“Restoration” projects in the Bay Area are more destructive than constructive

I began studying the native plant movement and the “restoration” projects it spawned over 20 years ago when I learned about a proposal to change my neighborhood park in San Francisco in ways that were unacceptable to me.  Virtually all the trees in the park were non-native and the original proposal would have destroyed most of them.  The trees provide protection from the wind as well as a visual and sound screen from the dense residential neighborhood.  A treeless park in a windy location is not a comfortable place to visit.

The original plans would have made the park inhospitable to visitors for several other reasons, particularly by reducing recreational access to the park.  The prospect of losing my neighborhood park turned me into an activist.  I eventually learned there were similar plans for most major parks in San Francisco.  My neighborhood organized to prevent the destruction of our park and to some extent we succeeded.  However, we were unable to prevent the city-wide plan from being approved in 2006, after fighting against it for nearly 10 years.

When I  moved to the East Bay, I learned that similar projects are even more destructive than those in San Francisco,  I have spent the last 20 years informing myself and others of these plans, visiting those places, and using whatever public process that was available to oppose the plans.  The following paragraphs are brief descriptions of the projects I have studied for over 20 years.

Tree Destruction Projects in the East Bay

East Bay Municipal Utilities District (EBMUD) is the public utility that supplies our water in the East Bay.  To accomplish that task, EBMUD manages 28,000 acres of watershed land.  Like most open space in the Bay Area, the vegetation on EBMUD’s land is a mix of native and non-native species.  EBMUD destroys non-native trees which it believes to be a fire hazard.  EBMUD uses herbicides to “control” non-native vegetation, but it does not use herbicides on tree stumps to prevent resprouting.  EBMUD reports using 409 gallons of herbicide and 6 gallons of insecticide in 2019.  Of the total amount of herbicide, 338 gallons were glyphosate-based projects.  EBMUD says “minor amounts of rodenticide were applied by contractors.”

The East Bay Regional Park District (EBRPD) approved the “Wildfire Hazard Reduction and Resource Management Plan” and its Environmental Impact Report in 2009.  This plan is removing most eucalyptus, Monterey pine, and acacia from several thousand acres of parkland.  Forests are being thinned from an average density of 600 trees per acre to approximately 60 trees per acre.  These plans are being implemented and funding for completion of the project has been secured.  Herbicides are used to prevent the trees from resprouting and to destroy vegetation deemed “invasive.”

UC Berkeley clear-cut over 18,000 non-native trees from 150 acres in the Berkeley hills in the early 2000s.  UCB applied for a FEMA grant to complete their clear-cutting plans.  The FEMA grant would have clear cut over 50,000 non-native trees from about 300 acres of open space in the Berkeley hills.

Frowning Ridge, UC Berkeley, 2010

In 2016, FEMA cancelled grant funding as a result of a lawsuit and subsequent appeals from UCB were defeated several years later.  In 2019, UCB revised its original plans.  With the exception of clear-cutting ridgelines, the revised plan will thin non-native forests.  Herbicides will be used to prevent the trees from resprouting.

The City of Oakland applied for a FEMA grant in collaboration with UC Berkeley to clear cut non-native trees on over 120 acres in the Oakland hills.  That FEMA grant was cancelled at the same time UC Berkeley lost its grant funding.  Oakland has also revised its plans for “vegetation management” since the FEMA grant was cancelled.  The revised plan will thin non-native forests on over 2,000 acres of parks and open space.  The plan is undergoing environmental review prior to implementation.  Herbicide use to implement the plan is being contested.

Tree Destruction Projects in San Francisco

The Natural Areas Program (now called Natural Resources Division) of the City of San Francisco has destroyed thousands of trees in 32 designated areas of the city’s parks since the program began in 1995.  The management plan for the Natural Areas Program was approved in 2006, after 10 years of opposition.  The plan proposes to destroy an additional 18,500 trees over 15 feet tall and untold numbers of smaller trees that the plan chooses not to define as trees.   Herbicides are used to “control” non-native vegetation and prevent trees from resprouting after they are cut down.

Sutro Forest 2010

University of California at San Francisco (UCSF) began its effort over 20 years ago to destroy most non-native trees on 66 acres of Mount Sutro.  UCSF applied for a FEMA grant to implement those plans based on their claim that the Sutro Forest is a fire hazard.  UCSF withdrew the grant application after FEMA asked for evidence that the forest is a fire hazard.  San Francisco is cool and foggy in the summer, making fires rare and unlikely.

Sutro Forest with resprouts of destroyed trees. November 2019

UCSF’s plans to destroy most trees on Mount Sutro were approved in April 2018.  Many trees on Mount Sutro have been destroyed since the project was approved and more will be destroyed before the project is complete.  UCSF made a commitment to not use pesticides in the Sutro Forest.  Many of the trees that have been destroyed have therefore resprouted.  Unless the resprouts are cut back repeatedly, the forest is likely to regenerate over time.

  Tree Destruction Projects on Federal Lands

The federal government is one of the largest landowners in the Bay Area.  Golden Gate National Recreation Area (75,500 acres), Point Reyes National Seashore (28,800 acres), and Muir Woods National Monument are operated by the National Park Service.  The Presidio in San Francisco is a National Park that is presently controlled by a non-profit trust.  These parks have engaged in extensive tree-removal on the public lands they control.  Information available on their websites does not enable us to quantify the acres or number of trees that have been removed or are planned for removal in the future.  Therefore, we will describe those projects in the broad terms available to us.

There are two main categories of tree-destruction projects on these federal lands.  There are many large-scale “restoration” efforts that have required the removal of all non-native vegetation, including trees.  These attempts to eradicate non-native plants are based on a misguided belief native plants will magically return.  Herbicides are used by National Park Service to destroy non-native vegetation, although specific information is difficult to obtain because NPS is not responsive to inquiries and the federal public records law can take years to respond.

Eradication efforts fail regardless of method used

In “Lessons learned from invasive plant control experiments:  a systematic review and meta-analysis,” scientists analyzed 355 studies of attempts to eradicate non-native plants from 1960 to 2009.  The scientists determined the methods used and the efficacy of those methods.  More than 55% of the projects used herbicides, 34% used mechanical methods (such as mowing, digging, hand-pulling), 24% burned the vegetation, and 19% used all three methods.  The study found that herbicides most effectively reduced “invasive” plant cover, but this did not result in a substantial increase in native species because impacts to native species are greatest when projects involve herbicide application.  Burning projects reduced native coverage and increased non-native coverage. In other words, it doesn’t matter what method is used, eradicating non-native plants does not result in the return of native plants.   We didn’t need a study to tell us this.  We can see the results with our own eyes.

Flammability of plants is unrelated to nativity

The other, larger category of tree-removal projects on these federal lands are the so-called “fuel management projects.”  The flammability of non-native plants and trees is exaggerated in order to justify their destruction.   Native plants are not inherently less flammable than non-native plants.

