Helping the Canyon thrive through judicious pruning

Jenny Sotelo, Steven Uchida and Georgia Fie pushing back Cape ivy above Silver Tree Summer Camp

By Murray Schneider

Willow Creek Trail isn’t named on any official map that San Francisco Rec and Park has shelved at McLaren Lodge. Nevertheless, the Glen Canyon path circles Glen Park’s Islais Creek. It begins near a boardwalk that leaves Silver Tree Day Camp in its wake, runs parallel to a seep that collects run-off water from Diamond Heights and continues beneath canopies of arroyo willow and solitary strands of California blackberry that dangle like errant embroidery from a quilter’s needle.

Angling left, it passes over a railroad-tie-sized-chunk of wood acting as a single-file bridge above a nascent puddle yet to turn into succulent mud. Then, on the west side of the creek, it inches past invasive Himalayan blackberry whose stalks are pregnant with spiky thorns. Finally, the trail moves past beds of reintroduced native plants whose purpose is less aesthetic or nostalgic than it is to promote habitat diversity in San Francisco’s bucolic 70-acres natural area.

Recently planted Columbine surrounded by straw to protect it.

On the Wednesday before Christmas, Dylan Hayes, 40, a Rec and Park Natural Areas gardener, stood near a bank of Islais Creek, on the west side of a cedar-rail fence constructed by Friends of Glen Canyon Park, studying pink-flowering currant and columbine, both planted only three days earlier by volunteers from the same organization who built the split-rail fence three years ago.

The plants were thirsty, parched from the absence of December rains. “We’re interested in a variety of shrubs that are links in the food chain,” Hayes said. He pointed to dozens of plants, each surrounded by protective blankets of straw, which are designed to suppress weeds and to keep the dry soil moist. Both the columbine and pink-flowering currant hugged an incline that would eventually climb to the O’Shaughnessy Boulevard frontier. Kneeling down, Hayes brushed away some straw and fingered a stem of columbine. “It’s great food for moths, beetles and caterpillars.”

Hayes dressed in a fleece vest over a maroon long-sleeved T-shirt, both embossed with patented Rec and Park logos. Bright and crisp, the early morning signaled a chill. He wore Wellingtons since earlier he’d dredged pools of slow-moving water, like a mid-western kettle hole, above the seep from where wildlife drink, clearing it of choked detritus, making it user friendly for critters such as raccoons and coyotes.

Natural Areas gardeners and Friends of Glen Canyon Park clearing Cape ivy.

“The chorus frog drinks from up there,” Hayes said, pointing to the tawny hillside on the other side of the creek where amphibians croak springtime medleys of mating songs.

He continued to gesture to the hummock above the seep, home to hillside oaks from where red-tailed hawks hunt, their sharp eyes zeroing in on rodents coyotes may have overlooked.

“I call the pools the coyote baths,” he said. He fished an iPhone from his Levi’s and tapped an icon. A video of a grazing coyote appeared on the screen. The animal stretched and began moving at a snail’s pace toward the water hole.

“Coyotes are omnivores,” he said, pocketing his phone, “requiring a daily diet of voles, gophers and berries to maintain their mass.” Hayes has worked for the Natural Areas program for seven years, and it doesn’t take much prompting for him to stop what he’s doing and offer a mini-lecture on the ecology he’s entrusted to safeguard. His Recreation and Park Commission mandate is that of a steward of the Glen Canyon. He takes his empowerment seriously, ensuring the canyon’s preservation and assuring that day users have access to it, using it in symbiotic harmony with indigenous habitat, both plant and animal.

As the sun peeked through willow branches sheltering song birds, he tutored a Friends of Glen Canyon Park volunteer, demonstrating how best to sculpt berms that surround each native plant and then douse each with correct amounts of water.  “Work your way down the line,” he instructed, “and then give them a second and third drink.”

The volunteer scooped ladles of water from a five-gallon container and anointed each plant, the liquid soon absorbed by the dry ground. “When the flowers bloom they become nectar to humming birds,” said Hayes, sounding every bit like a high school sophomore biology teacher. “In the winter, honey bees like them, too.”

He walked along the remaining reaches of Willow Creek Trail where Silver Tree’s bunker-like building hulked in front of him. Integrated among tall redwoods, a stand of eucalyptus trees towered in craggy spires, their deciduous leaf duff snapping under foot. The non-native gum tree, brought to California in the aftermath of the Gold Rush, has become an adoptive sibling to native conifers, its pungent perfume ingratiating itself to generations San Franciscans who have grown up surrounded by these giant Australian imports while rounding the western edges of Golden Gate Park and hiking atop Mt. Davidson.

