Lessons From the Terrible North Bay Wildfires of 2017

This careful analysis of the terrible wildfires in the San Francisco Bay Area is republished with permission from MillionTrees, a website that fights to prevent unnecessary tree removal in the Bay Area.


Lessons learned from fires in the North Bay

Recent wildfires in the North Bay were devastating.  At least 42 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 burning homes ignited the vegetation, 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.

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

SF Fire Department Busts Some Myths

Deputy Fire Chief Mark Gonzales smRecently, Supervisor Norman Yee called a hearing of the Government Audit and Oversight Committee to find out how prepared San Francisco was to deal with fires in brush and forest. The San Francisco Fire Department busted some myths we’ve heard all too often.

MYTH #1:  The forests of San Francisco – in particular those on Mount Sutro and Mount Davidson – are a fire hazard.  Vegetation fires are 12-13 times more likely to occur in grass and brush than in forests. And importantly –  in the north and west of the city, the fog protects it by adding moisture. The south-east is more vulnerable to vegetation fires, particularly around the freeways. (But the real fire danger in San Francisco is from structure fires because of closely-placed wooden houses, not so much from vegetation fires.)

MYTH #2: As city fire-fighters, SFFD wouldn’t know how to respond to a forest fire. Actually, SFFD have 200 fire-fighters trained to fight vegetation fires. This myth is a quarter-century out of date.

MYTH #3: SFFD doesn’t have the equipment or information to fight vegetation fires. Actually,  SFFD has special resources including four maneuverable “mini-pumpers” for fighting outside fires. And it has a mutual aid agreement with other cities and can call on their resources if needed.

MYTH #4: San Francisco’s Wildland Urban Interface is a very high fire hazard severity zone. No, it’s not. It’s not technically a Wildland Urban Interface (though there are some pockets) and the whole of San Francisco has a “moderate” fire hazard severity rating (that’s CALFIRE’s lowest rating).

We attended the hearing, and were impressed by SFFD’s well-planned arrangements. After an introduction from Supervisor Norman Yee who convened the hearing and Fire Chief Joanna Hayes-White who stressed that SFFD was prepared for vegetation fires, Deputy Chief Mark Gonzales gave a detailed presentation on where they happened and how SFFD handled it. This was followed by a talk about  prevention from Lieutenant Mary Shea, (mainly weed-abatement in vacant lots and similar). The Department of Emergency Services’ Bijan Karimi  described preparedness,  to help affected families stay safe and return to normalcy in the event of any disaster. Then Curtis Itson, UCSF’s fire marshal, spoke specifically about Sutro Forest, and finally there were some comments from the public – including a singer!


San Francisco’s main concern is actually more with structure fires, because as Deputy Chief Gonzales said,  “…we have wood buildings in the districts, and they’re all next to each other.”

However, there are some calls for outside fires. They tend to be concentrated around the south and east of the city. Because of the fog, the north and west of the city (i.e., areas that include Mount Sutro Forest and Mount Davidson) are generally moist and not a concern. The focus for outside fires is in the drier South east part of San Francisco: Hunter’s Point, McLaren Park.

grass and outside fire calls - SFFD

From the presentation by Deputy Chief Mark Gonzales:

“… we have fog and even during the drought the rest of the city, the west and the northwest gets the fog. The best weather is in Hunters Point, southeast, so that’s where it’s driest.  One of the concerns is Mclaren park.  So the four mini-pumpers are in that area. We have front line stations in the city.  A lot of those companies have been trained in wild land operations, and the chief mentioned that we have over 200 firefighters that do that.”

The open weedy area around freeways are also a concern. Thrown cigarettes and occasional campfires may account for ignition. He said: “…actually there is a big correlation if you noticed near the freeways… all along and open patches of lands that we respond to, to knock those out.”

When there are vegetation fires, they are mostly in grass and brush. The data the Deputy Fire Chief showed indicated that in the last three years,  fires in grassland and/or brush were 12-13 times more likely than fires in forested areas/ wild lands.

He also pointed out that SFFD did have the resources to fight vegetation fires:

  • Four “mini-pumpers” – small maneuverable trucks for fighting outside fires (as well as operating in crowded conditions). They can go off-road and carry special equipment for fighting vegetation fires.
  • Two hundred firefighters with training in fighting vegetation fires, unlike 20-25 years ago when it had few if any. In fact, 30 of SFFD’s people were deployed to help fight the Butte fire and the Valley fire in other parts of California.
  • There’s a mutual aid arrangement in place that would allow SFFD to call for help if it faced an outside fire it could not control with its own resources. The people it would call on would be at least as well-trained as SFFD’s own fire-fighters – possibly more so because they are from hotter less built-up areas where they experience more outside fires.


Lieutenant Mary Shea, who is responsible for Prevention, started by pointing out that San Francisco was not technically considered a Wildland-Urban interface, though there were pockets that appeared so.  She also said that based on topography and fuel, CALFIRE considered San Francisco a moderate fire hazard area, not a high fire hazard zone. [“Moderate” is actually CALFIRE’s lowest rating.]

 not WUI fire area
Her prevention efforts therefore  focused on overgrowth of weeds, grass and vines,  30-foot defensible spaces, tree-limbs within 10 feet of chimney outlet, buildup of leaves or pine needles on roofs.