In fact, native vegetation in California is fire adapted and fire dependent for germination and survival.  The California Native Plant Society recently revised its “Fire Recovery Guide. The Guide now says, “California native plants are not inherently more likely to burn than plants from other areas.”  This statement is the mirror image of what defenders of our urban forest have been saying for 25 years:  “Non-native trees are not inherently more flammable than native trees.”  Both statements are true and they send the same message: flammability is unrelated to the nativity of plants.  “Think instead about characteristics of plants,” according to the CNPS “Fire Recovery Guide.”

There are undoubtedly many other similar projects of which we are unaware.  I report only on projects that I have direct knowledge about and that I have visited.

Why I opposed these projects

The San Francisco Bay Area was nearly treeless before early settlers planted non-native trees.  Non-native trees were planted because they are better adapted to the harsh coastal winds than native trees.  The treeless grassland was grazed by deer and elk and burned by Native Americans to promote the growth of plants they ate and fed the animals they hunted.  Grazing and burning maintained the grassland, preventing natural succession to shrubs and trees.

Native Americans setting grass fire, painting by Frederic Remington, 1908

Modern land use and management policies have suppressed fire and reduced grazing in the Bay Area.  Consequently grasslands are naturally converting to chaparral and scrub.  Although managers of public lands often describe these changes in the landscape as “invasions,” Jon Keeley (Ph.D. biologist, USGS) considers them a natural succession“These changes are commonly referred to as shrub invasion or brush encroachment of grasslands.  Alternatively, this is perhaps best viewed as a natural recolonization of grasslands that have been maintained by millennia of human disturbance.” 

Early settlers planted trees to protect their residential communities and their crops from wind.  The urban forest also provides sound and visual screens around parks that are surrounded by dense residential neighborhoods.  Urban forests are storing carbon that is released as greenhouse gas when they are destroyed. They also reduce air pollution by filtering particulates from the air.

When trees are destroyed, the unshaded ground is quickly colonized by weeds that are then sprayed with herbicide.  Even environmental organizations that support the destruction of non-native trees agree about the results of these projects:

  • The California Native Plant Society predicted the post-project landscape in its written public comment on the Draft Environmental Impact Statement (DEIS) of the FEMA project in the East Bay hills with this rhetorical question: “What mechanism is being instituted by FEMA in this DEIS to guarantee a commitment of money and personnel for management of greatly increased acreages of newly created annual weedy grassland?”
  • The Audubon Society predicted the post-project landscape in its written public comment on the DEIS: “There is no support for the conclusion that native vegetation will return on its own.  This plan may not result in an increase in native trees and plants…Heavy mulching will delay or prevent the growth of native species.”

To summarize:  I am opposed to destroying our urban forests because they perform many important ecological functions, including providing habitat for wildlife.  Furthermore, the herbicides used to destroy the forest and control weeds that thrive in the absence of shade, damage the soil and create unnecessary health hazards to humans and other animals.

Lessons learned from fires in the North Bay

Recent wildfires in the North Bay were devastating.  44 people were killed by the fires and over 8,000 structures were destroyed, including homes and businesses.  We don’t want to portray that fire as anything other than a tragedy.  However, for those with a sincere interest in fire safety, there are many lessons to be learned from that fire.  If people will open their eyes and their minds to the reality of those fires, there are opportunities to reduce fire hazards revealed by those fires.

What burned?

Watching videos of the fires is the best way to answer the question, “What burned?”  Here are two videos of the fires that we found on the internet by doing a search for “videos of wildfires in Napa and Sonoma counties.”  If you weren’t watching the news during the fires, you might start by looking at these videos.  There are many more videos on the internet of those fires.

Here’s what we can see in these videos:

  • The fire front moved rapidly through native conifers and oaks as well as through grassland and chaparral. After watching hours of these videos, we did not see any eucalyptus trees on fire.
  • Many homes burned without igniting the trees and vegetation around them. If the photo was taken while the home was still burning, the vegetation is rarely engaged in the fires.  If the photo was taken after the home burned, much of the vegetation is burned as well.  In other words, the vegetation was ignited by the burning homes, not vice versa.
  • In videos of actively burning homes, the air is filled with burning embers. The source of those embers cannot be determined from the videos.

Nothing in these videos suggests that native vegetation is less flammable than non-native vegetation.  Nothing in these videos suggests that the vegetation is more flammable than the structures that burned. 

CalFire has identified the specific locations where four of the fires originated.  Two are in groves of oak trees and two are in grassland and chaparral.  Photos of those specific locations are available HERE.

UPDATE:  On November 16, 2017, the Bay Area Open Space Council held a symposium about the fires in the North Bay that was billed as a “Community discussion on the impacts of the recent wildfires.”  Bay Nature magazine moderated a panel of experts representing CalFire and 8 managers of public and private open space reserves. 

The Director of Conservation for the Bay Area Open Space Council showed a slide of the vegetation types that burned in the fires.  With the exception of vineyards, only 2% of the burned vegetation was “urban.”  All other vegetation was native grassland, chaparral, and native trees. 

Vegetation that burned in the North Bay files of October 2017. Source: Bay Area Open Space Council

The speaker from CalFire said that we must learn to live with fire.  He suggested that the way to accomplish that goal is with better land use planning, using fire and ember resistant building materials, creating defensible space, and improving the health of our forests. 

The slides of the presenters and an audio recording of their presentations is available  HERE

What role did the weather play in the fire?

All sources of information about the fire reported that strong winds were the biggest factor in the rapid advance of the fire.  The wind was associated with very high temperatures and it came from the east.  This type of wind is called a Diablo Wind in Northern California.  In Southern California it is called Santa Ana Winds.  In the Mediterranean, it is called Mistral Winds.

In coastal Mediterranean climates such as California and the Mediterranean regions of France and Spain, the wind ordinarily comes off of the ocean.  Because the ocean is cooler than the land, the wind is usually a source of moisture and cooler temperatures.  During periods of high summer temperatures, the wind sometimes shifts direction and starts to blow off the hot interior, drying the vegetation and increasing temperatures.

Such winds were also the main cause of the wildfire in the Oakland/Berkeley hills in 1991Jan Null was the lead forecaster for the National Weather Service in the Bay Area in 1991.  He recently said of the 1991 fire:  “At the time a fire starts, the really relevant conditions are the wind speeds, the temperature and the humidity. Again, the humidity goes to the dryness of the fuel. The temperatures also go to the dryness of the fuels and the wind speeds go to what the spread of the fire is. If we’d had that same Oakland Hills fire without any wind, we wouldn’t be talking about it now.”

Most wildfires in California are caused by strong, dry, hot winds.  Everything burns in a wind-driven fire.  Both native and non-native vegetation burns in a wind-driven fire.  Homes in the path of a wind-driven fire are more likely to burn than the vegetation that surrounds the homes because the vegetation contains more moisture.

Why are wildfires becoming more frequent and more intense?