But the shallow-rooted eucys need caretaking. Hayes pointed to a limb that crackled. It hung where Glenridge nursery school children, now on Christmas holiday, normally play. A similar Sigmund Stern Grove branch fell years before, causing the death a gardener. When branches fall along Willow Creek Trial they drop almost in slow motion, cracking from the girth of the tree, echoing like lightening in a thunderstorm.

Dylan Hayes viewing a blackberry leaf in Glen Canyon.

“We’re all about habitat diversity,” Hayes said. “We aren’t about wholesale tree removal, simply managing them.” He detoured above Silver Tree’s cement picnic benches where six volunteers worked, ankle deep in colonizing Cape ivy. Using three-pronged rakes, they muscled wide swaths of the invasive plant into mounds, making skirmish lines much like fire fighters do when they combat wilderness blazes.

They wrestled with pyramids of ivy, forming scrum lines in an effort to shoulder the inimical ivy up the hill. “Many hands makes light work,” Hayes said, reminded that the underfunded Natural Areas Program relies upon volunteers.

Critics of the Natural Area Program see its efforts as destructive to animal habitat, where pruning a willow branch is akin to clear-cutting a forest, where the occasional use of multi-faceted integrated pest management is tantamount to wholesale and irresponsible herbicide saturation.

NAP sees natural areas not as battlegrounds but natural park grounds, multi-use venues where wildlife, plants and people co-exist in symmetry.  “Cape Ivy is a monoculture all to itself; it expands and threatens other species,” Hayes said.

He pointed up the hill to a variety of native shrubs. “All of that,” he said, in a calm and measured tone, “that’s monkey flower, coffee berry, hillside pea, elderberry, California blackberry two species of fern, even coast-live oak.”

Dylan Hayes inspecting coast live oak above Silver Tree Camp.

Left to its own devices, carpets of Cape ivy will spread amoeba-like, ascending the hill, strangling trees in its path, enveloping species after species. “What we’re doing is defending an intact food matrix,” Hayes said. “We’re clearing a defensive area, creating a barrier to prevent the continued encroachment of the ivy.”

Native to South Africa, Cape ivy has the ability to form a dense ground cover, climb trees and fences and other plants in such masses of herbaceous growth that it smothers everything beneath it.

Hayes leaned over and picked up a stem of ivy, appraised it and tossed it onto the burgeoning pile of its brethren.  “We’re banking on short-term disturbance,” he said, “for long-term multi-purpose gain.”

If anyone has a long-term view of Glen Canyon it is Carol Steiman who, with her husband Harvey, has lived at the end of Bosworth Street for 27 years. Remembering it as dark, dank and barely accessible nearly three decades ago, today they both routinely walk its paths, just as likely to come across Hayes’s City utility truck, as they are other day-trippers, dog walkers and rock climbers.

“It is much more accessible, much more cared for now,” said Carol Steiman, who registered her daughter, Kate, at Silver Tree Day Camp 20 years ago. “Now I see people sitting on boulders and walking deep into the canyon.”

Hayes looked up from a California blackberry leaf he’d inspected, holding it up for a volunteer’s perusal, studying where both larvae and adult insects fed on the leaf.

“Insects sustain themselves from it,” he said, in his best professorial voice, “but just as importantly, it produces some of the best bird habitat by providing deep cover that the they need for nesting.”

He looked back at a cluster of eucalyptus trees. “Blackberry scrub is another habitat shaded out by eucalyptus groves that are unmanaged,” he cautioned. “This allows the Cape ivy to proliferate, shading out any possibility of plant species living together to form a strong local food web.”

Across the creek he watched a column of children bookended by adults. They trooped Indian-file along a path where earlier he’d encountered the lounging coyote. Several of the children skipped and hopped, more than enough proof that Glen Canyon is a sanctuary not simply for shrubs and wildlife, its original inhabitants, but for the next generation who will share it with them.

Dylan Hayes, the father of a soon to be two-year old daughter, grinned at the tableau playing out before him. “I like seeing that.”

Photos by Murray Schneider


Anyone wishing to volunteer in Glen Canyon can contact Joel Grey, volunteer coordinator, at or at 415-831-6328.           