SFFD weed abatement program

They mainly responded to complaints from neighbors, perhaps half of which were justified and the remainder were people disgruntled with the next-door tree overhanging their house or yard. They usually sent out abatement notices two weeks before 4th of July. Owners usually complied and most yards were well-maintained – the owners didn’t want fires, either. The main problem was in abandoned properties where the neighbor could not be found, or people unable for some reason to maintain their homes. SFFD worked with such cases to ensure safety. Most notices came from Hunters Point/ Bayview around the freeways, and Bernal, places like that.

Chief Joanna Hayes-White praised UCSF for the “fire safety” work 2 years ago, and they said they would be reviewing it this fall. She talked about defensible space and fuel reduction.

UCSF’s  fire marshall, Curtis Itson, emphasized that UCSF has a commitment to keep buildings, visitors, and nearby neighborhoods safe.

In comments, we pointed out that given the fog and the way the vegetation trapped moisture, we needed to be careful that we did not increase fire hazard by reducing the forest’s ability to retain moisture.

More important public comments:

  • In the parks and Golden Gate National Recreation Area, native plant interests are felling trees and substituting more-flammable native plants for fire-resistant non-natives like trees and ice-plant. These landscape transformations increase fire hazard.
  • Trees are a lot less flammable than the myths say. In the parks,  trees are felled and left on the ground as fuel, while toxic herbicides are in use. SFRPD’s forest management needs improvement.
  • Someone  talked about dying trees as fire hazards along O’Shaughnessy, and a singer sang that it would be alright.

If you want to view the hour-long hearing, here’s the LINK.

Mt Davidson’s Moist Green Forest in September 2015

Moisture content of vegetation is one of the key determinants of fire hazard. In Mount Davidson, the drier side is clearly the native plant area, not the forest. This visitor went up to the forest to see – and document –  how the drought has affected the plants under the trees. Here, after four years of drought, is Mt Davidson’s forest.
This is another of our Park Visitor series: First-person accounts of visits to our San Francisco parks.


Mt Davidson google map

This google earth view shows the forest on the west side of the park and the grassland on the east side. Homes surrounding the park are also visible. I walked from the north side from Rockdale Drive and ended on the south side along Myra Way.

A presentation by Michie Wong, SFFD fire marshal, to the SF Urban Forestry Council, stated that the condition of the forest floor is the key to fire hazard. If it is green it is not flammable, but dry grass and shrubs are.

How has several years of drought affected the understory in the forest at Mt. Davidson Park? I visited the forest to see and document the moisture conditions in the forest’s understory. This article comprises my pictures and notes.


Mt Davidson 1 - entrance with NAP warning sign and blackberry bushesNatural Areas Sign at trail entrance surround by green berry bushes.

Mt Davidson 2 - fuschia flourishing despite drought, watered by the trees catching the fogFurther up the trail on the north side of the park fuchsias thrive despite years of drought.

Mt Davidson 3 - greenery along pathwayHere’s a close-up of greenery on the forest floor.

Mt Davidson 5 - the girdled tree still has moisture and is sproutingWalking east to the grassland part of the park.  A eucalyptus tree has new sprouts — despite the drought and despite being girdled in attempt to kill it.

The greenery around it has been cleared or killed with herbicides for planting of natives species, now marked with green flags.

Mt Davidson 6 - the native plants are dry and flammableView of dead grass and shrubs among native coyote bush on east side of park.

Mt Davidson 7 - dead and dry plants near homesDead and dry vegetation next to houses.

Mt Davidson 8 - standing water while the native plants are dryHeading west in the park into the forest along the fire road.

A 4-foot wide puddle remains from the recent drizzle and thick fog that followed a week of record heat. It is typically muddier on Mt. Davidson in the summer (the “fire season” elsewhere) than the winter because of the fog.

Mt Davidson 9Heading down the fire road to the west side of the park.

Mt Davidson 10 Ferns on roadside despite the droughtFerns growing in the rocky slopes despite the drought.

Mt Davidson 11 - roadside grass and plants are greenGrass along the road is green and the ivy too.

Mt Davidson 12 - lush greenery on both sides of trailLush greenery on the both side of the road on the western side of the park.

Mt Davidson 13 - only watered by the trees catching fog its still green during droughtFurther down the hill, at the intersection with the Juanita trail.  No sign of drought here, despite no one ever watering this area like they do in Golden Gate Park.

Mt Davidson 14 - Southern side with sun exposure - still greenSouthern entrance to the park, with most sun exposure, is still green too.

Mt Davidson 15 - ivy is green and not flammableBoundary of park next to homes on Myra Way.

Ivy on forest floor has been cleared from fence but remains green and not a fire hazard.

We thank this Park Visitor for this report. We would especially like to draw attention to the picture of the girdled eucalyptus. Despite the effort to kill this tree, it still contains a lot of moisture – as evident from the sprouts. The grass and shrubs on the East side of the mountain are far more flammable.

