Sutro Forest: Risk and Uncertainty

orange paintUCSF’s sent out another notice for tree removals. Presumably, these will be the remaining trees  marked with orange dots last year.  It’s the middle of the nesting season now, and we do not understand either the urgency — or the need. Why can’t these trees – very few of which are actually hazardous – wait a few months to save young wildlife?

[Update June 2014: Some 212 trees were actually cut down. Since it’s nearly impossible to find songbird nests without prolonged observation, we expect there was some damage/ mortality.]

We also have more serious and long-term concerns about UCSF and Sutro Forest:

  •  That “safety” will be an excuse to cut down a lot of trees and destroy the understory; and
  •  That the management of the forest may fall to those who despise it.


bushtit with nesting material. Copyright Janet Kessler

Bushtit with nesting material. Copyright Janet Kessler

We’re grateful that (until this March!) UCSF has generally respected this downtime allowing birds and animals to breed and raise their families in Sutro Forest. This is not just theoretical. Wildcare, a wonderful organization that cares for injured or displaced wild creatures – including young birds and animals in the breeding season – has an important advisory on their website: Stop! Don’t Prune Those Trees. It say, in part:

“WildCare asks you to please stop and consider the time of year– if it’s spring or summer, animals of all species may be using your tree as a nursery even as you read this! Every spring, baby animals that have been orphaned or injured because their nests were damaged or removed arrive at WildCare… Some species of birds (especially raptors) nest in hidden tree cavities, so don’t forget to check both limbs and trunks thoroughly before trimming or removing. Spring (and summer!) are busy baby season— procrastinate now!”


In its forest plans, UCSF  always earmarked the period between mid-February and mid-August as the nesting season when it would do only emergency work.  UCSF’s had good track record on respecting this.  Last year, it postponed an experiment with using goats to reduce underbrush when people pointed out that birds do nest in the understory.

So we were quite  surprised recently that it started tree removals in March 2014, and didn’t heed requests to wait. Some 181 trees had been marked with orange dots, and about half of them were cut down in March. Now, it’s doing the rest. Here’s what they wrote.

“Starting on Monday, May 5, [2014] Bartlett will return to complete the work. There will be intermittent trail closures on weekdays from May 5 through May 23 as the work is being completed, and Bartlett will avoid any noisy work before 9 a.m. Again, this work is focused only on mitigating the potential danger of hazardous trees.”

We wrote to them pointing out it was the nesting season. They replied:

“Thank you for your email regarding bird-nesting season. We are aware of the bird activity in the Mount Sutro Open Space Reserve, and UCSF Facilities Services has a policy to avoid tree removal and pruning if there is active bird-nesting in the tree.  Hazardous tree work is a critical part of our ongoing maintenance program. In the interest of the safety of visitors to the Reserve, this work needs to happen as soon as possible. Again, we appreciate your patience during this work and encourage you to use caution when visiting the Reserve.”

But it’s really difficult to know where birds and animals hide their nests and dens. When there’s disturbance, the parents stay away from the babies. They have to be good at it, or their young will get eaten. It’s unreasonable to expect Bartlett, the tree removal contractor, to responsibly check each of a 100 trees for nesting activity.

This bewick's wren's nest is hidden. Copyright Janet Kessler

This Bewick’s wren’s nest is hidden. Copyright Janet Kessler

And since dead trees (snags) are particularly excellent for wildlife, we can assume that there will be destruction.

snag as hunting groundWERE THEY HAZARDOUS?

We wrote about the trees being marked with orange dots at the time this was first done. Many people objected; some even left notes on the trees.

When arborists examine trees for hazard, they look at how likely the tree is to fail, how big it is, and where it would land.  Hort Science’s method considers three factors:

  • Failure potential (How likely is it that the tree would fall or drop a limb);
  • Size of the part that would fail (the size of the tree or the branch);
  • Value of the target area (if it fell, what would it damage?).

Each is scored on a scale of 1-4, and the scores are added together. This gives a tree a rating of 3 (least problematic) to 12 (most problematic). Only a small young tree far from any road or building or playground would be a 3. The City’s action threshold is 9, and most trees with a 9 or higher rating would be removed.

trees with orange blobsThis methodology is strongly biased against large trees in busy areas. For instance, a big tree near a roadway would get a score of 4 for size, and 4 for “value of target.” This means it is an automatic 9, because the score for “failure potential” cannot be less than 1. But conversely, it does not remove trees merely for being old or spindly or even dead.

Unfortunately, they don’t usually employ this method for natural areas and forests.  There, they just eyeball the trees, and mark for removal any that are in poor condition or are leaning. We suspect the approach used here was just that – remove trees that are dead or dying or leaning.