Wildfires are becoming more frequent and more intense all over the world because of climate change.  Temperatures are higher, drought is more frequent, strong winds are more frequent.

Wildfires in the west have become more severe because of increased temperatures and lower humidity at night.  When it doesn’t cool off at night, the trees don’t have an opportunity to regain the moisture they have lost during the high daytime temperatures.  In the past, firefighters could count on wildfires to die down at night.  Now they can’t count on colder nights to make the fires less severe. (2)  Since the fires in the North Bay started in the middle of the night and did the most damage that first night, this observation about warmer nights is particularly relevant to those fires.

Deforestation is the second greatest source of the greenhouse gases causing climate change Every healthy tree we destroy releases its stored carbon as it decomposes.  Every tree that dies of drought releases its carbon as it decomposes.  Every tree that burns in a wildfire releases its carbon as it burns.

What role did power lines play in the fire?

The investigation of the recent wildfires in the North Bay is not complete, but early indications suggest that power lines probably ignited some of the fires.  Some power poles fell over in the strong winds, causing the power lines to break and spark ignitions.  Some trees were blown into the power lines, causing them to break or spark.

California State law requires that trees be pruned at least 4 feet from the power lines.  Although PG&E says they are inspecting thousands of miles of power lines to identify potential interference with trees, these inspections are apparently not adequate.  After the fires started, PG&E claimed they had removed 236,000 “dead and dying” trees and “destroyed or pruned” 1.2 million healthy trees in 2016.  These destroyed trees contribute to climate change.

California State law also requires that power poles are capable of withstanding winds of a certain velocity.  However, power poles fell over during the recent fires when wind speeds were below that standard set by State law.

Apparently PG&E’s efforts to inspect and maintain power lines were inadequate and State laws intended to ensure the safety of power lines are not being enforced.

Did Sudden Oak Death contribute to the fire?

Sudden Oak Death (SOD) killed 5 million oak trees in California from 1994 to 2016, when that number was reported by a study.  The study also said that the SOD epidemic could not be stopped and would eventually kill all oaks in California.  More recent estimates are that 5 to 10 million oaks have been killed by SOD. (2)

SOD is caused by a pathogen that is spread by rain and wind.  We had a great deal of rain in 2016 and 2017, which has greatly increased the spread of SOD.  In the past, SOD has been mostly confined to wildlands.  Now it is found in many urban areas, including San Francisco and the East Bay.  In the most recent SOD survey done in spring 2017, new infections were found on the UC Berkeley campus, the UC arboretum, and the San Francisco Presidio. (2)

The scientist at UC Berkeley who conducts the annual survey of SOD infections reports that “A dramatic increase this year in the number of oaks, manzanita and native plants infected by the tree-killing disease known as sudden oak death likely helped spread the massive fires that raged through the North Bay…” (3)

Dead trees are more flammable than living trees because living trees contain more moisture.  In addition to more than 5 million dead oak trees in California, 102 million native conifer trees in the Sierra Nevada foothills were killed by drought, warming temperatures and native beetle infestations during the drought years. All of these trees are native to California.  This is another indication that native trees are not less flammable than living non-native trees.

The ranges of native plants and animals are changing because of climate change.  They must move to find the climate conditions to which they are adapted.  Native plant “restorations” that attempt to reintroduce plants where they existed 250 years ago, prior to the arrival of Europeans, do not take into consideration that the plants may no longer be adapted to those locations.  That’s why many “restorations” are not successful.

If you haven’t seen the Sutro Forest, you should do so soon. The plans are to destroy about 50% of the trees and most of the understory.

Native plant advocates have their heads in the sand about Sudden Oak Death.  The recently published Environmental Impact Report for San Francisco’s Sutro Forest announced UCSF’s intention to destroy about 50% of the non-native trees on Mount Sutro and replace some of them with native trees, including oaks and bays.  Bays are the vector of the pathogen causing SOD.  The EIR said NOTHING about Sudden Oak Death, nor did it acknowledge the existence of the disease in Golden Gate Park and the arboretum, less than a mile away from Mount Sutro.  What’s the point of destroying healthy trees and replacing them with trees that are likely to die in the near future?

Where to go from here?

We are not powerless against bad decisions of public utilities and the forces of nature.  There are things we can do to address these causes of wildfires in California:

  • We must address the causes of climate change. We must stop destroying healthy trees and we must plant more trees.  We must choose species of trees that have a future in the changed climate.  The trees must be adapted to current and anticipated climate conditions.  We must quit destroying trees simply because they are not native.  Non-native trees are not more flammable than native trees and many are better adapted to current climate conditions.
  • We must regulate our public utilities and demand that regulations be enforced. The Public Utilities Commission initiated an effort to improve the safety of power lines in 2007, after destructive wildfires. The utility companies have been actively dragging their feet to prevent new regulations because they would increase costs, despite the fact that they would improve safety.
  • Improved regulation of utilities should minimize the need to destroy healthy trees, by undergrounding power lines in the most high-risk areas, improving insulation of the wires, replacing wooden power poles with metal and/or concrete poles, installing sensors that identify breaks in the power lines, etc.

Demonizing non-native trees is preventing us from addressing the causes of climate change and the closely related issue of increasing frequency and intensity of wildfires.  Let’s open our eyes and our minds to the reality of wildfires in California and develop the policies that will reduce fire hazards.

(1) The Detwiler Fire is active at night, and a scientist says that’s relatively new,” Fresno Bee, July 22, 2017

(2) “Disease killing oaks spreads,” East Bay Times, October 24, 2017

(3) “Disease in trees pointed at in fires,” San Francisco Chronicle, October 20, 2017

Destroying trees causes erosion and landslide risk

We are republishing with permission a post from the Save Mount Sutro Forest blog.  At the end of the Save Sutro post we add an example of erosion in the East Bay caused by tree removals by UC Berkeley. 


When UCSF  (or SF Recreation and Parks Department) discusses “Safety” in the forests on Mt Sutro and Mt Davidson,  they generally focus on fire hazard (relatively low in these damp cloud forests), or on the risk of being hit by a falling tree (about half the risk of being hit by lightning). Tree removal could actually increase both those risks, by drying out the forest and by increasing windthrow – the risk of  the remaining trees being blown over.

But what we want to talk about in this post is landslide risk.

Two weeks ago, a horrible mudslide in Washington State engulfed homes and took lives. Some scientists think logging trees in the area contributed to the tragedy. This has implications for Sutro Forest, which grows on a steep hill – and also for the other San Francisco forest, Mount Davidson. Tree removal, ongoing and planned, could destabilize the mountainsides.

Mount Sutro forest viewed from southeast (Twin Peaks)LOGGING AND LANDSLIDES

On March 22, 2014, a huge landslide destroyed the small Washington community of Oso. Rain was of course a factor, as was erosion at the base of the slope. But it’s probable that tree-cutting above the slide area was an important factor too. An article in the Seattle Times quotes a report from Lee Benda, a University of Washington geologist. It said tree removal could increase soil water “on the order of 20 to 35 percent” — and that the impact could last 16-27 years, until new trees matured. Benda looked at past slides on the hill and found they occurred within five to 10 years of harvests [i.e. felling trees for timber].

