Ecology – Page 45 – Conservation Sense and Nonsense

KILLER TREES!!! Scare Tactic #3

We have recently learned of another tree removal project in the Bay Area. In this case, the San Leandro Creek Tree Management Project by the Alameda County Flood Control & Water Conservation District proposes to destroy about 50 eucalypts in the short run and approximately 1,000 more in the long run. All eucalypts will be removed. All other species of trees will remain.

St. Mary’s Ave: Try to picture this neighborhood without any of the tall trees in the background.

In this case the apparent “cover story” for yet another native plant restoration is that the trees are hazardous. As we have said in other posts, native plant advocates have had difficulty convincing the public—and therefore their political representatives–of the need to destroy non-native trees and plants and so they have frequently resorted to scary cover stories. Particularly in the East Bay, the most powerful argument has been the claim that the trees are flammable. The argument heard more commonly in San Francisco, where there is no history of wildfire, is that the trees are invasive and are killing native plants. Fortunately, there is scientific evidence that these claims are not accurate.

Native plant advocates also claim that eucalypts are more dangerous than other trees. However, the public record indicates that every species of tree—both native and non-native—can fall. The most recent “death-by-tree” in San Francisco occurred on April 14, 2008, when a visitor to Stern Grove was killed by a huge branch from a Redwood tree that had been judged to be hazardous by a certified arborist 5 years earlier. Unfortunately, the arborist’s report was ignored, resulting in the needless death of a young woman in the prime of her life. The City of San Francisco paid her family $650,000 for their negligence…a waste of a life and the taxpayer’s money for a death that could have been easily prevented.

Tragic events such as this make it clear that we should not oppose the destruction of hazardous trees. Unfortunately, that is a judgment that is not clear-cut or irrefutable. When native plant advocates demand the destruction of non-native trees, we are deeply suspicious of the claim that the trees are hazardous. In the case of the San Leandro Creek project, it is simply not credible that every eucalyptus is hazardous, but not any other species of tree in the watershed.

After many years of being put in the awkward position of evaluating the truth of such claims, we have concluded that we trust only the judgment of certified arborists, but not those paid to destroy the trees. There are a handful of arborists whom we know not to be biased against non-native trees, especially eucalypts. If we are told by these arborists that a particular tree is hazardous, we accept that judgment.

The neighbors of the San Leandro Creek who were about to lose many of the trees they love, organized and fought back. They protested the removals not just because they love their trees, but also because the project was invisible to them until the Alameda County Flood Control & Water Conservation District granted itself a categorical exemption from California Environmental Quality Act (CEQA) requirements for an environmental review. Short of a legal suit there was little that could be done to stop the project except scream. So, that’s what they did.

What is unique about this project is that the neighbors have prevailed. For the moment, it appears that this project has been halted. The Flood Control District has apparently agreed to step back, start over, and involve the neighbors before implementing their plans. We should all learn from this experience. We must speak up for our trees when they are threatened with needless destruction.

Million Trees usually reports such projects directly from the public record. In this case, we have access to little of the public record. We have asked the Water District’s representative for answers to many questions about this project, but have not received answers. We are therefore reporting based on what little documentation is available on line, reports of the neighbors, and one media report . We invite any needed corrections to this report and we will correct any errors, based on verifiable documentation.

Update: We are pleased to tell you that this controversy was finally resolved to the satisfaction of the neighbors of San Leandro Creek. Neighbors forced the county to do another evaluation of the trees in the creek. As a result, plans to destroy as many as 1,000 eucalyptus trees were finally reduced to a total of 17 trees deemed hazardous.

Glen drive comparison — Glen Drive: What will this property be worth after the tall trees are removed? Significantly less.

ALIEN INVADERS!!! Another scary story about non-native trees

As we have said before in “FIRE!!! The Cover Story,” fear is a powerful motivator of public policy. The fear of fire is not the only tool in the toolbox of native plant advocates. They would also like the public to believe that non-native plants are invasive, that they will overwhelm the environment if they are not promptly eradicated. So, we will take a closer look at this claim and show that non-native trees are not invading Bay Area open spaces.

In “Vegetation Change and Fire Hazard in the San Francisco Bay Area Open Spaces,” William Russell (USGS) and Joe McBride (UC Berkeley) used aerial photos of Bay Area parks taken over a 60 year period from 1939 to 1997, to study changes in vegetation types. They studied photos of 3 parks in the East Bay (Chabot, Tilden, Redwood), 2 parks in the North Bay (Pt Reyes, Bolinas Ridge), and one on the Peninsula (Skyline).

These photos revealed that grasslands are succeeding to shrubland, dominated by native coyote brush and manzanita. Eucalyptus and Monterey pine forests actually decreased during the period of study. In those cases in which forests increased in size, they were native forests of oaks or Douglas fir. In other words, they found no evidence that non-native trees are invading native trees or shrubs.

They also studied the implications of these changes in vegetation types for fire hazard by measuring surface biomass for each vegetation type as an indicator of fuel load and by using a computer model (FARSITE) to simulate the speed of spread of a fire. They concluded,

“A significant increase in the cover of shrublands was apparent in the general analysis…The results from the fuel and fire hazard analysis suggest that the succession from grasslands to Baccharis [coyote brush] shrublands indicates dramatic increase in fire hazard for those areas. Fire line intensity, flame length, and total biomass were found to be significantly higher with the shrub dominated areas. In the context of the landscape matrix as a whole this increased hazard indicates a greater possibility of fire being spread into adjacent forested areas and residential communities.”

This is a view of one of the "recommended treatment areas" in the East Bay Regional Park District's "Wildfire Plan" in Anthony Chabot Park. In the foreground are many acres of coyote brush that are about six feet tall. The plan does not propose any "treatments" in these acres of highly flammable coyote brush. In the background is the eucalyptus forest that will be thinned in some places and removed in others. This is not a plan that will reduce fire risk.

This study, based on actual aerial photos, tells us that native shrublands are increasing in size while non-native forests are actually decreasing in size. It also tells us that this succession of vegetation types from grassland to native shrubland is increasing fire hazard. There is no evidence that non-native forest is invading the open spaces of the San Francisco Bay Area. The public has no reason to fear that non-native trees will overwhelm our environment.

Common Characteristics

Native plant advocates attempt to support their claim about the flammability of eucalypts by citing specific characteristics such as shreddy bark and volatile oils. Shreddy bark and volatile oils are characteristics of many plants, both native and non-native. They are not characteristics exclusive to eucalypts:

“The [chaparral] community has evolved over millions of years in association with fires, and in fact requires fire for proper health and vigor…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.” (page 341, A Natural History of California, Schoenherr, UC Press, 1992)

Madrone and Manzanita are examples of native plants with “ribbonlike shreds on the bark” that are highly flammable. Coyote brush and bay laurels are examples of native species which contain highly flammable oils.

Anyone with knowledge of the natural history of California could provide any number of such invidious comparisons between native and non-native plants with respect to their flammability. We hope the examples we have provided illustrate that flammability characteristics of plants are unrelated to whether the plants are native or non-native. The claim that non-native plants are more prone to fire than native plants is fallacious.