FEMA Rule Change Could Make Tree-felling Easier

Very often, land managers seeking funding for a project look to the Federal Emergency Management Agency (FEMA) for funds. FEMA provides money for fire hazard reduction, and if the project can be presented in those terms, the land managers can apply for a grant.

Until now, if a project seeking FEMA funding was large enough, FEMA asked the project sponsors for an Environmental Impact Report. This made a lot of sense: Fire hazard reduction projects have massive impacts on the landscape and habitat, much of it negative.


Now,  FEMA plans a “programmatic environmental assessment (PEA) to evaluate the potential beneficial and adverse impacts from eligible wildfire mitigation activities funded under the Hazard Mitigation Grant Program (HMGP) and Pre-Disaster Mitigation (PDM) Program.” What this amounts to is that fire hazard reduction projects would be “pre-cleared” from an environmental standpoint. FEMA is planning to make this a nationwide measure.

It would apply to  three types of wildfire mitigation projects to protect buildings and structures on the Wildland-Urban Interface (i.e. where structures are within 2 miles of a wildland):

  • “Defensible space—The creation of perimeters around residential and non-residential buildings and structures through the removal or reduction of flammable vegetation;
  • “Structural Protection through Ignition-Resistant Construction—The application of non-combustible building envelope assemblies, the use of ignition-resistant materials, and the use of proper retrofit techniques in new and existing structures; and
  • “Hazardous Fuels Reduction—Vegetation management to decrease the amount of hazardous fuels; vegetation thinning; and reduction of flammable materials to protect life and property beyond defensible space perimeters but proximate to at-risk structures.”

The first two measures are not controversial, and can reduce hazard with a relatively minor environmental impact. However, the third one – Hazardous Fuels Reduction – is much more problematic for the environment.


Tree removal – for whatever reason – is one of the costliest activities for a land manager. This makes any potential source of outside funding attractive.  FEMA is one such source. So if any tree-felling project can be presented as hazard reduction, it has a chance of obtaining such funds. Not having to do an environmental impact report would make the money more easily accessible.

However, removing  trees also has a significant environmental impact, which can be greater or lesser depending on the size of the project, the topography of the site, and the ecological system that would be affected. Some of the impacts:

  • Hydrology: Removing trees affects water flow and can lead to problems with erosion
  • Slope stabilization issues: The root systems of trees – especially older, mature trees that may have intergrafted roots – stabilize slopes. Removing trees can contribute to slope failures years – even decades – later.
  • Carbon sequestration: Trees capture and store carbon, fighting global warming. Felling trees stops them from collecting the carbon, and  returns it to the atmosphere.
  • Toxic herbicides: In many of these projects, managers plan to use large amounts of herbicides to prevent tree regrowth. This can end up in the soil and water, and also affect people, pets and wildlife using the lands.
  • Pollution: Trees and vegetation help fight pollution, particularly particulate pollution, by trapping particles on their leaves until they’re washed to the ground by rain.

And of course, removing trees affects the beauty and recreational value of these areas. It’s only by evaluating the environmental impact of individual projects that FEMA can determine if the negative environmental impact would be worth the hazard reduction – if any. Ironically, many of these projects would actually increase fire hazard, because removing the trees encourages growth of scrub and grass that ignite more easily and support fast-moving fires.

We’ve been concerned because we think that Native Plant “restoration” projects are often presented as hazard reduction projects. In 2008, FEMA received such an application for tree-felling in Sutro Forest. More recently, FEMA was asked to fund the removal of hundreds of thousands of trees in the East Bay.


FEMA is accepting comments until August 18th, 2014 – this coming Monday. The comments have to be submitted at their website (not by email). Here’s how:

  1. Go to the Federal eRulemaking Portal: http://www.regulations.gov
  2.  In the Search space that comes up, input FEMA-2014-0021
  3.  Then click on Open Docket folder at the right.
 (Or try this link: HERE )

They’re not interested in comments that look like a mass mail campaign, so to have an impact, you would have to write a the comment individually.

Great horned owlets in eucalyptus. San Francisco. Janet Kessler

Open Letter to Jake Sigg: Transparency

[Note: This article is slightly modified from one that originally appeared at SutroForest.com.]

This is an open letter to Jake Sigg who has wrongly criticized the San Francisco Forest Alliance and Save Sutro Forest. We invite Mr. Sigg – doyen of San Francisco’s native plant activists and publisher of an email newsletter – to talk directly with us any time. We believe that talking to people with a different point of view is important.

However, let’s set the record straight with facts, shall we?


Dear Mr. Sigg,

Yesterday, your newsletter published a post regarding CalFire’s assessment of risk in San Francisco. It  included an astonishing allegation:

SF Forest Alliance/sutroforest.com has been known for selective quotations that alter or reverse what writers intended. We have all learned to question authority and to insist on transparency. SFFA/sutroforest.com needs to become transparent in its messages. Its withholding of the complete opinion of Cal-Fire deprives the public of the information it needs to protect itself.”


We object. We never “alter or reverse” what writers intended. We stand for transparency, and try as far as we can to include references so people can go back and look at sources if they wish. (In this post, relevant links are at the end of this article.)