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5 responses to “Helping the Canyon thrive through judicious pruning

  1. We have been observing native plant restorations in the San Francisco Bay Area for about 15 years, including many of the so-called “natural areas” in San Francisco. Based on our personal experience and direct observation of the Natural Areas Program, we offer our perspective on several points made in this article.

    The animals that live in our parks make good use of the plants, whether they are native or non-native. Himalayan blackberries are just one of many examples of a non-native plant that is an important source of food for our animals and it also provides excellent cover for nesting and roosting animals. The animals don’t care if the blackberries are native or non-native. In fact, the non-native blackberry is considerably more productive than its native counterpart.

    Likewise, eucalyptus trees are one of the few sources of winter nectar for bees and hummingbirds in the Bay Area. Native plants are not blooming in the dead of winter, contrary to the belief of the Natural Areas Staff.

    Eucalyptus trees are not shallow-rooted, as this article claims. Unless they have been planted where there is shallow soil over a rock pan, they are deeply and firmly rooted. Eucalyptus trees are not more hazardous than any other tree. Although a gardener was killed by a eucalyptus tree in Stern Grove in the distant past (about 25 years ago), a woman was killed in Stern Grove in 2008 by a redwood branch.

    Just last spring a Monterey pine fell from its roots across a path in Stern Grove. The certified arborist (Hort Science) who evaluated that windfall stated in writing that the windbreak had been compromised by the removal of healthy trees by the Natural Areas Program. The removal of healthy trees makes the trees that remain more hazardous because of the loss of protection from the wind.

    In any case, the Natural Areas Program does not prune eucalyptus trees. Rather they remove them. The management plan for the Natural Areas Program identifies 18,500 trees over 15 feet tall for removal in the natural areas. The management plan identified 120 eucalyptus trees for removal in Glen Park in addition to the approximately 25 trees that were destroyed in 2006. None of the trees that have been identified for removal are considered hazardous. The Recreation and Park Department has the right and the obligation to prune or remove all hazardous trees. This is not the duty of the Natural Areas Program. We never oppose the removal of hazardous trees.

    Herbicide use by the Natural Areas Program is not trivial, as your article implies. Glen Park was sprayed with herbicides 12 times in 2010 and Twin Peaks—which is the watershed to Islais Creek—was sprayed 16 times. There is nothing “natural” about the Natural Areas Program.

    If providing habitat is the goal of the Natural Areas Program, they should destroy fewer plants and trees and plant more plants of their choosing. Critics of the Natural Areas Program do not begrudge native plant advocates their personal plant preferences. We are only asking that they quit destroying the plants and trees that the animals need and we enjoy.

    Thank you for this opportunity to share our perspective on the Natural Areas Program.

  2. Ted (Chenery St. neighbor)

    This story is wonderfully written that captures the essence of Glen Canyon. The Rec & Park Department gardeners and Friends of Glen Canyon Park volunteers, as well as many others who contribute in various ways, deserve recognition for the hard work and care that help keep the canyon beautiful. It’s worth noting that the San Francisco Examiner had a full page story 2 weeks ago about the controversial aspects of “nonnative” tree removal not only in the canyon but in other areas of the city too. There should be a method for neighbors to give input about these issues just like we’ve been able to do so for the playground renovation. At very least the use of pesticides should be fully disclosed, especially to those who live near the canyon and enjoy taking their kids, dogs and friends to experience the natural outdoors in our collective backyard. Happy trails and New Year to all!

  3. This is a wonderfully written story, but… what’s happening in Glen Canyon is not a benign “judicious pruning.” It’s a wholesale destruction of habitat. The coyotes fondly referenced have always been able to drink from the stream and pool; removing the brush destroys the cover they need to escape from people and dogs, and raise the risk of untoward encounters. The birds need the brush as cover to protect them from hunting hawks and as places to nest. The eucalyptus trees – many of which are slated for removal – are important both as cover, and because it’s a winter-blooming species that provides food for insects and birds at a time when few other things flower.

    I think the volunteers work hard and have a positive desire to contribute to nature, and probably have no idea how destructive some of the activities are.

    And the article glosses over the fact that Glen Canyon, in the last year, has repeatedly been the target of some of the most powerful pesticides the city allows. I agree with Ted above: The use of pesticides should be fully disclosed, in advance. As it is, we rely on people who see the notices posted a few days in advance to inform others.

  4. When asked what they wanted most for this park, those attending the meetings last year voiced their desire loudly and clearly: we want the park kept wild, we want the wilderness retained. Wilderness is the opposite of intense pruning, clearing, landscaping, and management.

