Introduction
The U.S. continues to expand rapidly throughout the country as post-war baby boomers retire to their dream homes and other generations escape the stresses of urban living by relocating to smaller cities and rural communities. Studies show that this population redistribution seeks mild climates, varied topography and access to rivers and lakes or those more remote areas near or within wildland areas. The same studies indicate that the relocation of retirement age baby boomers will reach its peak near 2010 and continue until approximately 2015.
Often new residents to these wildland areas don’t fully comprehend how the natural disturbance of wildland fire is so important to the health and diversity of these landscapes. Virtually all of the country’s wildland areas have adapted to some level of wildland fire, either ground fire (which burns organic materials below the surface like peat and coal), surface fire (which burns low debris above the ground like grasses and shrubs), or crown fire (which burns through the tops of trees and large shrubs).
Wildland fire is nature’s method of recycling the limited nutrients available in dry ecosystems, stimulating growth, and maintaining diversity. Other natural events, including ice storms, hurricanes and high-wind events, often facilitate wildland fire frequency and intensity by putting more fuels on the ground for the next fire season. This can significantly increase a community’s wildland fire exposure, as many areas of the country experience seasonal fire weather conditions several times during a single calendar year.
Today the health and diversity of many of our wildland areas have already been compromised because of the lack of cyclic natural fire. These “natural” areas near our communities, that we hesitate to disturb, become stagnated areas of overgrown fuels desperate for renewal and providing potential for overdue wildland fires.
When these wildland fire cycles are interrupted or eliminated, our forests, grasslands and even preserved natural areas accumulate excessive fuels and become uninhabitable to a variety of wildlife species. This contributes to reduced biodiversity, declines in wildlife numbers, and encourages the increase of insects and diseases required to facilitate ecosystem renewal.
When people locate residences and communities near wildland areas, they increase their risk to wildfire loss by constructing combustible houses and landscaping near them with volatile plants. Combined with the naturally flammable wildland vegetation and unpreventable wildfire ignitions, these conditions perpetuate America’s modern day wildfire disasters, where firebrands and flames from weather-driven wildfires ignite numerous homes despite our best firefighting preparation and efforts.
Without a change in the patterns of flammable construction and landscaping, the probabilities of wildfire disaster in our communities increase seasonally. The positive news in this developing situation is that today’s wildfire disasters are a solvable problem. Recent wildland fire research has provided wildfire experts and residents of these wildland/urban (WU) areas with construction and landscaping mitigation alternatives that are visually attractive and cost effective.
Many communities across America are successfully organizing, developing, and implementing these strategies through individual local efforts and programs like Firewise, Fire Safe, FireFree and others. As they have discovered, responsibility for effective planning, application and maintenance of these wildfire mitigation programs requires a total community effort and in return provides tremendous fire protection payoffs in advance of severe wildfires.
The goal of Blueprint for Safety is not to stop wildland fires – nor is it to prevent people from living in areas affected by wildland fire. Blueprint’s goal is to foster construction and retrofit of compatible wildland residences and communities resilient to wildfire damages.
The Conditions needed for a Wildfire
1. Fuels – The basic fuels in WU fires are vegetation, structures and other combustibles.
- Light fuels (grasses, bushes, etc.) burn faster but with less intensity than heavy fuels like trees.
- Ladder fuels are those fuels (ex., lower tree branches) that can transfer a surface fire to the tops of trees.
- Structures – This includes combustible buildings. Their location and density affect their ability to transfer fire from one to another.
- Other Combustibles – This includes all other flammable materials and debris adjacent to homes that will burn, i.e., stacks of firewood, lumber, vehicles, etc.
2. Weather – Conditions of high temperatures, low humidity, high winds and other specific climatic conditions (drought, etc.) that increase the rate of WU fire spread and its difficulty to control.
3. Topography – The contours of the land affect the spread and behavior of WU fire.
- Slope – As it preheats up-slope fuels, fire burns uphill faster than on level ground.
- Aspect – The direction in which a slope faces. Fuels on southern facing slopes
generally dry faster and as a result burn faster.
Buildings Exposed to Wildfires are Ignited by
1. Radiant Heat – High heat transmitted through the air from large flames can fracture windows without actual flame contact, allowing firebrands to enter a building and cause internal ignitions that are difficult to suppress and often result in structure incineration.
2. Convective Heat – High heat, off the tips of flames, contacts and ignites flammable structural materials
3. Firebrands – Burning debris and embers carried and deposited by winds over a mile away from the fire, ignite flammable roofs and surfaces, vegetation near buildings and enter structural openings causing internal ignitions.