Nor have we (or SutroForest.com) withheld “the complete opinion of CalFire.” In fact, what we have quoted of CalFire is taken from two sources that you or other readers may verify: The CalFire website; and the FEMA letter about Mount Sutro Forest.

(1) The CalFire website.

That is where we obtained this map, which shows that CalFire gives its lowest hazard rating to Sutro Forest (and most of San Francisco). We provide that link again here: CalFire Hazard Map.

CAL FIRE map shows Mt Sutro Forest has the lowest level of fire hazard (gray color indicates areas not rated - mainly built areas)

CAL FIRE map shows Mt Sutro Forest has the lowest level of fire hazard (gray color indicates areas not rated – mainly built areas). The blue and pink pointer lines added by us.

We also referred to the page on the CalFire website, where in an update it said:  “Update, 11/2008:
CAL FIRE has determined that this county has no Very High Fire Hazard Severity Zones (VHFHSZ) in LRA [Local Responsibility Area]…”

(2) A letter from FEMA to Cal EMA regarding UCSF’s application for funding to cut down trees on Mount Sutro.

Here is an excerpt from that letter, originally posted at SutroForest.com. It includes a conversation that FEMA had with a Wildland Fire Scientist in CalFire:

fire hazard FEMA critWe do not think that “alters or reverses” the intent of the letter. But if you wish to verify this, the full letter is linked at the end of this article.


Now for the substantive objection. We think that what we’re seeing is different conclusions reached by our opponents and ourselves.

What CalFire explained is that fire has two factors: Fuel Rank, and Rotation Rank (or the risk of ignition). Fuel rank is only density of vegetation, and all agree that the vegetation density in Mount Sutro Forest is high.

The second factor is the risk of ignition, and that is low in most of San Francisco. (The CalFire map above shows a little orange spot on the edge of San Mateo County that has High – but not Very High – risk.) San Francisco’s climate is cool and not extreme. Right now, while the rest of the country has a heat wave, the fog blows through our city.

forest 6Ignition risk is particularly low in Mount Sutro Forest, which lies directly in the city’s fog belt (as also in Mount Davidson, for the same reason). The Cloud Forest effect increases moisture levels considerably as the trees harvest moisture from the fog, and store it in the dense understory. It’s obvious that the best way to keep ignition risk low is to trap that moisture and reduce evaporation.

The post included in your newsletter describes an anonymous conversation with an unnamed person within CalFire.   It is unclear what recommendations discussed there come from the interviewer, or from an individual within CalFire. (Though you apparently consider it the “complete opinion of Cal-Fire,” it does not appear on the CalFire website.)

We hope to make our own contact with CalFire, and report on it.


Even if the UCSF Plan for Sutro Forest reduced the Fuel Rank (and we don’t see how it would, given that the Plan would be to fell the trees and leave them there as logs and chips), it would raise the ignition risk by drying out the forest, reducing both harvested and retained moisture, and by increasing wind velocities in this very windy part of San Francisco.

FEMA had similar questions for UCSF. This is again a quote from the same letter cited above.

FEMA Letter - drying the forestThis doesn’t look like a good trade-off, especially since this is not a distant wild-land, but in the midst of the city with access to water sources and fire-fighting capability.

map usgs ed paved roads in Sutro ForestThere is actually a fire-station on the Stanyan side of the forest, a fact that was cited during the hearing about opening the trail from Stanyan into the forest through SF RPD’s Interior Greenbelt. At that meeting, Ray Moritz (who was also hired by UCSF separately) allayed neighbors’ concerns about increased ignition risk from such a trail by saying that overall risk was low. The report of that meeting, written from contemporaneous notes, is HERE.

We don’t think a model based on increasing ignition risk while reducing fuel is workable for this site. And aside from the environmental damage this “solution” would cause, in reduced carbon sequestration, poorer pollution control, potential hillside destabilization, increased water run-off, lost habitat, and use of substantial amounts of toxic pesticides – this is not reversible in the short or medium term. If we discover it’s all a horrible mistake, it cannot be undone once the trees lie on the ground as logs and chips.


1.  CalFire references:

  • Map is linked HERE
  • Update noting no “Very Severe Fire Hazard” HERE

2.  FEMA Letter (in two parts):

Mt Sutro PDM – Letter from FEMA – Environmental-Pt 1

Mt Sutro PDM – Letter from FEMA – Environmental-Pt 2

And if anyone wishes to further verify that this indeed is the letter – it is available to anyone who requests it under the Freedom of Information Act from FEMA, and as Public Records Information from UCSF.

Fire at McLaren Park: Letter from a Park-Lover

We received this letter from a frequent visitor to McLaren Park. It’s published here with permission and minor edits.

Only a small part of the grassland that burned south of Mansell Drive

Dandelion and thistle seeds survived the fire – a feast for the birds

I was at McLaren a few days ago and the seasonally dry, “Natural Areas” grassland south of Mansell is burnt. I can’t find anything on the web about the fire but it looks like it started about 50 feet from a homeless encampment at the bottom of the hill close to lower Visitacion.  (It also could have been started by fireworks.)

