Figure 3- Home with Defensible Space (14495370044) (cropped)

A defensible space, in the context of

fire control Fire control is the practice of reducing the heat output of a fire, reducing the area over which the fire exists, or suppressing or extinguishing the fire by depriving it of fuel, oxygen, or heat (see fire triangle). Fire prevention and control i ...

, is a natural and/or landscaped area around a structure that has been maintained and designed to reduce fire danger. The practice is sometimes called firescaping. "Defensible space" is also used in the context of

wildfire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identi ...

s, especially in the wildland-urban interface (WUI). This defensible space reduces the risk that fire will spread from one area to another, or to a structure, and provides firefighters access and a safer area from which to defend a threatened area. Firefighters sometimes do not attempt to protect structures without adequate defensible space, as it is less safe and less likely to succeed.

Criteria

*A first concept of defensible space for most fire agencies' primary goal of fuel reduction is a recommended or required defensible space around a structure to extend for at least in all directions. *A second concept of defensible space is "fuel reduction." This means plants are selectively thinned and pruned to reduce the combustible fuel mass of the remaining plants. The goal is to break up the more continuous and dense uninterrupted layer of vegetation. *A third concept of defensible space is "

fuel ladder A fuel ladder or ladder fuel is a firefighting term for live or dead vegetation that allows a fire to climb up from the landscape or forest floor into the tree canopy.

Landscape use

The term defensible space in landscape ("firescape") use refers to the zone surrounding a structure. Often the location is in the wildland–urban interface. This area need not be devoid of vegetation by using naturally fire resistive plants that are spaced, pruned and trimmed, and irrigated, to minimize the fuel mass available to ignite and also to hamper the spread of a fire. #The first is the "Defensible Space Zone," of a defensible space around a structure. It is where

vegetation Vegetation is an assemblage of plant species and the ground cover they provide. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characte ...

is kept to a minimum combustible mass. A guideline used in this zone can be "low, lean and green." Trees should be kept to a minimum of ten feet from other trees to reduce risk of fire spread between trees. Wood piles should be kept in zone 2. No branches should be touching or hanging over the roof of the house or within 10 feet of the structure to help keep the structure safe. Any dead vegetation or plants from zone 1 should be removed, and vegetation near windows should be pruned or removed. #The second distance of , is the "Reduced Fuel Zone" of a defensible space around a structure. In this area of the defensible space, fuels/vegetation are separated vertically and horizontally depending on the vegetation type. This is done by: thinning, pruning, and removal of selected vegetation; and removing lower limbs from trees closer to lower vegetation and the lateral separation of

tree canopies In biology, the canopy is the aboveground portion of a plant cropping or crop, formed by the collection of individual plant crowns. In forest ecology, canopy also refers to the upper layer or habitat zone, formed by mature tree crown ...

. Grass height should not exceed 4 inches. Trees should be 10 feet away from each other on a flat to mild slope but should be double that on a mild to moderate slope. Shrubs should be as far away as twice its height for flat to mid-slope but 4 times its height for mild to moderate slope. Leaves, twigs, needles, clones, bark, and small branches should be removed but can be left up to a depth of 3 inches. Vertical space from trees to ground should be 6 feet while the vertical distance from a tree to a shrub should be the height of the shrub times three. An important component is ongoing maintenance of the fire-resistant landscaping for reduced fuel loads and fire fighting access. Fire-resistive plants that are not maintained can

desiccate Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. ...

, die, or amass deadwood debris, and become fire assistive. Irrigation systems and pruning can help maintain a plant's fire resistance. Maintaining access roads and driveways clear of side and low-hanging vegetation can allow large fire equipment to reach properties and structures. Some agencies recommend clearing combustible vegetation at minimum horizontal 10 ft from roads and driveways a vertical of 13 ft 6 inches above them. Considering the plant material involved is important to not create unintended consequences to habitat integrity and unnecessary aesthetic issues. Street signs, and homes clearly identified with the numerical address, assist access also.

Unintended consequences

The unintended negative consequences of

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is dis ...

and native

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

loss can result from some unskillful defensible space applications. The disturbance of the soil surface, such as garden soil cultivation in and

firebreak A firebreak or double track (also called a fire line, fuel break, fireroad and firetrail in Australia) is a gap in vegetation or other combustible material that acts as a barrier to slow or stop the progress of a bushfire or wildfire. A firebre ...

s beyond native landscape zones areas, destroys the native plant cover and exposes open soil, accelerating invasive species of plants ("invasive exotics") spreading and replacing native

s. In suburban and wildland–urban interface areas, the vegetation clearance and brush removal ordinances of municipalities for defensible space can result in mistaken excessive clearcutting of native and non-invasive introduced shrubs and perennials that exposes the soil to more light and less competition for

invasive plant species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species adv ...

, and also to erosion and landslides. Negative aesthetic consequences to natural and landscaped areas can be minimized with integrated and balanced defensible space practices.USA (1999). Executive Order 13112 of February 3, 1999: Invasive Species. Federal Register 64(25), 6183-6186.

References

External links

CAL-FIRE: Homepage + Links
Official CA State Board of Forestry and Fire Protection website.
CA State Board of Forestry and Fire Protection: "General Guidelines for Creating Defensible Space"
Official Santa Barbara County Fire Department 'Wildfire' Website.
Santa Barbara County Fire Department: "Landscape Checklist"Santa Barbara County Fire Department: "Homeowner Checklist"
{{DEFAULTSORT:Defensible Space (Fire Control) Wildfire prevention Wildfire suppression Gardening aids Sustainable forest management Wildfires

Criteria

Unintended consequences

See also

References

External links