Protecting Our Communities from Wildfire: 2 STEPS
The HCN, created after the catastrophic 1991 Hills fire decimated our East Bay hills neighborhoods, remains dedicated to our core mission: protecting our communities from another wildfire disaster. To do so, we continue to research and promulgate the latest studies and science on wildfire behavior, neighborhood preparedness, and wildfire home protection. READ WHAT WE'VE ACCOMPLISHED.
A majority of our East Bay hills neighborhoods are in, or near, forested areas which inherently have more wildfire risk than urban areas. (Fire agencies call neighborhoods like ours Wildland Urban Interfaces, or WUIs). Fortunately, wildfire research and science have advanced considerably, and there are many actions we can take, both individually and as communities, to dramatically reduce wildfire danger and protect our homes and neighborhoods.
How did this house survive a forest fire burning all around it?
The first line of defense, endorsed by fire science and firefighting agencies, is
to create "Defensible Space" — a term you're likely familiar with — around
your house and other structures on your property. Doing so will protect it from
ignition from a nearby wildfire, especially from airborne embers, what fire
scientists call "firebrands." READ MORE ABOUT Defensible Space.
Thousands of firebrands — or hundreds of thousands of firebrands — that land
on roofs, in gutters, under eaves, and into dried grasses are responsible for 50%
of home ignitions during wildfires, not the heat or direct contact with flames.
Jack Cohen, Ph. D., is Physical Research Scientist who worked for years for the Fire Labs research station
of the Forest Service (a division of the USDA). He is one of the most prominent and respected wildfire science researchers in the field. Cohen's over 30 years of ground-breaking work is now widely accepted by professionals
in the field of fire science in the U.S. & abroad and endorsed by the NFPA (National Fire Protection Association).
Cohen coined a term you are likely not familiar with, referring to the area closest to your house and other
structures on your property: the "Home Ignition Zone."
The “Home Ignition Zone” (HIZ)
includes your house and the area up to
100 feet outward. There are many straight-
forward, commonsense, easily implemented
treatments you can make within the HIZ to
dramatically increase the "ignition-resistance"
of your house, decreasing the chances your
house will be ignited by a wildfire, especially
by a wildfire's shower of thousands of airborne
Firebrands are by far the most common
cause of house ignitions in a wildfire,
responsible for over 50% of them.
Firebrands can be windblown great distances (over a mile) by a large fire, raining down on houses and property, igniting the most flammable materials referred to as "fine fuels," like dried leaves and pine needles on roofs or in gutters, and in dried grasses or shrubs which can in turn ignite larger flammable materials — and houses.
Inspecting for, and simply removing these “fine fuels” on and around your house during fire season can dramatically decrease the likelihood your house or property will ignite in a wildfire. To repeat a key point, 50% of homes destroyed by wildfires are ignited by firebrands which ignite fine fuels in the Home Ignition Zone, NOT direct flames from a fire.
READ MORE about The Home Ignition Zone
A “Community Protection Zone” (CPZ) protects groups of houses and structures — an entire neighborhood — from an advancing wildfire front with a single swath, or band, of reduced vegetation adjacent to the neighborhood, or between the neighborhood and an adjacent forest most likely to be the source of a fire. Its placement and boundaries are determined by assessing numerous factors including topography, prevailing winds direction, vegetation, forests, and the direction from which a wildfire is most likely to advance. (See example in diagram below.)
A CPZ gives firefighters additional options and access where none exists, especially near forests. Some existing paved roads and dirt fire roads already serve this function, enabling firefighters the only quick access to otherwise inaccessible areas. A CPZ can act as a "safety zone" from which firefighters can stage efforts against an advancing fire (see diagram), helping prevent a fire from entering a neighborhood . Thus, a CPZ can reduce the possibility of ignition of houses from direct contact with the flames of an advancing forest fire.
NOTE: A Community Protection Zone is an important supplemental treatment, but is NOT a replacement for individual homeowners treating their own houses' Home Ignition Zones (HIZ) which dramatically reduce firebrand ignitions even if firefighters are successful in using a CPZ to prevent a wildfire's flame front from entering a neighborhood.
A detailed description of how a CPZ adds additional wildfire protection to neighborhoods is in a research paper by
Brian Nowicki, "The Community Protection Zone: Defending Houses and Communities from the Threat of
Forest Fire," published by the Center for Biological Diversity. Excerpt below. READ PAPER (PDF at right).
Creating a CPZ does NOT require removing all trees in the area, only thinning some to create breaks in the continuity of tree crowns and reducing some understory ladder vegetation which can ignite crown fires. In fact, retaining large trees is critical as they perform multiple wildfire-suppressing functions: as windbreaks, blocking the heat of a fire, and suppressing understory growth like ivy, thistle, grasses, shrubs that spread fire more quickly than mature trees do. READ MORE.