Unlike the Stern Grove fire last week, which burned a small area in the ivy-covered forest, the McLaren grass fire burned a pretty large area – I’d guess 5 to 8 acres. Interestingly, a few coyote bushes burned but most didn’t. The non-native dandelions and bull thistle seeds did not burn, and were blowing across the burnt area. Loads of birds were eating the white fuzzy seeds. It will be interesting to see what the grassland looks like as it grows back.

Leaf litter didn’t burn

Burning certainly is a concern in the city but fire was a key part of the Native American ecosystem when Europeans arrived.

Fire, missing grazing, large predators, climate changes, and air pollution, are all reasons it is futile to pretend San Francisco Native Heritage can be restored.


In the forest south of Mansell,  I saw several young pines, which contradicts a Rec & Park forestry report that says pines and cypress are not naturally regenerating in San Francisco parks.  (I’ve also seen young cypresses deep in the forest at Mt Davidson.  Sadly, even when I showed a seasoned Native Plant Advocate the young cypresses and eucalyptus, he still insisted that trees can’t regenerate in the forests and the forests are unsustainable.)

Recently cut young trees

San Francisco is paying millions for “reforestation” projects at the same time they are cutting down healthy pine trees and self-sustaining forests?

Of course, even Rec & Park can’t deny that eucalyptus is self-sustaining because of the young sprouts throughout the park forests that they haven’t managed to cut down.  It is so sad to see the many poles of young pines and eucalyptus cut and lying on the ground in piles of dry leaves throughout the McLaren forests. Are the Natural Areas “volunteers” or staff surreptitiously implementing the Natural Areas tree-thinning program even before the environmental impact report is completed?

Strange that the city spends millions for a plan and draft environmental impact report but appear to be moving forward with their plans as if it is just an expensive formality.  What is sad is the proposed plan isn’t even the “environmentally superior plan” per the city’s own analysis.  It is bizarre that native plant advocates have hijacked the term “environmentalist” to mean native plants.  Other cities recognize the health and environmental benefits of a healthy forest, while “environmentally conscious” San Francisco is deliberately chopping healthy trees down as if they are garbage.


The road/trail at the bottom of the hill also has fennel sprayed with pesticides along the trail right above the homeless encampment, which is visible from that trail. I wish Rec & Park would clean up the garbage that they walk by instead of spending their time spraying pretty, green fennel.

Garbage left from a homeless encampment near the trail/road.

I really think it is disturbing that the Natural Areas are the only parks exempt from any maintenance standard, even the one that says no more than 15 pieces of litter visible in a 50′ by 50′ area.   This means Rec & Park has exempted one-fourth of the land managed by Rec & Park from the voter-passed Prop C requirements for park maintenance standards and monitoring.

A few months ago, I broke my habit of walking the trails between the reservoir and the tennis courts for the less-travelled trails of McLaren.  I particularly love the rolling hills with flocks of birds, trees, wildflowers, and meadows and that our walks are so much longer.  However, I’m not as thrilled about spending much of my walk trying to make a dent in the accumulated litter.

I’m surprised anyone was taking the trails, considering the uninviting litter accumulated at the Visitacion Avenue/Mansell Street entrance.  I cleaned about half, but the other half still looks like a dumping zone in an abandoned park.  It makes me appreciate the daily dog-walkers and others that clean up in the more-travelled park areas.  At least Rec & Park should routinely pick up at the entrances and parking areas and keep them relatively clean.

DESTRUCTION OF PLANT-LIFE: The “Natural” Areas Program

Personally I prefer the green left side to the “restored” right side with bare ground

On the other side of McLaren in the forest area, I found a volunteer working alone, pulling up the English ivy from the forest floor to leave bare ground. He has, he said, a “permit” from Rec & Park and has been trained to pull the ivy and that it is overrunning the park.  I’d personally rather see green ivy than bare ground covered in pine needles.  Especially since ivy, which flowers and bears berries early in the season, provides some wildlife food and shelter, absorbs carbon dioxide and air pollution, and makes the park feels more alive.

It is quite bizarre that Rec & Park and native plant advocates claim nothing grows under the non-native trees.  In reality that is true only because Natural Areas contingent is out there constantly pulling up the dense and diverse vegetation, which is prolific in eucalyptus, pine and cypress forests that are left natural or are lucky enough to be protected in Golden Gate Park.  (I still find it bizarre the maligned “invasive” plants and trees protected in one of San Francisco’s most precious gems, Golden Gate Park, are being sprayed, pulled and cut in neighborhood parks.)


When I mentioned that the Natural Areas plan has not been approved, he said it was okay to proceed because the plan was developed long ago. He implied dog people are the problem and that it wasn’t right that the dog people think the area is just for them. I said that people with dogs are about 40% of the population. Did having a dog mean that one shouldn’t have a voice in how the parks are used?

I wonder how many people are native plant gardening purists who want trees removed simply because they aren’t San Francisco Native Heritage?  Dog play areas are only about 100 acres, yet  native plant advocates call people with dogs greedy while The Natural Areas Program claims over 1000 acres. It’s concerning to take a dog or a child to an area that has been sprayed with herbicides.