There had been red flags before. The area was second growth forest, grown back from logging in the 1920s/30s. Over 300 acres were again logged in the late 1980s.

  • The first time regulators tried to stop logging on the hill was in 1988. But the owner of the timber successfully argued that measures could be taken to mitigate the risk. Eventually, the state only blocked it from logging some 48 acres, and the owners  gave in on that.
  • In 2004, new owners applied to cut 15 acres; when the Department of Natural Resources (DNR) objected, they halved the area and re-located the cut. DNR gave approval, subject to no work during heavy rain and for a day afterward. The tree-cutting finished in August 2005.
  • In January 2006, there was a major landslide 600 feet from the cut zone. The state built a log wall to shore up the slope.
  • The owners continued logging. In 2009, they removed 20% of the trees. In 2011, they removed another 15%. In 2014, the hillside collapsed.

The regulators were aware of the risk; they thought they were mitigating it with their restrictions and reaching a compromise with the owners. But it wasn’t enough. Destabilizing the mountainside is a long-term thing; the effects can show up in months, but it’s more likely to take years.


We know our hills are prone to slides. Here’s a geological map of Mt Sutro and surrounding areas. The blue zones show where there’s a potential landslide risk:

Blue areas show "potential for permanent ground displacements..."
Blue areas show “potential for permanent ground displacements…”

This next map is from a UCSF document. The pink areas and wiggly arrows indicate landslide risk. The double-arrows show where actual landslides seem to have occurred in the past.

Pink areas and wiggly arrows show landslide risk; double line arrows show past landslides.
Pink areas and wiggly arrows show landslide risk; double line arrows show past landslides.

Landslide under blue tarp. South Ridge at top left.
Landslide under blue tarp. South Ridge at top left.

This slope in the Forest Knolls neighborhood was covered in a blue tarp for months after the slope became destabilized by tree removal…

This other blue tarp is on the hillside above Medical Center Way. It was installed soon after some extensive work on the trail in that area, with undergrowth being cleared and trails realigned. When we enquired why it was there, UCSF said there had been some rock slides, and this was a temporary solution.

This photograph was taken in March 2013. A year later, the blue tarp is still there.

blue tarp above Medical Center WayFor more evidence, there’s the ongoing situation in Twin Peaks, where erosion and rockfalls in rainy weather are ongoing. There, it matters less, because it’s not falling on homes. Landslides on Mt Sutro or Mt Davidson have the potential to damage homes.



While it’s possible that a slide could happen within months of the tree-felling, it could also happen 6-8 years later as the root systems rot away. It could happen in any year until the trees grow back and conditions are right for water-logging. On that fateful Washington slope, the average was 5-10 years. No one wants to find out the average for San Francisco slopes.

We ask the land managers for these forests to stop removing trees and large shrubs that have successfully stabilized our hillsides for decades.


Addendum:  About 10 years ago, UC Berkeley removed about 18,000 trees on 150 acres of its property.  This is a photo of erosion that resulted from that tree removal on Grizzly Peak Blvd close to the intersection with Claremont Ave.  This erosion has been getting steadily worse for at least 5 years.  The only remediation has been plastic and sandbags, which are clearly not capable of preventing further erosion. 

Grizzly Peak Blvd, south of Claremont Ave.  Berkeley, California
Grizzly Peak Blvd, south of Claremont Ave. Berkeley, California

California Invasive Plant Council fails to make the case that eucalyptus is allelopathic

In this post we will continue to critique the assessment of the California Invasive Plant Council (Cal-IPC) that Blue Gum eucalyptus (Eucalyptus globulus) is invasive.  One of the arguments that Cal-IPC used to reach this conclusion is that chemicals in the leaves of eucalyptus suppress the germination of native plant species:  “[E. globulus] inhibits germination and growth of native plant species.”   This property is called allelopathy.

Many plants, both native and non-native have such allelopathic properties.  Therefore it is important both to determine if eucalyptus has such properties, and to compare eucalyptus to native tree species to determine if suppression of germination of competing species is any more likely under eucalyptus than native tree species.  One of the references provided by Cal-IPC compares germination success of three native plant species using both eucalyptus leaves and oak leaves:  “The Effect of Eucalyptus and Oak Leaf Extracts on California Native Plants” (1)

This unpublished master’s degree thesis does not prove that eucalyptus leaf extracts inhibit growth of native plants.  The study uses two different methods to test the hypothesis that eucalyptus leaf extracts inhibit growth of native plants.

In the first method, the seeds of three native species (two bunch grasses and a perennial forb) were germinated in petri dishes in sand soaked with a solution of the masticated leaves of eucalyptus and oak.  Two of the species of seeds grew shorter roots in the eucalyptus solution than in the oak solution.  The third species of seed grew longer roots in the eucalyptus solution than in the oak solution.  The percent of germination was lower in the eucalyptus solution than in the oak solution for two of three of the species of seeds and the same in the third species of seed.

The second method used by this study was to test germination success in the soil of eucalyptus compared to oak soil.  No significant difference was found in germination success when seeds were planted in the soil:

“The Eucalyptus soil treatment did not result in germination inhibition relative to the control which suggests that allelochemicals present in the leaves are reduced or absent in the soil.”  (1)

Since natural germination occurs in the soil rather than in petri dishes soaked in concentrated solutions, this study does not substantiate the statement that E. globulus “inhibits germination and growth of native species.”

Using our eyes to test the theory

We don’t doubt that the leaves of eucalyptus contain chemicals.  But the leaves of other trees do as well.  The question is not whether or not the leaves of trees contain chemicals, but rather do they prevent the germination and growth of other species of plants?  The fact is no study has proved that the chemicals in the leaves of eucalyptus are more likely to prevent the survival of native species of plants than any other tree species, whether native or non-native.  We can see with our own eyes that eucalyptus forests often have a thriving understory of both native and non-native plants.  Here are just a few examples of local eucalyptus forests that have such an understory:

The management plan for San Francisco’s Natural Areas Program describes the eucalyptus forest on Mount Davidson as follows:

“Although the overstory is dominated by eucalyptus, when all species were considered within the urban forest at Mount Davidson (point data), native species accounted for 36 percent of the understory cover and 21 out of 50 species were native…Pacific reed grass (Calamagrostis nutkaensis) does not have a state or federal special-status rating, but San Francisco is at the southern edge of this species’ range. This species can be found in several locations on Mount Davidson”

Native Pacific reed grass under girdled eucalyptus tree on Mount Davidson
Native Pacific reed grass under girdled eucalyptus tree on Mount Davidson

The 2011 “Albany Hill Creekside Master Plan” describes the understory of the eucalyptus forest on Albany Hill as follows:

“The eastern portion of the eucalyptus forest has a [native] toyon understory as identified in 1991.  The toyon appears to be a wider band than shown in 1991 and covers approximately 2.0 acres…It was noted in a 1972 article in the California Native Plant Society publication Fremontia that the toyon has been introduced by either man or birds.  Native species [in the eucalyptus forest] include toyon, coast live oak, coyote brush, blue wild rye grass, and poison oak.”  