Why not just cut down more trees around our houses, and in the hills? Wouldn't that make us all safer from wildfire?
At first glance, this might seem reasonable, or even necessary, but the science doesn't bear this hypothesis out — nor do the experiences of recent 2018 and 2019 California wildland fires. In both northern and southern California, heat, aridity and high winds drove fires rapidly through grasses and chaparral. Trees burned too, of course, but didn't start the fires, nor spread them as quickly as the finer, fast-burning grasses and chaparral did, and do. READ ABOUT GRASSLAND FIRE DANGER.
In fact, "thinning" forests, or cutting them down, merely exchanges one type of wildfire risk for another. Cutting down large numbers of trees reduces the fog creation and cooling shade of forest canopy. And increases winds in an area; winds which drive California's recent, uncontrollable fires. Finally, removing large numbers of trees results in understory growth, adding more fuel for a fast-moving, wind-driven grasslands fire.
“The danger from wildfires is real, but cutting down more trees is not the solution.
By far the most effective way to prevent damage is to focus on the basic fire-safety
measures for at-risk houses. These include installing fire-resistant roofing, ember-proof
exterior vents and guards to prevent wind-borne embers from igniting dry leaves and pine
needles in rain gutters and creating “defensible space” by reducing combustible grasses,
shrubs and small trees within 100 feet of homes.”
- Chad T. Hanson, Ph.D. fire ecologist / Michael Brune, Sierra Club Exec. Director
The New York Times, Sept. 4, 2018
“Removal of the eucalyptus overstory would reduce the amount of shading on surface
fuels, increase the wind speeds to the forest floor, reduce the relative humidity at the forest
floor, increase the fuel temperature, and reduce fuel moisture. These factors may increase
the probability of ignition over current conditions.“
- U.S. Forest Service, Adaptive Management Services Enterprise Team (AMSET). Sept. 27, 2013
We know that the majority of our East Bay (and Bay Area) neighbors love living surrounded by the beauty that trees, forests, wildlife provide. Un-managed, wild nature enriches our lives in countless ways, as well as providing wildlife habitat, lowering neighborhood temperatures, increasing moisture — and even adds to critical global cooling. (Communities in nature also have lower crime rates than urban ones. Among the myriad reasons cities plant trees is the calming effect trees have on humans.) Proximity to nature, being surrounded by trees, forests and wildlife, is a key reason to live in the East Bay hills; transforming houses into our cherished homes.
In 2020 and beyond, anthropogenic climate change is increasing the temperatures and duration of our Bay Area summers and autumns, thus lengthening our dry fire season. Fortunately, we know much more than we did in 1991, when HCN was created, about: 1) the causes of wildfire and; 2) proven methods, endorsed by fire management agencies, to dramatically reduce the danger wildfires pose houses in our forested neighborhoods.
Combining these two treatments programs: Community Protection Zone creation for neighborhoods of houses, and Home Ignition Zone preparations at each house — we can dramatically increase protection from wildfire in all our communities.
In fact, local agencies and municipalities have come to accept this doctrine and have increasingly incorporated it in their fire risk mitigation strategies. What HCN is proposing is to use these methodologies as the core of wildfires risk mitigation and in fact expand the use of these strategies in areas where using roadways as fire breaks is simply not sufficient.
Protect your house from wildfire by creating...
STEP #1 : Defensible Space in the "Home Ignition Zone"
EXCERPT: "In short, a properly implemented homesite treatment provides complete protection for the house; a fireline in the Community Protection Zone can provide additional protection against encroaching ground fires that can ignite houses if the Home Ignition Zone treatment is not properly implemented; and treating the forest beyond the [CPZ] provides no additional protection for houses or communities."
Clearing or "thinning" forests beyond 100 feet from houses does NOT offer significant wildfire protection for houses. Often called "fuels reduction" or "vegetation management" to quell public outcry,
it is misguided, ineffective, and worse, can increase wildfire danger. Numerous studies demonstrate
that the most effective protections are treatments at houses and the immediate surroundings only
up to 100 feet: removing dried materials like leaves, pine needles, and twigs that collect on roofs, in gutters, and next to houses, because these ignite most readily. "Vegetation management beyond the structure's
immediate vicinity has little or no effect on house ignitions." - Jack Cohen & Saveland 1997.*
But creating 100 ft. of Defensible Space at all our houses isn't possible, because they're close to other houses, or to forests.
Instead, we can create defensible space around an entire neighborhood, with
STEP #2 : "Community Protection Zones"