Sadly, I saw at least 4 places with glass in the parking lots from broken car windows. (It’s the first time I’ve personally seen that at McLaren.) The broken glass and homeless encampment suggest that what McLaren Park really needs to make it safer is more visitors, not fewer trees, dogs or activities.

Natural Areas Plan: SFFA comments on the DEIR (Pt 7: False “Fire Hazard” Assumptions)

One of the most problematic assumptions in the Significant Natural Resource Area Managment Plan (SNRAMP – Sin-ramp) is that the eucalyptus forests are a fire hazard, and that thinning/ felling them, removing the existing understory, and substituting native plants will reduce the danger.

It won’t.

First, in San Francisco’s foggy climate, the eucalyptus trees actually harvest moisture, and the dense naturalized understory traps this moisture. These are some of the wettest areas in the city through the peak fire season. Second, eucalyptus is actually less flammable than most native plants.  Finally, the tall trees act as an effective wind-break, thus reducing the risk of wind-driven fires.

Read on for details.

The Draft Environmental Impact Report (DEIR) for the Significant Natural Resource Areas Management Plan (SNRAMP) makes assumptions regarding fire hazards in San Francisco for which it provides no scientific or experiential evidence:

  1. That native vegetation is less flammable than non-native vegetation
  2. That thinning trees will reduce fire hazard

These assumptions are false and we will provide scientific and experiential evidence that they are false.  Unless the final EIR can provide scientific evidence and/or actual experience to support these assumptions in the DEIR, these statements regarding fire hazards must be revised to be consistent with available evidence.


The DEIR makes the following claims:

  • “…maximize indigenous vegetation for fire control.”  (DEIR, page 78)
  • “…vegetation with high fire hazard ratings such as broom and eucalyptus.” (DEIR, page 111,396)
  • “…replacing highly flammable eucalyptus trees with more fire resistant species.”  (DEIR, page 410)

Fear of fire has fueled the heated debate about native plant restorations in the Bay Area.  Native plant advocates want the public to believe that the non-native forest is highly flammable, that its destruction and replacement with native landscapes would make us safer.  Nothing could be further from the truth.  The fact is that the forest—whether it is native or non-native—is generally less flammable than the landscape that is native to California.  In the specific case of the Sutro Forest in San Francisco, this general principal is particularly true:  the existing forest is significantly less flammable than the landscape that is native to that location.

The “Mount Sutro Management Plan” was written by UCSF and is available on their website.  It describes “native” Mount Sutro as follows:  “In the 1800s, like most of San Francisco’s hills, Mount Parnassus [now known as Mount Sutro] was covered predominantly with coastal scrub chapparal [sic], consisting of native grasses, wildflowers, and shrubs…”  (page 4)  (emphasis added)

A Natural History of California  [Ref: Allan Schoenherr, UC Press, 1992, page 341] tells us that chaparral is not only highly flammable, but is in fact dependent upon fire to sustain itself:

“Chaparral…is…most likely to burn.  The community has evolved over millions of years in association with fires, and in fact requires fire for proper health and vigor.  Thus it is not surprising that most chaparral plants exhibit adaptations enabling them to recover after a burn…Not only do chaparral plants feature adaptations that help them recover after a fire, but some characteristics of these plants, such as fibrous or ribbonlike shreds on the bark, seem to encourage fire.  Other species contain volatile oils.  In the absence of fire, a mature chaparral stand may become senile, in which case growth and reproduction are reduced. “  (emphasis added)

The local chapter (Yerba Buena) of the California Native Plant Society acknowledges the value of fire to restore and maintain native plant populations.   A wildfire fire on San Bruno Mountain in native grassland and coastal scrub “consumed about 300 acres” in June 2008, according to an article on their website.    The article reports that

“Fire is an adaptive management tool that, along with natural grazing and browsing, has been missing in promoting healthy grasslands that once covered much of the lower elevations of California…The threats to native grasslands are invasions of non-native grasses and forbs, and succession by native and invasive shrubs.  Fortunately the fire scrubbed the canyons pretty clean of just about everything.  This gives the land a shot of nutrients to recharge the soil and awaken the seedbanks that have long been lying dormant.”

The fire on Angel Island in October 2008, demonstrates that native grassland is more flammable than the non-native forest.  According to an “environmental scientist” from the California state park system, 80 acres of eucalyptus were removed from Angel Island 12 years ago in order to restore native grassland.  Only 6 acres of eucalyptus remain.  [Ref:“Rains expected to help heal Angel Island,” SF Chronicle, October 14, 2008]   The fire that burned 400 acres of the 740 acres of Angel Island in 2008 stopped at the forest edge:  “At the edge of the burn belt lie strips of intact tree groves…a torched swath intercut with untouched forest.”  [Ref:  “After fire, Angel Island is a park of contrasts,” SF Chronicle, October 15, 2008]  It was the native grassland and brush that burned on Angel Island and the park rangers were ecstatic about the beneficial effects of the fire:  “The shrubs—coyote bush, monkey flower and California sage—should green up with the first storms…The grasses will grow up quickly and will look like a golf course.”  Ironically, the “environmental scientist” continues to claim that the eucalyptus forest was highly flammable, though it played no part in this fire and there was no history of there ever having been a fire in the eucalyptus during the 100 years prior to their removal.

