San Franciscans come to the defense of the Sutro Forest

Mount Sutro Forest
Mount Sutro Forest

The San Francisco Chronicle recently published an op-ed by Joe Mascaro about the Sutro Forest (available here). He is a professional ecologist at the Carnegie Institution for Science who studies the ecological functions of forests (his research is described here). He is also a San Franciscan and a fan of the Sutro Forest. He tells us in his op-ed that the Sutro Forest is a unique, “novel” forest that is thriving and that destroying it will increase the risk of wildfire, contrary to the claims of UCSF.

As we approach the March 19, 2013 deadline for submitting public comments on the Draft Environmental Impact Report for UCSF’s proposed plan to destroy 90% of the forest and its understory on 75% of the 61 acres of the Mount Sutro Reserve, we appeal to our readers to take a few minutes in their busy day to write your own comment (see below for details of where to send comments).

About 200 people came to the community meeting at UCSF last night.  Nearly 60 people spoke; the overwhelming majority spoke in opposition to UCSF’s proposed plans to destroy most of the forest.  Everyone spoke respectfully but with passion about what this forest means to the community.  Many spoke about the loss of trees and habitat where similar projects already have been implemented by the Natural Areas Program and the GGNRA.

Over 1,700 people have signed the petition to save the Sutro Forest. If you haven’t signed yet, please do so here. We’re going to quote a few of the astute and well-informed comments that people have written on the petition in the hope that it will inspire you to write your own comment. (Grammatical edits only.)

Comment #1575:

“Among many other reasons not to hurt this forest- it is healing to people in need of healing at the UCSF hospital. The sight of it sustained me through a difficult labor during which I gazed on it for 13 hours. It is a vibrant, healthy, and sacred forest, and the people who love it will not stand by idly and quietly if it is in harms way”

Scientific studies corroborate this patient’s personal experience. Here is a report of these studies.

Comment #1528:

“Please nooooo!!! do not destroy the habitat for hundreds of creatures. WHY the destruction FOR NOTHING!!! I live in the neighborhood and I am sick and tired to see the city and UCSF cutting down trees and not replacing them.. but only with shrubs and small plants”

This is another San Franciscan who has noticed that the UCSF project is one of many in San Francisco which is destroying trees in order to return the landscape to native grassland and scrub.

Comment #1519:

“The reasons for tree removal are inaccurate. The effort is a waste of resources. The forest is healthy and most importantly serves the needs of the population of the city. UC has indicated its willingness to destroy trees for its own gain, but what the people of SF need is the unique ecosystem that provides wind relief, beauty, and comfort. Native plant restoration is a myopic, militant effort that does not take into consideration the needs of the people who live in SF. This is another effort to waste and destroy for misconceived ideals.”

This San Franciscan understands that the Sutro forest is performing important ecological functions.

Comment #1518:

“The trees in Sutro forest provide immense value to the neighborhood and the city in which we live. It is a wind break, it is a visual stimulus, it is a wonderful place to walk, it is home to a large number of hummingbirds, it isolates a busy hospital from the neighborhood and it provides a tremendous source of ground water to neighboring houses. Save the forest.”

This Sutro neighbor understands that the loss of this forest will harm both the neighborhood and the animals that live in the forest.

Comment #1471:

“Destroying 90% of the trees will destroy the forest – its beauty, its Cloud Forest aspect, and its habitat value. The trees, which sequester tons of carbon, will no longer do so, and instead the dead chipped trees will release carbon dioxide into the atmosphere. PLEASE DO NOT REMOVE THESE TREES!”

This commenter understands that the forest is storing carbon which will be released into the atmosphere as carbon dioxide when the trees are destroyed. Carbon dioxide is the predominant greenhouse gas which is causing climate change.

Comment #1277:

“For environmental reasons please do not cut the forest of Mount Sutro. Risk of landslides (the old forest has intertwined and intergrafted roots that function like a living geo-textile and hold up the mountain, while the exposed rock on Twin Peaks has a rock-slide every year or two); Pesticide drift into our neighborhood, affecting us and our pets (right now, Sutro Forest may be the only pesticide-free wildland in the city; the Natural Areas Program, which controls most of it, uses pesticides regularly) Increased noise (the vegetation – the leaves of the trees and the shrubs in the understory are like soft fabrics absorbing sound) Changes in air quality (trees reduce pollution by trapping particle on their leaves until they’re washed down) Environmental impact – (eucalyptus is the best tree species for sequestering carbon because it grows fast, large, is long-lived, and has dense wood; but felled and mulched trees release this carbon right back into the atmosphere).”

This San Franciscan is aware of the pesticides being used by the Recreation and Park Department’s so-called “Natural Areas Program.” UCSF’s proposed project will use pesticides to prevent the resprouting of the trees that they destroy. Pesticides used by native plant “restorations” are described here. She also understands that trees stabilize steep slopes and reduce air pollution.

Here’s what you can do to help save the Sutro Forest:

• Sign the petition to save the forest. Available here.

• Submit a written public comment by 5 PM, March 19, 2013 to UCSF Environmental Coordinator Diane Wong at or mail to UCSF Campus Planning, Box 0286, San Francisco, CA 94143-0286. Include your full name and address.

• Write to the Board of Regents to ask why a public medical institution is engaging in such a controversial, expensive, and environmentally destructive act. Address: Office of the Secretary and Chief of Staff to the Regents,
1111 Franklin St., 12th Floor, Oakland, CA 94607
 Fax: (510) 987-9224

• Subscribe to the website for ongoing information and analysis.

