Hazardous Fuel Reduction

Fuel management modifies the hazard posed by vegetation and structures by:

• reducing the available fuel (dead and living) in broad areas using prescribed fire or other method
• creating defensible space by converting the vegetation to a less-flammable type and distribution that is less hazardous
• by modifying structural features

Despite the availability of programs and options for reducing hazards, there are many barriers to fire mitigation.

Fuel reduction methods

A Wildland Urban Interface Home
That Needs to Reduce Fire Risks

Fuel reduction techniques are used to decrease hazardous fuels (i.e., flammable vegetation). Fuel management is especially critical in forest ecosystems located adjacent to residential areas because of the increased risks to people and property, enhanced resource values, and the increased difficulty of fire control and suppression (Kalabokidis and Omi 1998). Fuel modifications may be broadcast across large areas, applied to small selected lots, or designed as strips of various widths to impede fire spread into a developed area. Mechanical, chemical and biological methods are used to reduce hazardous fuel loads. Some examples of common fuel reduction methods follow:

• Prescribed burning is the careful application of fire to achieve land management goals. Fire is a natural component of most southern ecosystems that encourages the growth of some native plants and enhances wildlife habitat in addition to reducing accumulated fuels. Prescribed fire can usually be completed at comparatively low-cost. Disadvantages to using prescribed fire include smoke management and public health issues, limitations on the number of acres that can feasibly be burned each year, the necessity for repeat treatments as vegetation grows back, and the risk of fire escapes. Smoke problems from a prescribed burnin the wildland urban interface are minimized by burning during favorable, daytime, smoke dispersal conditions.
• Herbicides have longer lasting effects on the vegetation than other methods, and they may be the only treatment for invasive exotic species. Herbicides do not modify the soil structure, nor do they enhance the regeneration of most fire dependent organisms unless chemical treatments are combined with prescribed burning. Herbicides do not reduce dead biomass accumulations; in fact, they temporarily increase dead fuels and the potential fire danger for one to three years. Herbicides have comparatively moderate costs and generally low public acceptance.
• Mechanical fuel treatments such as mowing, disking, roller chopping, and hand removal are generally risk free, have a high level of public acceptance, and are the only methods that modify or disturb soil, if that is needed. Disadvantages to using mechanical treatments include the necessity of repeat treatments, moderate to high costs, limitations on wet sites and steep slopes, follow-up burning is often required, and personal safety concerns associated with the use of hand tools such as machetes and chainsaws.
• Using livestock to maintain fuels at an acceptable level is an uncommon, but effective method. Livestock grazing offers a semi-natural alternative that is usually lower cost and safer than other methods. Pastures that have recently been converted to pine plantations are often still dominated by grasses and grazing cattle reduce competition and fuel load. Disadvantages to using livestock include the need for fencing and water supply for the animals, local grazing restrictions, and re-sprouting vegetation.

Defensible space

A Wildland Urban Interface Home
That Needs to Reduce Fire Risks

Arkansas Firewise Home of the Month
(February 2004)

Defensible space is the area of modified vegetation between wildland fuels and structures that can reduce the intensity of fires close to structures, provide firefighters the chance to stop a wildfire quickly and efficiently, and reduce a structure fire when firefighting personnel and equipment are not immediately available to help (Bailey 1991; Randall 2003). Homeowners need to take proactive, preventative actions to reduce the wildfire risk to their property by modifying structures and creating a defensible space. Materials for roofing, siding, decks, and vents, plant selection, landscape design, and maintenance are the most critical elements for a fire-safe home (Hagen 1993). Defensible space can be a 30-foot clearing with tree islands or a greenbelt surrounding a planned community. A study in Florida showed that structures with less than 10 feet of brush clearance were 60% more likely to burn during a wildfire than homes with at least 30 feet of cleared brush (Abt and others 1987). Homes with non-flammable roof coverings (asphalt shingles, metal, tile) that are surrounded by 30 to 60 feet of modified vegetation are over 85% more likely to survive a wildfire than homes with flammable roofs and no vegetative clearance (Foote and others 1991). Defensible space can include firewise plants and native species that are low in flammability. Firewise plantshave a high moisture content in the leaves and branches, broad and thick leaves, open and loose branching patterns, deciduousness, low amounts of dead materials, and low amounts of resin. Some less flammable plants are dogwood, viburnum, redbud, sycamore, magnolia, oaks, red maple, wild azalea, sweetgum, winged elm, black cherry, persimmon, wild plum, and ferns. Fire-prone plants to avoid near structures are junipers, young pine trees, cedars, palmetto, wax myrtle, rhododedendron, mountain laurel, tall ornamental grasses and yaupon holly (U.S. Department of Agriculture, Forest Service 2003). Landscaping tips for mitigating fire hazard and creating defensible space include:

• Space plants carefully - use shrub islands or patches of perennials rather than continuous beds or plantings.
• Prune plants regularly - thin trees so branches do not touch each other.
• Remove all ladder fuels- trim lower branches up to 10 feet on tall trees, remove vines from trees and keep shrubbery away from pine trees so a fire in surface fuels cannot climb up these ladder fuels to the treetops.
• Remove dead leaves and other litter from around trees, shrubs and vines, and from a 3-5 foot strip next to the structure.
• Provide the landscape with sufficient moisture when fires are imminent

Fire resistant construction tips

Cedar Shake Roofs Replaced with
Non-Flammable, Class-A Roofing

Structural modifications to improve fire resistance include:

• metal, asphalt shingle, or tile roof
• balconies and decks constructed of materials approved for 1-hour fire resistance in accordance with the American Society of Testing Materials Standard E 119
• attic vents, soffit vents, foundation openings and other such openings covered with 1/8" mesh noncombustible corrosion-resistant metal screen
• street address clearly posted on the main street
• dual or triple pane thermal or tempered glass windows and glass doors, or fireproof shutters for windows
• sprinkler systems installed on roof or around eaves.