Native toyon under eucalyptus on Albany Hill
Native toyon under eucalyptus on Albany Hill

Finally, the understory of the dense eucalyptus forest on Mount Sutro is the richest understory we have personally witnessed.  Its understory is composed of both native (most notably elderberry) and non-native species.

The lush, green understory on Mount Sutro.  Courtesy Save Sutro Forest.
The lush, green understory on Mount Sutro. Courtesy Save Sutro Forest.

We give the last word on the scientific question of the allelopathic properties of eucalyptus to R.G. Florence of the Department of Forestry at The Australian National University.  An Australian scientist is not under the same pressure to find a negative story to tell about eucalyptus.  Professor Florence reports that a world survey of 3,000 articles about allelopathy found “…that the phenomenon of direct chemical interaction in natural communities, in the face of natural selection pressure, must be regarded as rare.”  And further, “While [allelopathy] is an attractive concept, there is no certainty that this occurs to any appreciable extent in nature.” (2)  These observations are certainly consistent with the reality of the eucalyptus forest in the San Francisco Bay Area, where an understory of both native and non-native plants is often found.

If not allelopathy, then what suppresses understory growth?

We have hiked as often in oak woodland in California as we have eucalyptus forests.  We find the understory in the oak woodland as varied as any eucalyptus forest.  Sometimes we don’t find much understory in either type of forest.  A redwood forest has the sparsest understory of any of these three tree species.

What these forest types have in common is that there is a layer of leaf litter under them that suppresses germination and growth of other plants because it forms a physical barrier to the soil.  And the limited sunlight on the floor of both forests is surely a factor in suppressing the development of an understory.  When an understory persists through the limiting factors of low light and heavy leaf mulch, there are obviously mitigating factors such as more moisture, better soil, and other resources that understory plants need.  Furthermore, some species of native plants seem to be suited to conditions in the eucalyptus forest.

The leaves of eucalyptus contain chemicals–as do the leaves of all plants– but if they do not prevent the growth of an understory or they are not any more likely to suppress the growth of competing plants than chemicals in native tree species, this is not a legitimate argument against eucalyptus.  Cal-IPC has not provided any scientific justification for indicting eucalyptus based on its allelopathic properties.


(1)    Kam Watson, “The Effect of Eucalyptus and Oak Leaf Extracts on California Native Plants,” 2000.

(1)    R.G. Florence, Ecology and Silviculture of the Eucalypt Forest, CSIRO, 1992?, pgs 71 & 103

Scientists critique UCSF’s plans for Mount Sutro and native plant advocates react

Nature is considered one of the top journals in science globally.  So, we were very excited about the article they published in their September 2013 edition about Mount Sutro. (1) The article starts with every bogus claim UCSF makes to justify the destruction of the forest, i.e., that it is flammable, that it is diseased, that it will store more carbon when most of it is destroyed.  We have responded to those claims many times on Million Trees, so we won’t repeat those arguments here.  (We have provided links to our articles about each of these issues, so you can read them if you wish by clicking on each issue.)

Sutro forest before recent tree removals.  Courtesy Save Sutro
Sutro forest before recent tree removals. Courtesy Save Sutro

After faithfully repeating UCSF’s storyline, Nature turns to the opposite side of this debate, starting with the welcome introduction of critics of the Sutro project as “environmentalists and ecologists” for whom “a hardline devotion to preserving native ecosystems is giving way to a more post-modern idea of what constitutes a natural landscape.”  The author of the Nature article interviewed scientists who agree with this new perspective:

  • “’Mount Sutro is part of a larger story,’ says Richard Hobbs, an ecolo­gist at the University of Western Australia in Crawley. ‘What some people see as a weed-filled blot on the landscape, others see as something extremely valuable, worthy of managing in its own right. People are increasingly moving away from the belief that a native ecosystem is always best….There is a lot of tension about how to deal with situations like these right now,’ he says. ‘With so much non-native habitat, the old views — that everything must be natural — no longer apply.’”
  • “In the early 1990s, Patricia Kennedy of Oregon State University in Corvallis helped to develop management guidelines for northern goshawks. She found that the raptors do not strictly need old-growth forests; land used for timber harvesting can work, too. She says that, at the time, accept­ing the idea felt like a move to the ‘dark side’. ‘The whole culture in wildlife biology and conservation circles has been that you can’t approximate Mother Nature,’ she says.  But those ideas are changing today, with altered ecosystems such as Mount Sutro’s providing a case in point.”
  • Joe Mascaro, an ecologist at Stanford University in California [2] who has been publicly critical of UCSF’s management plans, says that Mount Sutro has long since given way to a completely new ecosystem. ‘Restoring it to an original state would be borderline impossible, so why stop the succession that is already in place?’”
  • “Resistance to such a heretical idea runs deep among ecologists, but growing num­bers are embracing altered ecosystems in the name of pragmatism. ‘You can reach more win–win situations if you don’t insist on purity,’ says Katharine Suding, an ecologist at the University of Califor­nia, Berkeley, who specializes in restoring human-affected areas. ‘It doesn’t have to be a natural versus non-natural dichotomy.’”

Same section of Sutro forest after tree and understory removal at the end of August 2013.  Courtesy Save Sutro
Same section of Sutro forest after tree and understory removal at the end of August 2013. Courtesy Save Sutro

The reaction of native plant advocates

As pleased as we were to hear from the international scientific community, we didn’t fully appreciate the significance of the article until we read the reaction of native plant advocates in Jake Sigg’s Nature News:

“On Sep 15, 2013, at 4:13 PM, Peter Brastow wrote (re NYT editorial on Mt Sutro):
‘Yes, and recall that the NYT article linked to an awful piece in Nature. I see this as PhD Academicians liking the sound of their own voice, and certain members of the media who, likewise, don’t actually know anything about on-the-ground land management. To boot, their arguments support continued environmental destruction around the world, whether for palm plantations, bio-fuel production, cattle grazing, suburban development, you name it. Do you think these same people advocate letting the Amazon rainforest be clearcut from end to end?’” 
(Jake Sigg’s Nature News, September 21, 2013)

It seems that native plant advocates disliked the Nature article as much as we liked it. This comment from a prominent native plant advocate in San Francisco is more evidence of the growing gap between restorationists and the scientists of invasion biology who spawned the native plant movement.  We have noted before the inevitable tension between theoretical science and its practical application and in the case of ecological restoration in the Bay Area, it is becoming more and more distant from its scientific underpinnings.

What is San Francisco’s Biodiversity Program?

