Wildfire literature has overwhelmingly supported the need for Zone 0 (the 0-5 ft zone around a hose) as proposed by IBHS, CalFire, and many fire departments around the nation [the general recommendation is to remove all vegetation except for taller trees in Zone 0].
The only research paper used by opponents of Zone 0 has been the 2019 Syphard and Keeley paper titled Factors Associated with Structure Loss in the 2013–2018 California Wildfires [others are non-research papers such as letters or magazine articles]. Despite detailed critiques that show that it cannot actually be interpreted in this manner, it has been widely in social media as “evidence” that Zone 0 ordinances are not science-based.
We just became aware of a document, addressed by Dr. Alexandra Syphard to Chief David Winnacker, a well-known expert in wildfire mitigation, stating that she supports Zone 0 regulations, and disavowing the use of her research against Zone 0.
Her explanation as to why her paper(s) cannot be used for that purpose:
“The study in which I recommend that excessive defensible space may not be needed is specifically talking about those who want to far exceed the 100’ minimum, or those who want to moonscape their property and thus invite ex[c]essive colonization by un-irrigated invasive annuals (a concern most relevant to southern CA).”
How she expresses her support for Zone 0:
"I am sorry to learn that my work is being somewhat misrepresented in a way that could make residents more at risk to wildfire. […]
My study found significant benefits of defensible space, particularly the closer you are to the structure. It is my thought that the Zone Zero requirements are one of the most important things residents can do to protect their property from wildfire.
Studies that show a relatively larger effect of construction materials should not be taken to mean that defensible space should not be done or that it will not have benefits. This is particularly the case for Zone Zero, but it is also important to maintain 100 feet of appropriate defensible space (i.e., according to Cal Fire guidelines) for firefighter safety and maneuverability."
The other author, Jon Keeley, has also sent comments to Berkeley Chief Arnold. Here are some excerpts that regard Zone 0:
" Although our research has not dealt with the Zone 0, what I have learned from a number of sources including CAL FIRE is that hardscaping the first 5’ around homes has the potential for reducing home losses. Demonstrations have shown this is likely a valuable way to reduce home losses, though I understand to some this may not be aesthetically pleasing. I offered the view often expressed by J. Lopez in talks he has given, “position plants so they can be viewed from the kitchen window”, ie not directly under the window. Beyond 5’ there is need for vegetation treatments though the word ‘clearance’ is unfortunate because simulation models have shown complete clearance is not needed but rather adequate spacing and trimming of vegetation will suffice.
Our research has examined a large number WUI fires and found that fuel treatments up to 100’ from a house can have a statistically significant positive impact on home survival. There is a common belief that ‘more is better’ yet our research has found no evidence that vegetation treatments beyond 100’ have any positive effect on home survival. To date I don’t know of any research that supports the idea that vegetation treatments beyond 100’ has a positive effect and so it would appear that treatments beyond 100’ lacks a sound scientific basis."
Dr. Alexandra Syphard letter in toto
I am sorry to learn that my work is being somewhat misrepresented in a way that could make residents more at risk to wildfire.
The study in which I recommend that excessive defensible space may not be needed is specifically talking about those who want to far exceed the 100’ minimum, or those who want to moonscape their property and thus invite ex[c]essive colonization by un-irrigated invasive annuals (a concern most relevant to southern CA).
My study found significant benefits of defensible space, particularly the closer you are to the structure. It is my thought that the Zone Zero requirements are one of the most important things residents can do to protect their property from wildfire.
Studies that show a relatively larger effect of construction materials should not be taken to mean that defensible space should not be done or that it will not have benefits. This is particularly the case for Zone Zero, but it is also important to maintain 100 feet of appropriate defensible space (i.e., according to Cal Fire guidelines) for firefighter safety and maneuverability.
I would put less weight on the defensible space measurements in the 2019 paper because we did not measure defensible space ourselves.
Please let me know if there is anything else I can do to help.
Alexandra D. Syphard, PhD
References