Unfortunately, the 1991 fire in the Oakland hills has enabled native plant advocates to maintain the fiction that eucalyptus is highly flammable.  And in that case there is no doubt that they were involved in that devastating fire.  However, there were factors in that fire that are not applicable to San Francisco.  The climate in San Francisco is milder than the climate in the East Bay because of the moderating influence of the ocean.  It is cooler in the summer and warmer in the winter.  There are never prolonged, hard freezes in San Francisco that cause the eucalyptus to die back, creating dead, flammable leaf litter.  The 1991 fire in the Oakland hills occurred in the fall, following a hard winter freeze that produced large amounts of flammable leaf litter.  In fact, there were several wildfires in the Oakland hills in the 20th century.  Each followed a hard winter causing vegetation to die back.

According to the FEMA Technical Report, the 1991 Oakland hills fire started in grass, spread to dry brush, and was then driven by the wind to burn everything in its path.  The fire burned native plants and trees as readily as eucalyptus.

When it is hot and dry in the Oakland hills, as it was at the time of the 1991 fire, it is cool and damp in San Francisco.   Fogs from the ocean drift over the eucalyptus forests, condensing on the leaves of the trees, falling to the ground, moistening the leaf litter.  [Ref: Gilliam, Harold, The Weather of the San Francisco Bay Area, UC Press, 2002]  When the heat from the land meets the cool ocean air, the result is the fog that blankets San Francisco during the summer.  These are not the conditions for fire ignition that exist in the Oakland hills.

UCSF applied for a FEMA grant to fund its project to destroy the eucalyptus forest and restore native chaparral, based on its claim that the eucalyptus forest is highly flammable.  In its letter of October 1, 2009 (obtained by FOIA request), FEMA raised questions about UCSF’s claim of fire hazard.  (See Attachment VII-A.)  FEMA asked UCSF to explain how fire hazard would be reduced by eliminating most of the existing forest, given that reducing moisture on the forest floor by eliminating the tall trees that condense the fog from the air could increase the potential for ignition.  FEMA also asked UCSF to provide “scientific evidence” to support its response to this question.  Rather than answer this and other questions, UCSF chose to withdraw its FEMA application.

The reputation of eucalyptus as a fire hazard is also based on the assumption that oils in its leaves are flammable.  The National Park Service reports on its website that the leaves are, in fact, fire resistant:   “The live foliage [of the eucalyptus] proved fire resistant, so a potentially catastrophic crown fire was avoided.”

The predominant species of eucalyptus in California, the blue gum eucalyptus (E. globulus) is native to Tasmania.  Scientists at the University of Tasmania conducted laboratory experiments on the plants and trees in the Tasmanian forest to determine the relative flammability of their native species.  The blue gum eucalyptus (E. globulus) is included in this study.  The study reports that, “E. globulus leaves, both juvenile and adult, presented the greatest resistance [to ignition] of all the eucalypts studied.  In this case, leaf thickness was important as well as the presence of a waxy cuticle.”  Also, in a table entitled “Rate of flame front movement,” the comment for E. globulus leaves is “resistant to combustion.”  [Ref:  Dickinson, K.J.M. and Kirkpatrick, J.B., “The flammability and energy content of some important plant species and fuel components in the forests of southeastern Tasmania,” Journal of Biogeography, 1985, 12:  121-134.]  In other words, despite the oil content in the leaf, its physical properties protect the leaf from ignition.

Even if oils were a factor in flammability, there are many native plants that are equally oily, such as the ubiquitous coyote brush and bays.  According to Cornell University studies, essential/volatile oils in blue gum eucalyptus leaves range from less than 1.5 to over 3.5%.   The leaves of native California bay laurel trees contain 7.5% of essential/volatile oils, more than twice the amount of oil in leaves of blue gums.

These principles are best illustrated by a photograph of an actual fire in San Diego in 2003 in which all the homes burned to the ground, but the eucalyptus forest surrounding those homes did not ignite:

Source: New York Times

Likewise, non-native broom is not more flammable than its native counterpart in the chaparral plant community, coyote brush.  The leaves of both shrubs are small, the fine fuel that ignites more readily than larger leaves and branches.  But the leaves of native coyote brush contain oil not found in non-native broom.  And the branches of broom are green to the ground, unlike the branches of coyote brush which become woody thickets with age.  Broom therefore contains more moisture than coyote brush, which reduces its combustibility.

Fire is an essential feature of the landscape that is native to California.  [Ref: Sugihara, Neil, Fire in California’s Ecosystems, UC Press, 2006]  Destroying a non-native forest in order to create a native landscape of grassland and scrub will not reduce fire hazard.