You might think that the loss of scientific support for the projects in the Bay Area which are attempting to convert non-native to native landscapes would weaken the local native plant movement.  You would be mistaken.  Peter Brastow, the author of this comment, is employed by the City of San Francisco as the Director of Biodiversity in the Department of the Environment.  The creation of this program and the selection of Mr. Brastow as its first director suggest official endorsement of these projects and imply their expansion beyond their present footprint.  This is the mission of San Francisco’s Biodiversity Program according to the Department of Environment’s website:

“The mission of the Biodiversity Program is to conserve the biodiversity, habitats and ecological integrity of San Francisco’s natural environment, toward a comprehensive watershed- and ecosystem-based natural resources management, stewardship and education program.

Our approach is to advance collaboration and coordination for biodiversity policy development and interagency conservation planning and management.

San Francisco’s indigenous biodiversity exists among diverse open lands and habitats in a complex urban geography of parklands, natural areas, urban forests, community gardens and backyards. The scope of the program includes protection of all of the City’s biological diversity and natural lands, and for strategic integration of nature conservation best practices into planning, implementation and education for the built environment.

We hope to raise the bar on integrating considerations for nature and biodiversity into the operations of every City Department as well as into every aspect of city life, including making significant increases in public and City employee awareness.”

Our interpretation of this vague, abstract description is that the goal of San Francisco’s Biodiversity Program is to extend the native plant restorations of the Recreation and Park Department’s Natural Areas Program to all city departments and all city-owned open space, perhaps even to your backyard.

Since we think the Natural Areas Program has been a miserable failure, with respect to successfully converting naturalized non-native landscapes to native plant gardens, we have serious doubts about expanding the program to the entire city.  And since the Natural Areas Program is using a great deal of pesticide, destroying many healthy trees, and plans to destroy thousands more, we are not enthusiastic about subjecting more public land to such damage.

We are equally alarmed by the dismissal of scientists by the Director of Biodiversity, Peter Brastow, as people who like to hear themselves talk.  This suggests that the Director of Biodiversity isn’t listening to the rapidly changing science of invasion biology.  You might wonder what Peter Brastow’s qualifications are to enable him to dismiss academic scientists as a resource for the application of invasion biology to native plant restorations.  You can visit his resume on the internet to satisfy that curiosity.


For the record, we are not supporters of the “environmental destruction” of which Mr. Brastow accuses the scientists who are quoted in the Nature article.  We do not “advocate letting the Amazon rainforest be clearcut from end to end,” as Mr. Brastow claims.  We are confident that no one else with whom we collaborate does so either.  The only clearcutting we have witnessed first-hand was done in response to the demands of native plant advocates; these projects have already destroyed 18,000 non-native trees in the East Bay hills and are determined to clearcut about 80,000 more.  This looks like a classic case of “pot-calls-kettle-black.”


(1)    Danielle Venton, “Forest management plans in a tangle,” Nature, September 2013, Vol. 501

(2)    When Mr. Mascaro was interviewed, he was at the Carnegie Institute of Research in Stanford, California.

Wind and Trees

The public comment period for the Draft Environmental Impact Report (DEIR) for UCSF’s plans to destroy 90% of the forest and its understory on 46 acres of the Mount Sutro Open Space Reserve ended on March 19, 2013.  We studied that document carefully to evaluate its accuracy and form our own opinion of the impact this project will have on the environment.  Because Mount Sutro is a very windy environment, we paid particular attention to the influence of the wind for the consequences of UCSF’s proposed plans to destroy most of the forest.  In the process, we learned something about the interaction between wind and trees that we would like to share with our readers.

The wind on Mount Sutro

Mount Sutro is a 900+ foot hill that is directly exposed to the wind from the west, coming off the ocean.  Steep slopes accelerate the wind as it moves uphill.  On the leeward side of a steep hill the wind breaks into turbulent gusts.  This is an oversimplification of the movement of wind over a hill because in a complex topography such as Mount Sutro, the movement of the wind is as complex as the topography.  For example, Mount Sutro is penetrated by a number of steep canyons that funnel the wind as it moves uphill.   

Anyone who has visited the UCSF campus on the top of the hill knows that it is a cold, miserable, windy place much of time.  But if you walk in the dense forest on Mount Sutro, you are often unaware of the wind because the trees are shielding you from the wind. 

UCSF plans to destroy its windbreak by reducing the density of the forest from 740 per trees acre to only about 15-50 trees per acre.  The campus and the neighborhoods on the leeward side of Mount Sutro are going to be subjected to a great deal more wind.  They will also experience more fog which is now being “caught” by the tall trees and condensed as moisture to the forest floor.  That fog is now going to flow freely from the ocean to the neighborhoods on the leeward side of Mount Sutro.

The consequences for the few trees that remain

UCSF would like the public to believe that it doesn’t intend to destroy the entire forest.  However, that is the likely consequence of destroying 90% of the trees on 46 acres because trees develop their defenses against the wind in a specific environment with a specific amount of wind and they often fail when they are exposed to more wind than they are adapted to.

Wndthrow caused by adjacent clearcut, Britain.  Creative Commons
Wndthrow caused by adjacent clearcut, Britain. Creative Commons

UCSF’s own written plans for this project acknowledge that thinning the forest will increase the likelihood of the remaining trees failing:  “Individual trees that suddenly become more exposed to high winds are also more likely to fall.  For this reason, any thinning of the forest that is considered must not be so extensive that it will subject remaining trees to increased windfall.”  (1, page 15) Ignoring its own advice, UCSF proposes to destroy over 90% of the trees on 46 acres of the reserve.

The DEIR also acknowledges that the trees remaining after the forest is thinned will be vulnerable to windthrow for some unknown period of time during which they adjust to the changed environment.  The DEIR suggests that it is possible to mitigate for this potential for windthrow by monitoring the remaining trees to identify potential hazards.  In other words, the DEIR claims that it is possible to accurately identify trees that might fall before they fall. 

This is a fiction.  If it were indeed possible to accurately predict that a tree will fall, we wouldn’t read reports of thousands of trees falling all over the country every year.  Over 5,400 tree failures were reported to the University of California’s “California Tree Failure Report Program” in 2012.  Since reporting is voluntary, we assume that is an underestimate of all tree failures in California in 2012.  (Oaks (Quercus) were the most frequently reported genus to have failed in 2012:  22.7% of 5,415 reported tree failures were oaks.   Failures of eucalyptus were nearly half that (11.90%).)  

Any reputable arborist will tell you that evaluation of trees for potential hazards is an art, not a science.  That is, it is a subjective judgment and this is reflected in the wide numerical range used to rate trees for potential hazards.  When an arborist agrees to a contract to conduct such an evaluation, he/she usually does so with a liability caveat, making it clear that he/she cannot accept legal responsibility for trees that fail which haven’t been identified as hazardous by their evaluation. 

