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Landscaping can protect homes from wildfire, conserve water during droughts
Published on May 9, 2009 - 8:17:08 AM
By: Center for Fire Research and Outreach at UC Berkeley
May 9, 2009 - The area where homes and landscapes meet wildland vegetation can be a beautiful and quiet place to live. However, the Santa Barbara wildfire is a reminder that this area, commonly called the wildland-urban interface, is also where wildfires pose the biggest risk to people and structures, according to scientists at the Center for Fire Research and Outreach at UC Berkeley.
Wildfires in the wildland-urban interface can spread to landscaping around the home, then to the house. "Ultimately, protecting homes from wildfire requires that material and design features of both the home and near-home vegetation be addressed -- you can't ignore either one" says Steve Quarles, UC Cooperative Extension wood performance and durability advisor in Contra Costa County.
Quarles notes that many homes ignite and are lost because wildfire-generated, wind-driven embers ignite dry vegetation that has accumulated either adjacent to homes or in gutters or on roofs. Overhanging vegetation will facilitate deposition of leaves and needles in these areas. "Make sure you remove these and other wind-blown vegetation debris on a regular basis," Quarles advises. "Embers can also be blown into attics through vents, igniting fine fuels there, or be blown into the home through open windows."
In times of drought, water conservation requirements may lead to landscape vegetation being even more deprived of water, and as a result can make the fire risk higher. Yana Valachovic, UC Cooperative Extension forest advisor for Humboldt County, says, "Implementing well-thought-out fire safety and water conservation techniques, especially during droughts, can be mutually beneficial."
Creating a landscape that results in both fire safety and water conservation can rely on several techniques. For example, plants that have low water needs can be incorporated into your landscape. It is also best to group plants with similar water requirements together. A well designed irrigation system is also essential. In many cases, overhead irrigation can be replaced with drip systems for targeted water delivery. "Your drip system should be inspected and maintained on a regular basis," recommends Sabrina Drill, natural resources advisor for Los Angeles and Ventura counties. "Weed frequently, as weeds compete with your landscape plants for water."
Plant placement is a very important factor in creating a fire-safe landscape. Avoid planting vegetation right next to the home. A fire-safe landscape can be beautiful, provide privacy, and shade. Pay special attention to your landscaping design so that your house is not surrounded by a sea of vegetation. Space individual plants or small groupings so that there is horizontal and vertical separation, so that if one plant ignites, the fire isn't carried to the next plant. "Consider designing your landscaping as a series of 'islands' to break up the connectivity between your landscaping and your home," says Drill. She notes that these islands should be separated with hardscape elements such as patios, walkways or other non-planted areas, or those that involve low-water lawn areas. These areas can also act as fuel breaks.
Mulches have a number of uses in landscaping applications, including erosion, dust and weed control, and reducing soil moisture evaporation from the soil surface. "Unfortunately," says Quarles, "organic mulches -- such as bark, wood and pine needles -- will burn, potentially spreading fire to your home. Because of the combustibility of organic mulches, the predominant desired benefit of the mulch should be balanced with the threat from wildfire." He recommends considering using inorganic mulches near the home, and flammable mulches in other locations. Carefully consider whether to use the more flammable mulches, such as those with hairy characteristics.
Landscape maintenance is vital for both fire safety and drought tolerance. Don't rely on choosing the right species of plant because any plant will burn under the right conditions. Remember that a landscape that is planted correctly when first installed can become a fire hazard if dead material builds up within vegetation.
When inspecting the vegetation around your home, it is helpful to divide the space into two zones -- one near the home (within 30-feet or so) and one that extends outward from 30 to about 100 feet. Be more careful about the condition of the vegetation in the zone closest to your home. What condition is your landscaping in? Is the vegetation green and lush or old and full of dead material? Do you have tree branches near to or over your house? Overhanging vegetation and dead material within a plant would be situations requiring immediate attention.
