Cutting trees wont help us live with fire
Cutting trees wont help us live with fire
13 October 2016
published by http://www.sfchronicle.com
USA Californians will always have to contend with fire. Our landscape evolved over millennia to be fire dependent. Historical planning and building practices, decades of wildland fire suppression, and now climate change have increased this danger, yet many of us have chosen to live in or near the wildland urban interface. There are very practical steps that can be taken to increase the odds that your home and neighborhood will survive a wildland fire. Cutting down the trees in our urban forests is not one of them.
After environmentalists successfully sued in federal court, the Federal Emergency Management Agency last month rescinded a $5.67 million grant to East Bay officials for an enormous project to remove groves of eucalyptus trees in the Oakland Hills. This was a controversial proposal to reduce fire hazard in an area swept by a firestorm 25 years ago that destroyed more than 3,000 homes, killed 25 people and injured 150. The community divided over the proposals wisdom and efficacy.
Although not easily ignited, eucalyptus trees can burn with intensity under the right conditions. This is also true of other tree species. Dry grasslands, shrubs and other fuels are easily ignitable, burn quickly and spread fire rapidly. We cant remove fuel from the equation unless we pave the hills and thats not a good plan.
Trees are essential to our survival on Earth. Deforestation is a major driver of climate change. Eucalyptus trees provide valuable habitat to bees, monarch butterflies and raptors. They may be one of the few tall tree species able to survive prolonged California droughts. Indeed, removal of a tree canopy increases fire risk through the loss of natural fire retardants: cooling shade, moisture captured from fog drip and windbreaks.
Investigations by fire scientists have led to the conclusion that fire behavior, even very intense fires, outside the limits of defensible space has little bearing on whether homes burn. (Defensible space refers to clearing grass and brush up to 100 feet around any structure.) Even within these areas, experts dont advise cutting down live, healthy trees. Spending millions of tax dollars to remove hundreds of thousands of trees in parks and public lands is destructive, misguided and wasteful.
Thirty years of research on fire behavior at the U.S. Forest Services Missoula Fire Sciences Laboratory has led cutting-edge fire scientists such as Jack D. Cohen to identify the problem as homes, not trees. Houses ignite because burning embers land on horizontal combustible surfaces wood roofs and decks, or roofs and gutters filled with fine fuels such as pine needles and leaves, or combustible material and objects left within 5 feet of a house.
A smarter strategy for hazard reduction than cutting down trees is to learn lessons from how we approach another local natural hazard: earthquakes. We cannot control nature, but we can find ways to live here that improve our survival odds. Over the decades we have retrofitted many of our buildings to be more earthquake resistant. We need to do the same for fire prevention.
Building codes now require that new houses in the wildland urban interface areas be built to resist fire, but this doesnt apply to existing buildings. Why not fund public policy initiatives to retrofit buildings instead of cutting trees? How can we encourage homeowners to voluntarily remodel highly combustible houses in high hazard areas to become ignition resistant?
Yes, wildland fires are frightening, but residents are not powerless. We can choose to manage this challenge safely. We all must take responsibility for doing our part: fixing and maintaining our homes and neighborhoods. If we fail to act, repeated and destructive fires will do the fixing for us.
Marg Hall of Berkeley had more than 30 years of work experience as a carpenter, building inspector and civil engineer. To comment, submit your letter to the editor at http://bit.ly/SFChronicleletters.
