San Francisco, Biodiversity, and the Department of the Environment

We’re aware of San Francisco’s Department of the Environment as the first line of defense against toxic chemicals in our public lands. But they’re more than the defense-against-the-dark-chems guys. They’re the recycling guys. The energy saving guys. The community gardens and Green Businesses guys. Now they’re adding Biodiversity to their long-term plans. Here are some notes from the minutes of the San Francisco Commission for the Environment’s May 2011 meeting:

The addition of a section on Biodiversity for 2013 plans and beyond and possibly before then if funding is secured.  This calls for a focus on protecting the natural environment beyond trees, which is the focus of the urban forestry program.

The minutes indicated support from Commissioner Ruth Gravanis (the Commission’s Vice President):

Commissioner Gravanis stated that she is pleased that a biological diversity section has been added, one area in which San Francisco cannot claim to be an international leader, and is looking forward to working closely with staff to make that happen.   She suggested that the Climate Adaptation Plan address that our own indigenous biological resources are imperiled by climate change and the invasion of exotic species in particular.

And another from the Sierra Club.

Ms. Rebecca Evans, Sierra Club, spoke in support of Director Nutter’s addition of biodiversity to the Strategic Plan, which was further expanded on by Commissioner Gravanis.  She stated that she attended a meeting of the San Francisco League of Conservation Voters where a discussion was held on San Francisco making biodiversity a priority.  It is time for the city to look at this issue and embrace it.  The Golden Gate National Recreation Area has more than 1200 endangered species, more than any other park in the lower forty-eight and we are on the Pacific flyway.

Biodiversity. It’s a good thing. So why aren’t we standing and cheering?


Biodiversity means different things to different people, and we’re concerned about the interpretation here. From Commissioner Gravanis’ remarks, it’s clear the focus is on native plants and excludes “exotic” species.

We have several problems with this.

  • First, it can destroy existing habitats and ecosystems in pursuit of an idealized, modified one. This ignores the animal life that depends on the existing ecosystems; and it ignores established ecosystems that probably function better than a newly-established one. (This is what we see in Mount Sutro Forest: A lack of recognition of the unique century-old fog-forest ecosystem, only because it comprises non-native plants.)
  • For instance: In “natural” areas, “non-native invasive” blackberry thickets are being torn out and sprayed with pesticides such as Roundup and Garlon. This destroys habitat; these thickets provide valuable hiding places and food sources for birds and animals. It also destroys a source of berries, ignoring the pleasure people get from foraging. Sometimes, people pick them anyway, unaware that they may have been sprayed with chemicals not necessarily suitable for food crops.
  • Second, it will inevitably require the use of toxic pesticides. In the city’s “Natural” areas, Roundup and Garlon have been widely used; lately, Imazapyr has been added to the arsenal. Roundup, one of the world’s most widely-used pesticides, has been implicated in birth defects in animals and possibly people. In San Francisco, it’s a Tier II pesticide, where Tier I is the most toxic. The SF DOE classifies Garlon, which is much more toxic, as Tier I. Imazapyr, which has recently been introduced for use in “natural” areas, is also Tier II, but has its own problems. It’s banned in Europe.
  • Third, we are concerned about open spaces as recreation.  Who uses these areas the most? We’ve been out there on weekdays, and on weekends. The number one users are dog-walkers, whether walking their own dogs or other people’s. These are the people who *need* to be out of their homes twice a day, with their dogs.  Joggers are the second, together with others who use the parks for exercise: such as (where permitted) bike-riders. Third most common: children with accompanying adults. A distant fourth would be those who are watching birds or merely observing nature — except, of course, that other users also do this. (This breakout doesn’t apply to Twin Peaks, which is a view-platform; the most common users there are tourists and others enjoying the vistas.)
  • Not only do the frequent users deserve consideration — they also make the parks safer for everyone by their presence. The natural areas of the city are not over-used, they are under-populated. On a trip to Bayview Hill one weekday afternoon, we encountered one other person in one hour — a dog walker. In Mc Laren Park — about four. Also dog-walkers.

These are uses that a focus on native biodiversity could severely constrain. The San Francisco Sierra Club’s Yodeler magazine carried a reaction to the Recreation and Open Space Element of the city’s plan. Here’s what it said about recreation: The draft ROSE talks about the benefits of open space for physical fitness through exercise and recreation, but these one can do on city streets or in gyms. Back in 2009, we reprinted an article on “Museumification” in two parts  (here and here). This is the process of making public lands into plant museums that discourage or prohibit recreational uses, via restorations favoring “native biodiversity.”


In the search for “biodiversity” (i.e. native plant biodiversity) there’s little focus on ecological function of the “non-native” elements of the ecosystem. It’s usually an article of faith that somehow, a native eco-system is better — even when it’s evident that the non-native plants are important to the habitat. They also increase biodiversity. In a recent talk, Peter Kareiva, chief scientist at the Nature Conservancy, pointed out that California’s plant species had increased 25% because of introduced species.

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2 Responses to San Francisco, Biodiversity, and the Department of the Environment

  1. milliontrees says:

    Science does not measure biodiversity solely by counting native species. Most scientific studies use the Shannon-Weiner diversity index which ranges from zero for a community with only one species, to values of seven or more in some rich western forests.

    In “Historical vegetation change in Oakland and its implications for urban forest management” by David Nowak (USDA Forest Service), the author reports that the Shannon-Weiner tree diversity index value in Oakland prior to urbanization was only 1.9, reflecting a narrow range of biodiversity. Mr. Nowak estimates that the tree diversity index in Oakland in 1988 was estimated at 5.1.

    In “Equal diversity in disparate species assemblages: a comparison of native and exotic woodlands in California” by Dov Sax (Brown University), the author used the Shannon-Weiner index to compare species diversity in 3 hectares of eucalyptus forest with 3 hectares of oak-bay woodland in Berkeley, California. He concluded, “Species diversity patterns (using the Shannon-Weiner Index) were qualitatively identical to those for species richness, except for leaf-litter invertebrates, which were significantly more diverse in eucalypt sites during the spring.”

    San Francisco’s Commission on the Environment is not a scientific organization. It is a political organization with political objectives that are often unrelated to science. The Natural Areas Program will not produce greater biodiversity in San Francisco. It will reduce biodiversity and it will do so by using a lot of herbicide that will also damage the environment. The Commission on the Environment is misnamed. .

  2. Pingback: Measuring Pesticide Use by San Francisco’s Natural Areas Program | Save Mount Sutro Forest

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