For these reasons, the mitigation offered by the DEIR looks like a trap.  If the evaluation is applied conservatively, the ultimate destruction of the entire forest seems likely.  In other words, the few trees that remain will be declared hazardous and destroyed.  Since those who demand this project have made it perfectly clear that they want the entire forest destroyed, that seems the likely scenario.  If, on the other hand, the evaluation is not applied conservatively, unpredicted tree failures are likely.  In either case, the ultimate outcome is a forest with fewer trees than projected by the DEIR. 

In a consultation with Professor Joseph McBride of UC Berkeley, we were provided with two specific examples to illustrate this trap.  Professor McBride evaluated two extreme windthrow events in the San Francisco Presidio and Sea Ranch.  This study is cited by the Sutro DEIR. (2)  Professor McBride told us that of the 6,000 trees that failed in the Presidio in an extreme weather event in 1993, most would not have been identified in advance as being vulnerable to windthrow.  Healthy, structurally sound trees fail in extreme weather events.  Conversely Professor McBride told us of an evaluation of all trees on the Berkeley campus in 1976 that judged about 3% of the trees as hazardous for which removal was recommended.  Shortly after the evaluation was conducted, UC went through a period of budgetary constraints (much like the one UC is having presently) which prevented the removal of the trees judged to be hazardous.  Over 35 years later, about 80% of those trees are still standing.  In other words, trees judged healthy by professional arborists sometimes fail and trees judged hazardous often do not fail. 

On April 7, 2013, the Bay Area experienced high winds that demonstrated both our windy environment and the consequences for our trees.  Winds of 75 miles per hour were recorded in San Francisco.  At the San Francisco airport, on the eastern (leeward) side of the City, winds of 35 miles per hour or more were recorded for 21 consecutive hours, an unusually sustained high wind.  Both the strength of the wind and its duration caused many trees to fail.  In San Francisco, 75 fallen trees were reported to the Department of Public Works.  Here’s a brief article in the San Francisco Chronicle about this destructive wind, including photos of some of the many trees that fell.

 How wind affects the health of trees

The DEIR would like the public to believe that the thinned forest will be capable of growing sufficiently to compensate for the loss of the existing capability to sequester carbon and recoup the loss of much of the existing stored carbon because the remaining trees will be released from competition.  One of the reasons why this is wishful thinking is that the trees that remain will be subjected to a great deal more wind and that wind is going to reduce the trees’ ability to grow:

“As the magnitude of the stress (windspeed) increases, so do the resulting strains, resulting in a cascade of physiological strain responses.  The physiological responses range from rapid changes in transpiration and photosynthesis at the foliar level, to reduced translocation, callose formation and ethylene production in the phloem and cambial zone.  Long-term developmental and structural changes occur in canopy architecture and biomechnical properties of the xylem. “(3)

This same article explains that the canopy of a tree that is subjected to a great deal of wind tends to be narrower than one subjected to less wind and its leaves are smaller, which is one of the reasons why photosynthesis and transpiration are suppressed in a windy environment.

We turn to Joe McBride’s wind study of the Presidio (4) for a specific, local example that illustrates these general principles.  This is what Professor McBride observed at the Presidio: 

“Wind at the Presidio affects tree growth, form, and mortality.  Exposure to winds in excess of 5 mph usually results in the closure of the stomata to prevent the desiccation of the foliage (Kozlowski and Palhardy, 1997) Photosynthesis is thereby stopped during periods of moderate to high wind exposure resulting in a reduction in tree growth…Eucalyptus showed the greatest reduction in growth with trees at the windward edge being only 46 percent as tall as trees on the leeward side.” (4, page 6)

The plans to destroy 90% of the trees on 46 acres of Mount Sutro will subject the few trees that remain to a great deal more wind.  The growth of the few trees that remain will be significantly retarded by the wind.  The claim of the DEIR that those trees will grow significantly larger when released from competition from their neighbors is fallacious because it does not take into account that the trees will be subjected to significantly more wind.

 Why, oh why?

We cannot imagine why UCSF wants to destroy most of its forest.  These are a few of the most mysterious questions that we cannot answer:

  • Why does UCSF want to subject its students, its patients, and its staff to more wind?  Why does it want to subject its neighbors to more wind and fog? 
  • Does UCSF really believe that destroying 90% of the forest on 46 acres of the Sutro Reserve will not result in the destruction of the entire forest? 
  • Does UCSF really believe that the few trees that remain will grow so large and so fast as to compensate for the loss of the ability of the forest to sequester carbon?

We are speaking of a world-class scientific institution.  Could it really be so ignorant?  Or is there some ulterior motive that is not visible to us?  Conspiracy theories abound in the public comments that have been submitted.  We cannot verify any of those theories, so we won’t repeat them.  We actually prefer to believe the latter explanation, because the thought of such an important scientific institution being so ignorant of scientific facts is too painful to contemplate.


(1)    “Mount Sutro Open Space Reserve Management Plan,” EDAW (consultant to UCSF), 2001

(2)    McBride and Leffingwell, “Assessing windthrow potential in urban forests of coastal California,” Society for American Forests Newsletter, 2006

(3)    F. W. Telewski, “Wind induced physiological and development responses in trees,” in Wind and Trees, edited by MP Coutts and J Grace, Cambridge University Press, 1995

(4)    Joe R. McBride, “Presidio of San Francisco, Wind Study, First Phase,”  circa 2002

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 EIR@planning.ucsf.edu 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 SaveSutro.com for ongoing information and analysis.

Message to UCSF: Do the math!!

UCSF has sent an email to its neighbors about its plans for the Sutro forest in which they say, “Contrary to rumors being circulated, there is no plan to cut down 30,000 trees in the Mount Sutro Open Space Reserve, and it is unfortunate that this misinformation continues to spread.”

Our response is, Do the math!!

The Draft Environmental Impact Report (DEIR) claims that the thinned forest will have 62 trees per acre. (DEIR Appendix F) The DEIR arrives at this figure by assuming that each tree will occupy a circle with a radius of 15’. In fact, it is not possible to pack circles into another geometric space, whether it is a bigger circle, a rectangle or a square without wasting space. Therefore, this calculation arrives at a bogus answer which is larger than is physically possible.

We have calculated the number of trees remaining in the thinned forest based on the number of squares in an acre that are 30’ X 30’. Such calculations of tree density are found in books regarding arboriculture, which corroborates that we are using a standard calculation used by the timber industry and the DEIR is not. (1)


43560/900 = trees per acre if 30 feet apart (the proposed plan)


43560/3600 = trees per acre if 60 feet apart (the proposed plan)


Total number of trees existing now on 61 acres (according to UCSF)


46 acres X 740 trees/acre = Number of trees existing in project area


44 acres X 48 trees/acre = thinned forest with 30’ spacing


2 acres (Demo Area #4) X 12 trees/acre = thinned forest with 60’ spacing


Existing Trees – Thinned Forest = Trees Removed in Project Area


Trees Removed/Existing Trees in total forest = Percent of Trees Removed in Total Forest

If UCSF wishes to reduce the number of trees that will be removed by the proposed plan, it can do so by reducing the spacing between the trees or the number of acres to be “thinned.” All other numbers used to arrive at an estimated number of tree removals are straight-forward mathematical calculations based on the information provided by UCSF.

