California: A State of Change

Laura Cunningham’s book, A State of Change*  is a remarkable achievement, reflecting a lifetime of observing nature, informed by formal training in paleontology and biology and finally depicting that knowledge in oil paintings of the historical ecology of California. 

Ms. Cunningham introduces her theme with the title of her book.  California is the state that changes and is always in a state of change.  She acknowledges the physical forces of geology and climate as well as the biological interactions of plants and animals as she describes the dynamic qualities of nature.  She treats the complexity of these interactions with respect, frequently declining to reach conclusions because of the speculation that would be required to do so. 

Although we will touch on just a few themes of her book which are relevant to the mission of the Million Trees blog, we encourage readers to give this book the complete read it deserves. 

Sustainability of native plant gardens

Site of the El Cerrito Plaza with the Albany Hill in the background, centuries ago. Oil painting by Laura Cunningham, with permission

Ms. Cunningham tells the charming story of her first experience with native plant restorations as a teenager in the hills of Berkeley/Richmond in the mid-1980s.  With her parents’ permission, she dug up the lawn in their backyard so that she could plant native grassland.  She started with the seeds of native grasses that she collected locally and later transplanted native bunch grasses from nearby properties slated for development.  After several years of regular weeding and new planting, her small plot resembled the grassland she had envisioned.

When she finished her education at UC Berkeley and began to work further away, her grassland slowly succeeded to shrubs and non-native plants, a process she describes as follows: 

“Visiting deer brought weed seeds in on their fur, scrub jays planted live oak seeds into the grass, and flying finches dropped the seeds of Himalayan blackberry in the yard.  The latter, a thick, tenacious vine, slowly formed great thickets over the grasses, shading them out in places.  The food web had won, although I had learned a lot in the process.  I dug up the yard again, back to bare dirt, and gave it back to my parents.” 

This personal story is consistent with other local experiences reported on the Million Trees blog:

 Fire Ecology of California

Those who continue to believe that non-native plants are more flammable than native plants should read Ms. Cunningham’s book, which describes at length the important role that fire plays in California’s ecology.  She introduces this topic with the heading, “Chaparral:  Burning Like a Torch of Fat.”  Charcoal deposits in ancient sediments prove that wildfires in California’s brushlands have occurred frequently for hundreds of thousands of years.  Some shrubs, such as chamise, contain resinous leaves that encourage burning.  Others, such as ceanothus and manzanita require the intense heat of a fire to germinate.  Others will germinate only in the ashes of a fire.  As we have said repeatedly on the Million Trees blog, eradicating non-native plants and trees will not eliminate fire from California.

Ms. Cunningham also reports on the modern debate about reducing wildfires in California.  Although we are very familiar with this debate, we have not read so clear a presentation of it as Ms. Cunningham provides. 

One “camp” in this debate believes that the suppression of wildfires in California has resulted in fuel loads that are much greater than in the past and therefore result in bigger, more damaging fires.  This camp believes that fire danger can be reduced by allowing smaller fires to burn and conducting periodic prescribed burns. 

The opposing view is that fire suppression has been largely unsuccessful and therefore fuel loads are not substantially greater than they were historically.  Wildfires are attributed to hot, wind-driven fire in which fuel load is irrelevant; that is, everything will burn in a wind-driven fire.  Although this is the historical fire regime, fires are causing more loss of lives and property in modern times only because of the development of residential communities in the wildland-urban interface.  This camp therefore sees no point in prescribed burns and proposes to reduce risk to lives and property by limiting residential developments in wildlands and creating defensible space around residences by eliminating most vegetation. 

With humility, Ms. Cunningham declines to choose a side in this debate, acknowledging there is much compelling evidence to support both views. 

The Million Trees blog prefers the theory that wildfires are caused by hot winds rather than accumulated fuel loads because our perspective is limited to the San Francisco Bay Area.  We don’t think prescribed burns are appropriate in a densely populated urban setting where both pollution and risk of wildfire are major concerns.  And, based on our local experience, the only fires that have become raging wildfires are those that were wind-driven.   We advocate for reducing fire hazards by creating defensible space and routine maintenance of flammable vegetation litter.   

Historical Ecology

San Francisco 500 years ago, looking eastward from the top of Nob Hill. Oil painting by Laura Cunningham, with permission

We are grateful to Ms. Cunningham for giving us permission to publish two of her historical paintings of California.  These paintings enable us to confirm that trees were not a conspicuous part of the landscape of the Bay Area.  The dominant landscape was grassland and shrubs.  Although there may have been more trees if the landscape had not been frequently burned by Native Americans, based on our knowledge of horticultural requirements of native trees, we believe that even in the absence of fire there would have been few trees.  The native trees will not tolerate the wind on the hills of San Francisco.  Even in places where trees are sheltered from the wind, they must have access to sufficient water to become established. 

