Creating Tree Graveyards in San Francisco

At 13.7% of tree canopy coverage, San Francisco has one of the smallest tree canopies of any major city in the country.  When San Francisco’s Urban Forestry Council (UFC) announced its goal of planting 30,000 new street trees in the next 20 years, it seemed a modest goal.  Yet, Jake Sigg, the leader of native plant advocates in San Francisco, immediately objected to even this modest goal in his Nature News.  He announced the meeting of the UFC to consider the proposal and pronounced it a bad idea:

“JS:  Let’s start taking climate change seriously.  There is a prejudice—it is nothing more than that—that trees sequester more carbon than other life forms.  That is a simplistic view that, when looked at more closely, is found wanting.  To counter climate change we need to remove carbon from the air and put it where it will be for a millennium or more.  Removing it for a few decades or a century is pointless. 

“There are many reasons to plant trees on San Francisco streets, and many of our streets need them.  Climate change is not a stand-alone phenomenon; it is intimately related to diversity of biological elements.  That argues for planting native plants to invite dispossessed wildlife back into the city and you do that by planting the plants they need.  There are trees, shrubs, and perennials that ought to line our street to function in this way.  Carbon removal should not be a factor in our street plantings—biodiversity should be Number 1.”

Jake Sigg, Nature News, July 2, 2022

Yes, Jake, biodiversity is important because a diverse ecosystem is more resilient in a changing climate, but destroying all non-native plants does not make an ecosystem more diverse.  Climate change is the greatest long term threat to biodiversity, which makes addressing climate change a prerequisite to preserving biodiversity. 

I attended the Urban Forestry Council meeting of July 5, 2022, when this proposal was considered.  I was expecting to hear objections from Jake Sigg’s followers. Instead, the handful of written public comments objected to the meager commitment to plant only 30,000 new trees in San Francisco in the next 40 years. I learned more about the plan to plant more street trees in San Francisco:

  • There are presently an estimated 125,000 street trees in San Francisco.
  • Because the mortality of street trees is high, the expectation is that 50,000 street trees would need to be planted in the next 20 years to replace dead street trees.
  • According to the Urban Forestry Council it costs $1,500 to plant a tree and an additional $2,500 to water it for three years until it is established.
  • 4,000 trees would need to be planted every year to keep pace with expected tree mortality and to add 30,000 more street trees. 

These goals exist only on paper.  Between 1,500 and 2,000 trees per year are being planted in the city and no funding has been identified to increase this number.  After delivering this bad news about the sorry state of San Francisco’s urban forest, one member of the UFC spoke some much needed common sense.  Nicholas Crawford said we should “hold onto shabby trees” that are established and storing carbon.  He suggested that San Francisco should not remove trees that are at least stable because there are no trees to replace them. 

Existing trees in our urban forest are more valuable than ever.  They are storing more carbon than a replacement tree will store for at least 20 years.  They don’t need to be irrigated because they have the root and fungal networks needed to supply the tree with the moisture it needs.  Existing trees have proven themselves.  The fact that they are alive and well after 10 years of extreme drought proves they are adapted to current climate conditions.  So why destroy them? 

Jake Sigg acknowledged the value of forests to address the challenges of climate change in a recent newsletter:  “In order to have an impact on climate we need to stop deforestation and preserve, strengthen, and restore what is already here.” (Nature News, July 6, 2022)  But that principle does not apply to San Francisco for Sigg and his followers because the trees of San Francisco are predominantly non-native and they place a higher value on restoring pre-settlement treeless grassland and coastal scrub.  Because of the power and influence of the native plant movement in San Francisco our urban forest is being destroyed and planting trees is resisted.

San Francisco has made a commitment to destroying more than 18,000 non-native trees in San Francisco’s public parks.  The stated goal of that program is a landscape of native grassland and scrub.  UC San Francisco has also made a commitment to destroy most of the non-native forest on Mount Sutro.  Thousands of trees have been destroyed on Mount Sutro and more will be destroyed in the future.  The Executive Director of Sutro Stewards, the non-profit organization that is implementing the plans for destruction of the non-native forest on Mount Sutro is represented on the Urban Forestry Council, an odd choice for a citizen’s advisory council theoretically committed to the urban forest.