UCSF would be wise to read the DEIR for its project, which says, “Under full-implementation or worst-case implementation of management activities under the proposed project, approximately 60% of all existing trees, including large and small trees, could be removed.” UCSF reports that there are 45,000 trees in the Mount Sutro Reserve presently. Sixty-percent of 45,000 is 27,000 trees. We think UCSF’s estimate of tree removals is just a few thousand trees less than what is actually planned. What are we quibbling about?

Once again, we invite UCSF to revise its proposed project to reduce the number of trees that will be removed.

(1) Ecology and Silviculture of Eucalypt Forests, R.G. Florence, CSIRO, Australia

Plans to destroy over 30,000 trees on Mount Sutro

We are reprinting with permission Save Sutro’s announcement of the Draft Environmental Impact Report for the project to destroy over 30,000 trees on Mount Sutro in San Francisco.

Here are the things you can do to participate in the effort to save this beautiful forest:

  • Sign the petition to save the forest.  Available here.
  • Attend and speak at a UCSF hearing about the project:  Monday, February 25, 2013, 7 pm, Millberry Union Conference Center, 500 Parnassus Ave, Golden Gate Room                                                                             
  • Submit a written public comment by 5 PM, March 19, 2013 to UCSF Environmental Coordinator Diane Wong at EIR@planning.ucsf.edu 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 SaveSutro.com for ongoing information and analysis.


Mount Sutro Forest has approximately 45,000 trees in the 61 acres belonging to UCSF, and designated as an open space reserve. This dense forest, with an estimated 740 trees per acre, a sub-canopy of acacia, an understory of blackberry and nearly a hundred other plant species, is functionally a cloud forest. All summer long, it gets its moisture from the fog, and the dense greenery holds it in. Where it isn’t disturbed, it’s a lush beautiful forest, providing habitat for birds and animals, and a wonderful sense of seclusion from urban sounds and sights.

Mount sutro forest greenery


UCSF now has published a Draft Environmental Impact Report (DEIR) on a project to remove over 90% of the trees on three-quarters of the area. Only 15 acres – on the steep western edge of the forest – will remain as they are. Tree-felling could start as early as Fall 2013.

[Edited to Add:

Here is the PDF of the DEIR. Mount_Sutro_EIR_1-16-13_with_Appendices

Comments were due on March 4th, but because of the length and complexity of the document, neighbors asked for, and got, an extension. Comments are now due before March 19, 2013.]

On most of the forest (44 acres), UCSF plans to cut down trees to achieve a spacing of 30 feet between trees – the width of a small road – and mow down nearly all the understory habitat. On another 2 acres, they will space the trees 60 feet apart.

The stumps of the trees will be covered in black plastic, or else poisoned with Garlon to prevent re-sprouting. Eventually, this will kill the roots, which will start to decay. We’ll address some of these issues in more detail in later posts.

Right now, we want to talk about the number of trees that will be felled. A spacing of 30 feet between trees gives about 50-60 trees per acre. A spacing of 60 feet gives 12-15 trees per acre.

(The easiest way to think about it is that each tree occupies a 30 x 30 foot space, or 900 sq ft. An acre is 43,560 sq ft, so this would give 48.4 trees to an acre. The DEIR calculates it as 61 trees per acre, assuming each tree occupies a circle that’s 30 feet in diameter, 707 sq ft. But there’s no way to arrange circles without wasted spaces between them, so this doesn’t exactly work.)

So on 44 acres, they will retain maybe 50 trees per acre (or maybe fewer). On two more acres with a 60-ft spacing, they will retain 12-15 trees per acre. All the rest will be cut down. Even using the DEIR’s overly optimistic calculation, they will be felling some 31,000 trees. Our calculations are closer to 32,000. Either way, it’s a huge number.

That means that in the 46 acres where UCSF will be felling trees, they will remove more than 90% of the standing trees.

The DEIR says that they will start by cutting down trees that are dead or dying. Aside from their value as habitat (some birds like woodpeckers depend on them), there are not all that many of them in Sutro Forest, which despite everything that has been claimed to the opposite, is a thriving forest. Next in line will be trees with diameters under 12 inches, or roughly 3 feet around – as thick as an adult’s waist. Then they’ll start on the larger trees. Since it’s going to be 90% of the trees, we expect thousands of large trees to be removed.


However, this is not all. We expect further tree losses for four reasons:

  1. Wind throw. Since these trees have grown up in a dense forest where they shelter each other, removing 90% of the trees exposes the remaining 10% to winds to which they’re not adapted. This can be expected to knock down a significant number of the trees not felled. Since the Plan only calls for monitoring the trees and felling any that seem vulnerable to wind-throw, it’s unlikely any vulnerable trees will be saved.
  2. Physical damage. Damage done to the remaining trees in the process of removing the ones they intend to fell. With such large-scale felling, damage to the other trees is inevitable, from machinery, erosion, and falling timbers.
  3. Something like AvatarPesticide damage. This forest has an intertwined, intergrafted root system. When pesticides are used to prevent resprouting on tree-stumps and cut shrubs and ivy, it is quite possible for it to enter the root system and damage remaining trees.
  4. Loss of support. Compounding the effects of the wind-throw, the remaining trees will suffer from a lack of support as the root network dies with 90% of the trees being removed. This could destabilize them, and make them more likely to fail.

What remains will be a seriously weakened forest with a greater risk of failure and tree-loss, not the healthier forest that the DEIR claims. It is likely that the long-term impact of the Project will be the elimination of the forest altogether, and instead will be something like Tank Hill or Twin Peaks plus a few trees.


The project is to be implemented in two phases. In the first phase, trees will be felled and the understory removed in four “demonstration areas” totaling 7.5 acres. They are shown on the map below in yellow, as areas #1-#4. (One of these, #4 “East Bowl”, is the two-acre area slated to have only 12-15 trees per acre.

hand-drawn map not to scale

One area (#5 on the map) is supposed to be a “hands off” area to demonstrate the untouched forest. However, a trail has already been punched through it in November 2011, even before the DEIR had been published.

During this phase, they would experiment with the 3 acres on the South Ridge, just above the Forest Knolls neighborhood. On 1 acre, they would use tarping to prevent regrowth of felled trees; on 1 acre, they would use pesticides, particularly Garlon; and 1 acre they would trim off sprouts by hand. They could also use pesticides on the understory “consistent with city standards” – presumably those of the Natural Areas Program (See article on NAP’s Pesticide Use.)

In the second year, the plan would be extended to the remaining forest, with the proviso that not more than a quarter of the forest would be “thinned” at “any given time

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