Ecosystem processes are comparable in native and non-native forests in Hawaii

Native Hawaiian forest. Creative Commons Attribution

Joseph Mascaro is one of the scientists Emma Marris interviewed for her ground-breaking book, Rambunctious Garden.  (1) Marris visited Mascaro on the Big Island of Hawaii, where he was studying the forests, comparing native with “novel” forests, the name given to ecosystems composed of both native and introduced species of plants. 

According to Marris, Mascaro considers Ariel Lugo his mentor.  Lugo is a US Forest Service scientist living and working in Puerto Rico.  He is one of the first scientists to observe and report that non-native forests in Puerto Rico are performing important ecological functions and benefiting native forests by restoring depleted agricultural soils and providing shelter to native seedlings.

Lugo, like many native plant advocates, received his education in ecology at a time when there was deep suspicion of introduced species.  The conventional wisdom was that introduced species were competitors of preferred native species, that they were inferior members of an ecosystem and that they would eventually dominate and replace their native predecessors. 

When Lugo’s team reported that the understory in the non-native forest was so dense that it made the forest impenetrable, he was incredulous.  Slowly, the reality of the non-native forest penetrated the prejudices of his training.  He submitted his findings for publication repeatedly.  After a lengthy debate, his study was finally published in 1992.  He still considers himself an outlier amongst his colleagues in the Forest Service.

Joseph Mascaro is now a Postdoctoral Associate at the Carnegie Institution for Science in Stanford, California.  His study of the novel forests of Hawaiian lowland rain forests has recently been published:  “Novel forests maintain ecosystem processes after the decline of native tree species.” (2)  We will do our layman’s best to report his main findings.

Judging the forest by the functions it performs

The scientific community seems to agree that introduced plant species have resulted in a net increase in species on the Hawaiian Islands:  “Seventy-one vascular plant species are known to have become extinct in Hawaii over the past ~1700 years, while at least 1,090 introduced plant species have become naturalized during this period:  an approximate doubling of its pre-human contact flora.”  (2)

Mascaro’s study asks and answers the question, what are the functional implications of increased diversity due to invasion?  He proposes and tests three hypotheses:

  • Species richness and diversity are greater in novel forests than native forests in lowland Hawaii.
  • Basic measures of ecological functions of novel forests meet or exceed measures in native forests.  He used these basic measures:
    • Aboveground and belowground production of biomass, called productivity
    • Aboveground and belowground storage of carbon
    • Cycling (or turnover) of nitrogen and phosphorous between soil, trees, and leaf litter.
    • Because forest establishment in Hawaii begins on barren lava flows on which there is no available nitrogen and it takes several centuries to accumulate the nitrogen needed by native trees, the disparity between the functioning of novel and native forests are greatest on younger lava flows where novel forests are composed of nitrogen-fixing tree species. 

He reports his findings:  “At local scales, we found that novel forests had significantly higher tree species richness and higher diversity of dominant tree species.  We further found that aboveground biomass, productivity, nutrient turnover (as measured by soil-available and litter-cycled nitrogen and phosphorus) and belowground carbon storage either did not differ significantly or were significantly greater in novel relative to native forests.”  (2)  Our interpretation of this study is that the novel forests of the lowland rain forests of Hawaii maintain basic functioning where native forests are now absent and that the novel forest facilitates the revegetation of barren lava flows by creating fertile soil. 

Barren Hawaiian lava flow. Creative Commons Attribution

He also speculated that “Because large portions of the Earth’s surface are undergoing similar transitions from native to novel ecosystems, our results are likely to be broadly applicable.” (2) It is this conclusion that his findings can be generalized to other locations that brought Joseph Mascaro’s study to our attention. 

Mascaro recently wrote to the Webmaster of the Save Mount Sutro Forest website and sent his study.  He lives in San Francisco and drives over Mt. Sutro daily, on his way to work.  Mascaro told the Save Sutro Webmaster, “I wanted to let you know that your website and effort are much appreciated.  As a practicing ecologist, I find it bewildering that efforts to restore native plant communities (some of which I find very important) would be directed at a diverse, old-growth, functioning ecosystem smack in the middle of one of the largest cities in the country….Cases like Sutro are often emotional and controversial, and while I don’t disparage anyone’s view, I tend to think that great pause must be taken before destroying something that is centuries old.  I hope you will continue your effort.” (quoted with permission)

Mount Sutro Forest. Courtesy Save Mount Sutro Forest

We are grateful to Joseph Mascaro for his research on the novel forests of Hawaii and for expressing his opinion of the value of the forest on Mt. Sutro.  We are also grateful to the Webmaster of Save Sutro Forest for her insightful and articulate defense of the Sutro Forest. 

The evolution of ecology

We began this post with the observation  that scientists have found it difficult to report their findings about novel ecosystems that are not consistent with their educational training.  When we expect to see something, it is often difficult for us to see something that contradicts those expectations.  We commend scientists such as Ariel Lugo for reporting his observations, although they weren’t consistent with his training. 

We are also pleased to report that we have observed, first-hand, a change in the training of university students in ecology.  We attended two sessions of an undergraduate seminar in a local, major university.  That seminar is reading and evaluating Rambunctious GardenThe students were entirely receptive to the revision of traditionally negative judgments of introduced species.  That revision is the main theme of Rambunctious Garden.  These students are the next generation of ecologists.  They are the beginning of a new conventional wisdom about the role of introduced species in our ecosystems. 


(1)    Emma Marris, Rambunctious Garden, Bloomsbury, 2011

(2)    Joseph Mascaro, R. Flint Hughes, Stefan A. Schnitzer, “Novel forests maintain ecosystem processes after the decline of native tree species,” Ecological Monographs, 82(2), 2012, pp. 221-228 by Ecological Society of America