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In the context of [[fire control]], '''defensible space''' is the area around a structure that has been landscaped to reduce fire danger. "Defensible space" is also used in the context of [[wildfire]]s, especially in the [[wildland-urban interface]] (WUI). This space reduces the risk that fire will spread to the structure and also provides [[firefighter]]s a relatively safe area in which to work while protecting the structure. In areas prone to wildfires, firefighters will often not attempt to protect structures that do not have adequate defensible space, both for personal safety reasons and because such efforts are unlikely to be successful.
In the context of [[fire control]], '''Defensible Space''' is the natural and landscaped area around a structure that has been maintained and designed to reduce fire danger, sometimes called ''''Firescaping''''.<ref>http://www.sbcfire.com/fp/hrp/landscape%20checklist.pdf SBCFD-Firescaping. Retrieved 4/26/2010</ref> "Defensible space" is also used in the context of [[wildfire|wildfires]], especially in the [[Wildland-urban interface|wildland-urban interface]] (WUI).<ref>http://www.fire.ca.gov/communications/communications_firesafety_100feet.php CAL-FIRE intro Retrieved 4/26/2010</ref> This defensible space reduces the risk that fire will spread from the surroundings to the structure and provides [[firefighter|firefighters]] access and a safer area to defend it from. Firefighters sometimes do not attempt protecting structures without adequate defensible space, for personnel safety and their effort less likely to succeed.


Most agencies recommend that the defensible space around a structure extend for at least 100 feet (30 meters) in all directions. This area need not be devoid of vegetation, but plants should be selected, trimmed, spaced, and irrigated in such a way to minimize the fuel available to the fire and hamper the spread of the fire.


==Criteria==
The term Defensible Space refers to the {{convert|100|ft|m}} surrounding a property or structure. The first {{convert|30|ft|m}} around a structure, is where vegetation is to be kept to a minimum, also called the "Defensible Space Zone". A concept often used in this area is the "low, lean and green" concept, describing a basic and simple way of achieving and remembering how a property should be maintained in the first {{convert|30|ft|m}}. The distance of {{convert|30|to|100|ft|m}} in the Defensible Space zone is usually referred to as the "Reduced Fuel Zone". In this area of the defensible space, fuels/vegetation are to be separated vertically and horizontally depending on the vegetation type. Spacing guidelines can be met by thinning, pruning, limbing up trees from nearby vegetation, or removal of selected vegetation types and the separation of tree canopies. The Defensible Space zone can be required to be more than {{convert|100|ft|m}} if the given topography of the parcel would make the initial {{convert|100|ft|m}} not as effective.


*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 {{convert|100|ft|m}} in all directions.<ref>http://www.sbcfire.com/fp/hrp/defensible_space_requlation.pdf SBCFD-regulation. Retrieved 4/26/2010</ref>
⚫
One concept in Defensible Space is "Reducing the Fuel". This is where plants are selectively thinned and pruned to reduce the fuel volume of the remaining plants. The idea is to break up the more continuous and dense vegetation, instead of having an uninterrupted layer of vegetation.


⚫
*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.
⚫
Another concept is "Ladder Fuels". Like rungs on a ladder, vegetation can be present at varying heights. Grounds fuels, like grasses can transmit fire to shrubs and then into the trees limbs. When trees catch fire they start to produce and cast embers that can result in spot fires making it more difficult to control a wildland fire. Three times the height of the lower fuels is the typical separation for ladder fuels. For example, if a two foot high shrub just under a tree, a spacing of {{convert|6|ft|m}} between the lower limbs of the tree and the shrub is desirable. Remembering that fire burns uphill faster than on flat land, spacing may need to be greater if this vegetation is on a slope.


