The coast live oak that is native to the Bay Area is one of our favorite trees and we would be happy to see more of them. However, the epidemic of Sudden Oak Death that is killing oaks in California and Oregon makes us question the wisdom of replacing non-native trees with oaks that may not survive that epidemic. Since any dead tree is more flammable than any living tree, we are also skeptical about claims that restoration of the oak-studded grassland will reduce fire hazard in the Bay Area.
The pathogen (Phytophthora ramorum) that causes Sudden Oak Death (SOD) was reported on the UC Berkeley campus in 2002. At that time it also existed at the UC Botanical Garden and the researcher who identified the pathogen speculated that it probably existed throughout the East Bay. By 2008, the SF Chronicle reported that the infestation of SOD existed in several parks in the East Bay. The researcher estimated that about 20% of all coast live oaks in the East Bay are infected with the pathogen that will eventually kill them.
In February 2008, the California Oak Mortality Task Force estimated that ”millions of tanoak and coast live oak” have been killed by SOD in California. Thirty four other species of trees and shrubs are also infected with the pathogen, including bay laurels and redwoods. Although these species are not usually killed by the pathogen they are vectors of the disease. The bay laurel is singled out by the scientific literature as being particularly effective at transmitting the pathogen to the oaks that are then killed.
The “Wildfire Hazard Reduction and Resource Management Plan” of the East Bay Regional Park District proposes to destroy most non-native trees on over 1,500 acres of parkland. The “vegetation management goal” for most of these acres is the restoration of “oak-bay woodland.” And so we ask these rhetorical questions:
- What is the probability that coast live oak will survive the deadly SOD pathogen in the Bay Area?
- Does the proximity of bay laurel to the local oak population increase the probability of infection?
- If the oaks are killed by SOD will the risk of wildfire in the East Bay hills increase?
- If the non-native trees are destroyed and the oaks are killed by SOD will the resulting landscape be entirely treeless?
We believe these are legitimate questions and when we have asked them of native plant advocates we have not heard an adequate answer. We believe that eradicating non-native plants and trees without a clear understanding of the future of the natives, is irresponsible.