include it as part of your stump treatment protocol.”) No one seems particularly happy about herbicides, but in the battle to reclaim territory for coastal shrub, happiness may lose to brute efficacy. Both herbicides have intimidating chemical profiles:

Triclopyr in particular is trans-dermal which is problematic for female workers- it’s been implicated in congenital birth defects. And the chemical proves Craig’s point that growth isn’t always a sign of health: it kills plants by provoking rapid cellular growth, making them grow too quickly. Glysophate is in wide use: Sunset magazine recommends it to control blackberry and Bermuda grass and the California Department of Fish and Game uses glysophate to control water hyacinth, an invasive water plant, in the Sacramento-San Joaquin Delta region. Both glysophate and triclopyr are used by the Natural Areas Program which is a branch of San Francisco Recreation and Park Department to control invasive species. For a controversial tactic, it’s in wide-spread use. Everyone’s doing it.

In an email to me, Craig said, “Non-herbicide methods are limited to pulling weeds by hand. This has been proven to be a waste of time. A crew of volunteers can work a few hundred feet of trail on a volunteer morning. We have 5 miles of trails. If weeds aren't removed immediately before they produce seed, you have effectively ensured a 5-10 fold increase by next year.” In his comments to UCSF’s DEIR he was more direct: “You must use herbicide on Acacia! Roots will re-sprout for years without it!”

Interventions into the insular community of invasive plants call for drastic measures; this seems to be accepted tacitly, although not happily, by biologists, field ecologists, and stewards who face off with eucalyptus, water hyacinth, and acacia day after day. UCSF is proposing a cut stump and foliar application, a plant-by-plant process that was adopted to appease fears of spraying herbicides over large areas indiscriminately. But success in limiting its impacts to individual trees and tree stumps depends on so much: the care taken by the worker, the oversight of the process. How careful will the workers be? Will fog dripping off the canopy or rain falling from the sky, distribute the herbicide?

For the general public, living on the margins of (or downstream from) urban forests, the use of glysophate and triclopyr seems not to be accepted at all. Tired of high-handed interventions into the earth’s ecological systems, they’re perhaps protesting not only an intentionally toxic process, but also the seemingly endless interference, or management, of meddlesome humans. When will the earth be left to itself? Craig looked at the star thistle disgustedly. We walked on.

We entered the south ridge, project area number one. The south ridge has been thinned not once but twice; first in the 1930’s when the Works Progress Administration employed local men to log the eucalyptus grove, (there was a mill on Seventh Avenue and Clarendon) and again in 1954 to make room for a new Nike Missile radar base. “These trees are 58 years old,” said Craig and they look it: epicormic shoots sprout weirdly from the sides of the trees, evidence of logging, military installations and the most common method of thinning, fire. There have been seven fires in the reserve since the late 1800’s. The largest, in 1899, burned 60 acres, practically the entirety of the reserve. Another fire in 1935 burned ten acres and took 400 firemen to extinguish. Mount Sutro, with its wet western perimeter and persistent fog, is not exempt from California’s fire ecology. In California, everything can burn.

The California Department of Forestry and Fire has ranked the Mount as a moderately dangerous for fires and ranked the fuel load as “very high.” In the interstice of these two classifications rages a debate about possibility and probability. There’s a lot of faith in the reserve’s innate ability to resist fire because of the fog that swaddles the south and the west sides of Mount Sutro. The faith is not misplaced—the fog is indeed formidable when it’s around— but in late August and early September, the fog is not always there. “People think that the fog is always in and that it’s always there. And I say bullshit,” said Stephen Finnegan, a fireman who lives in Forest Knolls. “The fog is not always in and it’s not always there.” He isn’t too concerned about the possibility of fire—“it would take a highly motivated arsonist”-but allows that the potential is there. The climate is changing. California is getting warmer and drier. CAL Fire’s Fire and Resource Assessment Program notes that the fire season in California is starting earlier and lasting longer.

Andy Hubbs, forester and vegetation management program coordinator for the California Department of Forestry and Fire Protection, can’t say for certain what the future holds, but he clear about the kind of fire he’d rather fight: a flaming bush. “I’d definitely rather fight a fire that started in coastal scrub than in a eucalyptus grove. Eucalyptus trees are volatile,” he said when I put the question to him. “Bay laurel trees also have high oil content. But they aren’t as much of a threat because they aren’t as tall, and they tend to exist in heterogeneous plant communities that produce less litter. The leaf litter under a euc can be 2 to 3 feet deep. And their bark peels off and adds to that.”