The DEIR makes the following claim:

“…timber thinning would increase the space between trees, reducing the ability of a fire to rapidly spread.” (DEIR, page 396)

Most fires in California are hot, wind-driven fires in which everything burns.  The composition of the fuel load in a wind-driven fire is irrelevant.  Everything in its path will burn. [Ref:  Keeley, J, and Fotheringham, “Impact of past, present, and future fire regimes on North American Mediterranean shrublands, pages 218-262 in Veblen, et al., editors, Fire and climate change in temperate ecosystems of the Western Americas, 2003.]  The 1991 fire in the Oakland hills was an example of such a fire.  According to the FEMA technical report on that fire, both native and non-native vegetation, as well as about 3,800 homes burned in that fire.

Windbreaks are therefore one of the few defenses in a wind-driven fire.  For that reason, in its letter of October 1, 2009 (see attachment VII-A), FEMA asked UCSF to explain how the destruction of the tall trees on Mount Sutro would reduce fire hazard.  FEMA noted that eliminating the windbreak that the tall trees provide has the potential to enable a wind-driven fire to sweep through the forest unobstructed.  FEMA also asked UCSF to provide “scientific evidence” to support its answer to this question.  We repeat, UCSF chose to withdraw its application for FEMA funding of its project rather than answer this question.

In 1987, 20,000 hectares burned in a wildfire in the Shasta-Trinity National Forest.  The effects of that fire on the forest were studied by Weatherspoon and Skinner of the USDA Forest Service.  They reported the results of their study in Forest Science. [Ref: Weatherspoon, C.P. and Skinner, C.N., “An Assessment of Factors Associated with Damage to Tree Crowns from the 1987 Wildfires in Northern California,” Forest Science, Vol. 41, No 3, pages 430-453]  They found the least amount of fire damage in those sections of the forest that had not been thinned or clear-cut.  In other words, the more trees there were, the less damage was done by the fire.  They explained that finding:

“The occurrence of lower Fire Damage Classes in uncut stands [of trees] probably is attributable largely to the absence of activity fuels [e.g., grasses] and to the relatively closed canopy, which reduces insolation [exposure to the sun], wind movement near the surface, and associated drying of fuels.  Conversely, opening the stand by partial cutting adds fuels and creates a microclimate conducive to increased fire intensities.” (emphasis added)

In other words the denser the forest,

  • The less wind on the forest floor, thereby slowing the spread of fire
  • The more shade on the forest floor.
    • The less flammable vegetation on the forest floor
    • The more moist the forest floor

All of these factors combine to reduce fire hazard in dense forest. Likewise, in a study of fire behavior in eucalyptus forest in Australia, based on a series of experimental controlled burns, wind speed and fire spread were significantly reduced on the forest floor. [Ref: Gould, J.S., et. al., Project Vesta:  Fire in Dry Eucalyptus Forests, Commonwealth Scientific and Industrial Research Organization and Department of Environment and Conservation, Western Australia, November 2007]

Furthermore, a recently published study corroborates that thinning the forest does not significantly reduce fire risk, nor does it increase carbon storage in the forest. [Ref: John L. Campbell, Mark E. Harmon, Stephen R. Mitchell, “Can fuel-reduction treatments really increase forest carbon storage in the western US by reducing future fire emissions? Frontiers in Ecology and Environment, 2011, 10,1890/110057.]

“It has been suggested that thinning trees and other fuel-reduction practices aimed at reducing the probability of high-severity forest fire are consistent with efforts to keep carbon (C) sequestered in terrestrial pools, and that such practices should therefore be rewarded rather than penalized in C-accounting schemes. By evaluating how fuel treatments, wildfire, and their interactions affect forest C stocks across a wide range of spatial and temporal scales, we conclude that this is extremely unlikely. Our review reveals high C losses associated with fuel treatment, only modest differences in the combustive losses associated with high-severity fire and the low-severity fire that fuel treatment is meant to encourage, and a low likelihood that treated forests will be exposed to fire.  Although fuel-reduction treatments may be necessary to restore historical functionality to fire-suppressed ecosystems, we found little credible evidence that such efforts have the added benefit of increasing terrestrial C stocks.”  (emphasis added)

Thinning the forest will not reduce fire hazard.  In fact, it will increase fire hazard.

The DEIR also says that fire hazard will be reduced by removing dead trees:

Removed trees would include those that are diseased and dying, thereby reducing easily combustible fuel loads.” (DEIR, page 396)

We do not dispute that dead trees are more flammable than living trees because they contain less moisture, one of the key variables in combustibility.  However, we have established in another comment (Part I) that the claim that only dead and dying trees will be removed is contradicted by the SNRAMP which the DEIR is supposedly evaluating.  There is no evidence that the trees that will be removed are dead or dying.  Furthermore, if the predictions of experts on Sudden Oak Death prove to be true, 90% of the native oak woodland which SNRAMP proposes to expand will be dead and highly flammable within 25 years. [Ref: Fimrite, Peter, “Sudden oak death cases jump, spread in the Bay Areas,” San Francisco Chronicle, October 2, 2011]


Unless scientific evidence can be provided to support statements in the DEIR regarding fire hazard, the final EIR must be corrected to reflect the scientific and experiential evidence that refutes it:

  • Native vegetation is not inherently less flammable than non-native vegetation, including eucalyptus
  • Thinning the forest will not reduce fire hazards.