Very few of these trees were actually hazardous. All of them add to the forest’s character and provide important wildlife habitat.


While our immediate concern is with tree felling in the bird nesting season, we have several longer-term concerns.

  • “Hazard” as an excuse for causing more hazards by felling trees.  “Hazard” – whether for trees in poor condition, or the so-called “fire hazard” will be used as an excuse for tree-felling – while ignoring the real and long-term risk of destabilizing the slopes. Scientists believe a tragic landslide in Oso, Washington was due in part to trees being cut above the slope that failed. Rockslides and failures can occur for many years after trees are felled. (We wrote about that HERE.)
  • Managers who hate non-native trees. UCSF has also hinted that it is unsure how to proceed with managing the forest, saying their expertise is in medicine, not forestry:  “…the University is exploring a variety of partnerships and other resources that could provide help and guidance in its stewardship of the Reserve.”  This understandable. Our concern is with the nature of this help and guidance – and the potential use of the nativist “Natural Areas Program” guidelines.


Last year, San Francisco’s Department of the Environment hired Peter Brastow as ‘Senior Biodiversity Coordinator.’ Before that, he was Director of ‘Nature in the City’, the original parent organization of the Sutro Stewards. He’s been tasked with putting together a “Biodiversity Plan” for the city, and they are seeking a $0.25 million grant from the Strategic Growth Council to do this. (The Strategic Growth Council is a California state organization.)

This Plan is hugely problematic on two counts.

  • First, the ‘biodiversity’ being considered is an extension of the controversial and destructive Natural Areas Program (NAP) of the San Francisco Recreation and Parks Department. NAP seeks to destroy thousands of trees, close many miles of trails, and already uses more of the “most hazardous” herbicides than the rest of SFRPD put together (excluding Harding Golf Course, which is managed by the PGA Tour and not by SFRPD).
  • Second, it plans to extend this Plan to all the open areas of the city, no matter what the ownership. It would even include people’s backyards. UCSF would not be bound by a city plan, since they are a State-level organization. But they could use it as an excuse to implement something similar.

Biodiversity is a poorly defined term, and as Professor Art Shapiro pointed out “Biodiversity means whatever you want it to mean.” The promoters of this Biodiversity Plan are not friendly to trees, particularly non-native trees. In a recent meeting of the SF DoE, Peter Brastow commented on the Urban Forestry Plan – which seeks to stabilize and then expand San Francisco’s sparse 17.3% tree canopy – with “You can’t plant trees willy nilly” and noted that the tree-canopy objective could conflict with the “biodiversity” objective. In a meeting we attended some years ago, Peter Brastow called eucalyptus “the largest weed.”

Clearly, how they define “biodiversity” is “native plants and shrubs.”

We oppose this Plan, which could have far-reaching adverse consequences for our city and its environment. Trees sequester carbon, fight pollution, provide windbreaks, absorb sound, and stabilize slopes in ways that low-growing plants and shrubs cannot do. Trees are more environmentally valuable, and expanding the tree-canopy is an important objective – as is preserving what we have in Sutro Forest and elsewhere.

It’s a poor idea. It’s based on NAP, whose own Management Plan is still undergoing a million-dollar Environmental Impact Report process that may take until the end of 2014. It covers private property, including, specifically, people’s back yards; it’s not impossible that homeowners would find they needed permission in deciding what to plant or how they manage their own spaces if the Plan produces guidelines that get written into regulations. It doesn’t clarify how this whole effort will be funded.

We hope that the Strategic Growth Council will not waste our money funding this anti-environmental effort. The decision whether to consider the proposal will be taken on May 15th, 2014. The person to write to is Polly Escovedo (

Formerly trees

Formerly trees

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5 Responses to Sutro Forest: Risk and Uncertainty

  1. Pam Walatka says:

    Thank you Save Sutro Forest people for this thoughtful and important piece. Keep up the good work.

  2. Tony Holiday says:

    Get rid of these people before they cause any more damage. They are causing far more harm than good. And to think some of these nuts want to tell people what they can and cannot grow in their own yards is unbelievable. What have we done to deserve these crazies?

  3. Tony Holiday says:

    Why do I keep getting all these “confirm follow” requests lately when I comment when I’ve done this a bunch of times before?

    [Webmaster: Seems that WordPress – the platform this website is using – is doing it as abundant caution, to prevent it from sending out spam. We have the same experience when we try to follow comments on other websites.]

  4. Pingback: “Gardening for Climate Change” | Death of a Million Trees

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