Fire, like ivy and blackberry, also depends on movement for propagation. Eucalyptus boosters of the late eighteen hundreds, envisioning cheap available wood, noted correctly that what a eucalyptus does extraordinarily well is grow. But it has another talent: hurling embers. The long curved leaf of the eucalyptus is “susceptible,” in the words of the authors of one report on the Oakland Hills, fire to “spotting” or to floating along effortlessly in the wind, carrying the fire with it. “Tree height has a lot to do with flammability,” said Andy. “We calculate fire height to be 1 ½ to 2 times the height of the plant. A fully involved euc stand means a fire height that can be anywhere from 150 to 300 feet high. No person can get near that.” Fire throwing increases the ambient heat, too: The eucs involved in the Oakland Hills fire are estimated to have contributed 70% of the convection energy produced by the fire. “The heat intensity is much higher because of the flame height,” said Andy. “It depends on the height of the tree and the speed of the wind, but an ember that flies a mile to five miles out in front of the fire is not out of the question.”

It isn’t. On the morning of October 20, 1991, I sat in the kitchen of my apartment in San Francisco looking at the sky. The atmosphere was tinged orange. Although it was late morning, it looked as if the sun had already set—an old sky for a new day. A fat flake of ash sailed in through the open window and settled gently on the top of my milky coffee. This, I learned about an hour later, when I turned on the news, was the ash of an ember, small and potent, that had blown all the way across from the massive fire ripping its way through the Oakland Hills. Did it come from an inflamed eucalyptus tree?

In the battle to understand and manage the future, one fire regime tends to gets pitted against another. Chaparral is dangerous, say the critics of the UCSF forest management plan. Grasslands are dry. Coastal scrub doesn’t harvest fog or moisten the soil as efficiently as eucalyptus trees do. Eucalyptus trees explode, counter indignant Californians weary of hearing their native plant communities maligned. They increase the fuel loads to dangerous levels. They hog water. They perpetuate a mistaken vision of beauty for California: one that lionizes imported trees, while the glory of California’s coastal scrub and chaparral gets denigrated as dangerously “dry” brush with little or no regard for the astonishing amount of biodiversity it promotes. But the words of Andy Hubbs resolve this argument: “Everything burns,” he said. Eucalypts, native chaparral, southern coastal scrub communities, and the type of maritime coastal scrub/chaparral plant community that once grew on the hills in San Francisco- all of it.

In California, everything burns.

As Craig and I walked through the south ridge, the change in ambient moisture was abrupt. Minutes before the air had been fairly dry. Now dripping water fell everywhere. We were in the fabled “cloud forest” of Mount Sutro, standing in fog so thick that there was nothing to be seen but tree after tree, shrouded in whitish-grey mist. “You should be able to see the Marin Headlands from here,” said Craig. I felt like a ghost standing there. There’s an odd lack of “place” on Mount Sutro, a landmark isolated from its cousin landmarks, the Marin Headlands, the sea, and the southern reaches of the San Miguel Hills. There is no context to widen the understanding of what you’re standing on, no chance to compare the hill with other hills, bluffs and beaches. There is no way to appreciate the contiguity of the coastal ridge that runs from Point Reyes down the peninsula. One is forced to consider only the spindly trees and the shrouding fog. We walked back to the parking lot. Craig pointed to a eucalyptus tree. “See that? That’s what a healthy euc looks like,” he said. I looked at it and saw what I’d been looking at my whole life, in paintings or in windbreaks that edge the 101 freeway: a magnificent tree with a truck the color of pale ivory and a crown of dark green leaves radiating horizontally from the branches. It was the very picture of edenic California, lovely, healthy and serene.

We love what we know. Perhaps California’s native plant landscape is not loved more because it’s been lost to hundreds of years of intensive development. Fire and herbicides aside, what seems to be creating the most dissent is the prospect of a “forest” adulterated by a plant community which is still— oddly —unknown. The ceanothus and the coyote brush, toyon and artemisia, strangers in their own land, might have a public relations battle to win.

I think that I shall never see a bush as beloved as a tree, I thought, mangling Kilmer’s wistful poem in my head as I walked down the hill to Parnassus Street. Not in California, anyway. Whether the good people of Midtown Terrace, Forest Knolls, and Clarendon Heights know it or not, they are looking at a landscape which is being managed by the triad of ivy, blackberry, and blue gum. The final haunting vision of Mount Sutro is one of endless recursion; an algorithm that perpetuates a design of exclusion. Mount Sutro, if it is left to its own devices, will be unable to refer to anything but itself, enduring biological isolation from the natural world surrounding it in all the tomorrows to come.