When native plant advocates demand that non-native trees be destroyed, they frequently claim that non-native trees will be replaced by native trees (even without being planted in some cases).  We assume their claims are based either on strategy (i.e., promising “replacement” trees in order to diffuse the opposition of those who like trees) or on ignorance of California’s natural history. 

With deep respect, we acknowledge Ms. Cunningham’s impressive knowledge of California’s ecological history and the accomplishment which her book represents.  Our thanks to Ms. Cunningham for sharing her lifetime of study and observation of nature with us and rendering that knowledge so beautifully in her paintings. 


* Cunningham, Laura, A State of Change:  Forgotten Landscapes of California, Heydey Books, Berkeley, California, 2010

Creating Defensible Space for Fire Safety

Those who have a sincere desire to reduce fire hazards in the Bay Area would be wise to turn their attention away from the distracting and irrelevant debate about the flammability of native compared to non-native plants and trees.   California native ecology is dependent upon and adapted to fire.  The native landscape is not less flammable than non-native plants and trees.  Most firestorms in California are wind-driven fires in which everything burns, including native and non-native trees and plants as well as any buildings in the path of the fire.   

Rather, the creation of “defensible space” immediately around your home is your best defense against the loss of your home in a wildfire.  Creating defensible space means reducing fire fuels around your home by appropriate pruning and maintenance, such as limbing up trees to remove the fire ladder to the tree canopy and removing leaf litter.  Defensible space is intended to slow the progress of fire to your home.

In this post we will visit several reputable sources of information about fire safety that advise homeowners about how to protect themselves, particularly those who live in the Wildland-Urban Interface where fire hazards are greatest.   We will see that all these sources of information have in common that they do not single-out specific species of plants or trees.  Rather they emphasize that how vegetation is pruned and maintained is more important to reducing fire hazard and that materials we use in building our homes are equally important to our safety.  These sources of information are not native plant advocates.  Their advice is not based on a desire to destroy non-native plants and trees in the belief that their destruction will benefit native plants and trees.  

Firewise Communities is an internet resource provided by the National Fire Protection Association and co-sponsored by the US Forest Service and the US Department of the Interior.  This resource offers on-line courses in fire safety.  In the course on “Firewise Landscaping” these criteria are listed as the characteristics of fire-resistant plants:  low leaf litter, high water retention ability, high salt retention ability, lack of aromatic oils, low fuel volume, height and spread that fits well into the intended space.  Some native and some non-native plants fit these criteria and some do not.  For example, although the leaves of eucalyptus contain aromatic oils, so do the leaves of the native California bay laurel.   

Homeowners in the Wildland-Urban Interface should focus on creating defensible space around their homes rather than on choosing particular plant or tree species. CALFire guidelines for creating defensible space do not advise for or against any particular species of plant or tree. Rather CALFire focuses on how to prune and maintain vegetation around your home and create a “defensible space” around your home with low fuel volume, as illustrated in this brochure on their website.

Creating defensible space around your home. CALFire

Likewise the UC Berkeley Fire Center in their brochure “Home Landscaping for Fire” says, “It is important to remember that given certain conditions, all plants can burn…how your plants are maintained and where they are placed is as important as the species of plants that you chooselandscape management (e.g., pruning, irrigation, and cleanup) have a greater impact on whether or not a plant ignites than does the species.” It is ironic that UC Berkeley is engaged in the destruction of every non-native tree and plant on its property, despite the advice on its own website about fire safety, which is obviously being ignored. 

The August 2010 issue of Sunset Magazine includes a comprehensive “Wildfire Survival Guide,” including advice about planting a fire-safe garden. 

The City of Oakland passed an ordinance in 2006 requiring homeowners to maintain defensible space around their homes and voters in Oakland agreed to tax themselves to pay for the enforcement of this requirement.  Unfortunately, a drive in the Oakland hills informs us that these requirements are not being enforced. 

Oakland hills

This home is particularly vulnerable because fire tends to travel up hill.  Firewise says that a 30% slope will accelerate the rate of spread of fire to twice the speed of fire on flat ground. 

Wouldn’t the people of Oakland be better served by enforcement of requirements for defensible space around homes rather than paying shared costs of $662,280 for a FEMA grant to eradicate all non-native vegetation from 325 acres of wildland? (see “Our Mission, Projects in the East Bay”)  Oakland is  flat broke and one of the most violent cities in the country.  Eighty policemen were recently laid off and 120 more are likely to be laid off if voters don’t vote to tax themselves further.  Shouldn’t homeowners be required to create defensible space around their homes where their lives and property are most at risk before “vegetation management” is extended far beyond the perimeter of homes?