Tree destruction on Mount Sutro, January 2021.  Courtesy San Francisco Forest Alliance

McLaren Park:  A Case Study

Today Conservation Sense and Nonsense will visit a relatively new project in McLaren Park that has destroyed non-native trees in order to create a small native plant garden.  We drill down into the project to understand why San Francisco’s urban forest is being destroyed.  We visit this project because it is an example of many similar projects that are planned in San Francisco. 

This is one of many attempts to plant native plant gardens on Sunset Blvd in San Francisco. The functional windbreak of Monterey cypress is dying of old age. Rather than replace the windbreak, native shrubs are being planted on Sunset Blvd that will not function as a windbreak in the windiest district in San Francisco. The lack of maintenance that you see here is typical of these gardens, which makes them unpopular with neighbors.

At 312 acres, McLaren Park is one of the largest parks in San Francisco.  Fifty-three percent (165 acres) of McLaren Park is designated as a “natural area,” which means that a commitment was made nearly 25 years ago to transform it into a native plant garden.  The new native plant garden that we visit today is not actually inside one of the designated “natural areas.”  The reach of the native plant movement in San Francisco extends far beyond the 1,100 park acres of “natural areas” that were claimed in 1998. 

The new native plant garden is located in the southeast corner of McLaren, south of the community garden at the intersection of Visitation Ave and Hahn St.  This is a photo of some of the trees that were destroyed to create the native garden:

©Lance Mellon with permission.  July 2020

And this is a photo taken in December 2021, after the trees deemed “non-native” were destroyed:

© Lance Mellon with permission

The plans for the native plant garden say that 18 non-native trees would be destroyed and 6 native trees would be retained.  The plan claims that tree removals of all non-native trees were based on “professional assessments.”  Such “assessments” are routinely used by the Recreation and Park Department to justify the removal of non-native trees.  Photos of the trees indicate otherwise.  Retention of only native trees suggests that assessments aren’t even-handed.  The claim does not pass the smell test. 

Plans for the native plant garden indicate that more native trees will be planted:

The trees will need to be irrigated for at least 3 years to establish their root systems and ensure their survival.  The entire garden will need to be irrigated if it is to survive.  Let’s be clear:  an established grove of trees with an understory of annual grasses that did not require irrigation or maintenance was destroyed and replaced with new plants and trees that will require irrigation.  Is that a suitable use of scarce water resources during an extreme drought that is expected to get worse, if not be a permanent change in the climate?  That is the question we consider today.

About 9 months later, the “native plant garden” looks more like a tree graveyard:

McLaren Native Plant Garden, July 2022
Some of the newly planted trees are holly leaf cherry. Signs on the trees indicate that the project was paid for with a CAL FIRE grant. One wonders how a garden full of dead wood is less flammable than a garden full of living trees.

Granted, the native plant garden is likely to look better as plants grow.  However, it will only look better if it is irrigated and taken care of.  Why should we expect it to be taken better care of than the existing garden that required no maintenance?  Wishful thinking will not make it so.

The death grip of nativism

Climate change is the environmental issue of our time.  We are seemingly incapable of doing anything substantive to address climate change.  Political gridlock prevents us from controlling the greenhouse gas emissions causing climate change.  The Supreme Court recently ruled that the Environmental Protection Agency does not have the authority to regulate polluting emissions from power plants. 

We focus on the preservation of our forests because it is the only tool we have left to absorb carbon emissions from the fossil fuels to which we are wedded.  Native plant advocates have taken that tool away from us.  Our urban forests are being destroyed and replaced with grassland and scrub.  Claims that grassland and scrub store more carbon than forests are ridiculous.  Those claims earn native plant advocates the label of climate change deniers.  As the drought continues to plague California, established landscapes that required no water are being destroyed and replaced with native plants that require irrigation.