    Everyone is alarmed and upset at the huge amount of clearing taking place in Glen Canyon. Unfortunately, what is going on is not “judicious pruning” which this article implies, it’s more like “vicious clearing” including the use of a work gang wielding chain saws — as many as six chain saw operators over a two week period in the park — we’ve never seen this before in the park. Neither have we seen entire hillsides denuded of native coyote brush, or native willows thickets reduced in size, thinned, and their underbrush removed.

    Our unique wilderness park is slowly being altered into a pruned garden of sparse native grasses and manicured slopes. A small field devoted to such a project, to show what historically might have existed in some parts of the city in 1776 would be fine. But altering the park into a nativist’s vision of what they think the park “ought to” look like is hurting our animal habitat, and altering the park as we know it and want it. It is also ecologically unsustainable without constant maintenance.

    Poisonous herbicides are being sprayed on cape ivy in areas that have been designated as “contiguous wildlife” area — wasn’t this wildlife area supposed to be left undisturbed? Ours is a canyon, and all poisons end up in the creek, a creek from which animals drink and where children play. We have been fighting the poisons to no avail. At the meetings, NAP pointed out cape ivy in the very back of the park as a possible target for removal. We agreed to this if and only if it was done incrementally, and only when a biologist from SOTA suggested that his students could do this by hand. NAP has taken the license to remove cape ivy wholesale in other parts of the park, using chain saws to break into and disturb remote areas used only by wildlife, and applying poisons to these same areas.

    Coyote brush and other hillside bushes and shrubbery constitute the protective habitat used by many birds and furry creatures. Dense thickets under the trees and along the creeks do the same. Animals don’t need “animal friendly” areas created by humans who don’t know or understand the parameters of what they need. Removing the brush that is covering the stream does not create an “animal friendly watering hole” — it removes the protective covering the animals have relied on for their safety. This clearing is actually “animal unfriendly” because it exposes the animals, especially the young ones, to dangers when they seek water and otherwise.

    Our park has been managed by “nature” for many years. Nature, contrary to what NAP gardeners and volunteers will tell you, achieves its own healthy balance. The health of an ecosystem is measured by the presence of its top predator. We have coyotes. Our ecosystem is very healthy. We should not be destroying it for the nativist fad which is being called into question in academic circles and by more and more ecologists.

  5. Dylan Hayes

    My name is Dylan Hayes, a Natural Resource Manager for the City and County of San Francisco’s Natural Areas Program(N.A.P.). I share the following representing only my own views.

    A big thank you to volunteer steward Murray Schneider for writing this article and working with me in Glen Canyon with San Francisco’s N.A.P. I would also like to thank the Friends of Glen Canyon for their tireless service and the thousands of volunteers who work with us at the N.A.P. throughout San Francisco! Your work is incredible and continues to make a difference in helping preserve and create a balance of habitats and park use for all creatures including us humans!

    Together, under the guidance of the Draft Natural Areas Plan, and the publicly well considered Environmental Impact Review of the twenty-year Significant Natural Resource Areas Plan, we will continue to responsibly maintain and honor our diverse natural heritage, helping preserve the unique landscapes and habitats that make San Francisco beautiful special via sustainable means.

    As a community we have done this work together on all fronts of park enhancement, whether it be habitat restoration addressing aggressively spreading introduced plants, picking up trash, trail maintenance and creation, planting local plants and trees or simply talking to one another about the issues of the day confronting our parks; you, the volunteers and your work are invaluable and appreciated more than ever in the midst of tough economic times!

    I for one appreciate and know your hands make the difference in the work we guide at the N.A.P. Our work is for wildlife in the short and especially long terms. We are here protecting the natural wonders within, not from you, but for you and our future generations of all species. We are using the best and safest techniques sanctioned by the Department of the Environment’s Integrated Pest Management Program. Yours and my health comes first!

    I am grateful to live and raise my daughter in this city and natural areas I was. I respect our place in history here. It should be understood that we all agree that we want to preserve the unique characters and values, “introduced” or “native”. I embrace the diversity of views and passion for life. However, I am also confident in my own and my colleagues’ skills and conscience at the N.A.P. Read and know the Plan seeks to preserve the maximum amount of species still here. Together we will continue to honor both us, and the nature in the city we’ve inherited.
    I thank you for supporting your Natural Areas Program and Plan and I’ll see you in the field!

    Dylan J. Hayes

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