Tips for water-thrifty landscapes that protect property from wildfire
In times of drought, we are reminded of how flammable plants can be and how vulnerable our houses are to wildfire. A careful review of the construction of a home and its surrounding landscaping can indicate where the most combustible areas are. Water conservation does not necessarily create more combustible vegetation. Through proper maintenance and design, homeowners can simultaneously reduce water use and create beautiful fire safe landscapes.
* Choose plants that are slow-growing and don't produce a lot of dead material.
* "Choose plants that retain moisture (stay green) with little irrigation" recommends Valerie Borel of UC Cooperative Extension. She notes that xeriscaping books have many suggestions of low-water-use plants. Many local Master Gardener programs have information available on low-water-use landscapes.
* Reduce the area of your landscape to fewer plants that are well maintained and healthy.
* Maintain irrigation systems properly -- check them frequently for leaks, and adjust both manual and automatic watering schedules based on the weather and soil moisture.
* Water only as needed to keep plants healthy. "For many woody plants (trees and shrubs), deep and infrequent watering will promote deeper root growth," says Bethallyn Black of UC Cooperative Extension in Contra Costa County. "Deeply rooted plants are more drought-tolerant because they can access water held deeper in the soil." Local Master Gardeners can help determine water requirements.
* Keep trees and shrubs healthy by pruning and removing dead growth. The goal is to maintain an open growth form.Use mulch as needed to perform one of their beneficial landscaping functions (i.e., retain soil moisture and limit erosion). "Many organic mulches are fine from a fire safety perspective if they are kept more than 5 to 10 feet from the home -- gravel (inorganic) mulches can be used in these locations" notes Sabrina Drill. Some jurisdictions restrict use of combustible mulches in the zone within 5 feet of the home, and limit their use to well-spaced 'islands' within 30 feet of the home. You should check with your local fire department to see if any special restrictions apply. Generally mulch should be 2 to 4 inches deep. Needle mulches or mulch having fine hairy components should be avoided as they readily ignite. "Rubber mulches should be avoided in wildfire prone areas," Steve Quarles advises.
* Weed often to reduce competition with plants for limited water. Mulches can be used to inhibit weeds. Group plants together that have similar water requirements. "Allow wide enough between-plant spacing to avoid 'fuel ladders' that enables fire to spread upward into taller shrubs or tree canopies," recommends Glenn Nader, UCCE advisor for Sutter, Yuba and Butte counties.
* Individual plants that are both fire-resistant and drought-tolerant have the following characteristics:
- Produce limited dead and fine material
- Retain high moisture content with limited watering
- Have a low and open growth form
- Have low levels of volatile oils and resins
Web-based resources:
For information on fire-safe landscaping
Home Landscaping for Fire from UC ANR
http://ucanr.org/freepubs/docs/8228.pdf
Landscaping Tips to Help Defend Your Home from Wildfire from UC ANR Master Gardeners Program
http://anrcatalog.ucdavis.edu/Items/8322.aspx
UCCE Statewide Master Gardener Program
http://camastergardeners.ucdavis.edu/
SAFE Landscapes from Los Angeles County Cooperative Extension
http://celosangeles.ucdavis.edu/Natural_Resources/Wildland_Fire.htm
Wildfire Zone Interactive Website from San Diego County Cooperative Extension
http://www.wildfirezone.org
University of Nevada Cooperative Extension
http://www.livingwithfire.info/tahoe/
En Espanol
Prepare su hogar
http://firecenter.berkeley.edu/homeassessment/spanish/home_assess_intro_sp.html
Propietarios de vivienda: que hacer despues de un incendio
http://firecenter.berkeley.edu/toolkit/homeowners_afterfire_spanish.html
For information on fire-safe structures
Fire Information Engine Toolkit
http://firecenter.berkeley.edu/toolkit
Homeowners Wildfire Mitigation Guide
http://groups.ucanr.org/HWMG/
For general fire information
Center for Fire Research and Outreach
http://firecenter.berkeley.edu
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