⚫
*A third concept of Defensible Space is "[[Fuel ladder|Fuel Ladder]]" management. Like rungs on a ladder, vegetation can be present at varying heights from groundcovers to trees. Grounds fuel 'rungs' such as dried grasses, can transmit fire to shrub rungs, which then transmit up tree branch rungs into the tree canopy. A burning tree produces embers that can blow to new areas spreading and so making it more difficult to control a wildland fire. One guideline is for a typical separation of three times the height of the lower fuel to the next fuel ladder. For example, a two foot high shrub under a tree would need a spacing of {{convert|6|ft|m}} to the lowest limbs of the tree. Since wildfires burn faster uphill than on flat land, fuel ladder spacing may need to be greater for slopes.<ref>http://www.sbcfire.com/fp/hrp.html SBCFD-intro. Retrieved 4/26/2010</ref>
In areas in a wildland-urban interface it is important to maintain fire-safe landscaping. Pick plants that are naturally fire resistive, then MAINTAIN them! Fire resistive plants that are not maintained can dry up or die and become part of the problem again. It is important to use a good irrigation system and keep all vegetation free of dead [[debris]]. This will help maintain the fire resistance of the plants and keep the landscaping looking nice.


Keep access roads, including driveways, clear of vegetation. Maintaining access allows large emergency equipment to reach residences. Clear combustible vegetation at least 10 feet from roads and driveways. If the fire department can't get to a house, they can't save the house. Also be aware of vertical clearance. Any trees or vegetation that hangs over roadways need to be cut to a height of at least 13 feet 6 inches. But make sure that is the typical height of responding apparatus to the area. Also make sure that the streets and homes are clearly marked with the address. If the fire department can't find the house, they can't save the house.


==Landscape use==
⚫
Provide Defensible Space, be fire-safe and fire-smart.


The term Defensible Space in landscape ('firescape') use refers to the {{convert|100|ft|m}} 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 {{convert|30|ft|m}} is the '''"Defensible Space Zone,"''' of a defensible space around a structure. It is where [[plants|vegetation] is kept to a minimum combustible mass. A guideline used in this zone can be ''"low, lean and green."''
#The second distance of {{convert|30|to|100|ft|m}}, 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 limbing up trees from lower vegetation and the lateral separation of [[canopy (forest)|tree canopies]]. types.<ref>http://www.sbcfire.com/fp/hrp/defensible_space_guidelines.pdf CAL-FIRE-guidelines. Retrieved 4/26/2010</ref>

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 [[Desiccation|desiccate]], die, or amass [[Coarse woody debris|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 feet from roads and driveways a vertical of 13 feet 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.<ref>http://www.sbcfire.com/fp/hrp/homeowners_checklist.pdf SBCFD Retrieved 4/26/2010]</ref><ref>http://www.sbcfire.com/fp/hrp/landscape%20checklist.pdf SBCFD-checklist. Retrieved 4/26/2010</ref>

⚫
:The slogan ''"Provide Defensible Space, be fire-safe and fire-smart"'' is used by agencies.


==Unintended consequences==

The unintended negative consequences of [[erosion]] and native [[habitat]] loss can result from some unskillful defensible space applications. The disturbance of the soil surface, such as garden [[Tillage|soil cultivation]] in and [[Firebreak|firebreaks]] beyond native landscape zones areas destroy the native plant cover and expose open soil, accelerating [[Invasive species|invasive species]] of plants ('invasive exotics') spreading and replacing native [[habitat|habitats]].<ref name=neutral>{{citation| last=Colautti| first=Robert I.; MacIsaac, Hugh J.| title=A neutral terminology to define 'invasive' species| journal= Diversity and Distributions|year=2004|url=http://planet.botany.uwc.ac.za/nisl/Invasives/Assignment1/ColauttiandMacIsaac.pdf|format=PDF| volume=10| pages=135–141| accessdate=2007-07-11| doi=10.1111/j.1366-9516.2004.00061.x}}</ref>

In suburban and [[Wildland-urban interface|wildland-urban interface]] areas the vegetation clearance and brush removal ordinances of municipalities for defensible space can result in mistaken excessive [[Clearcutting|clearcutting]] of native and [[Introduced species|non-invasive introduced]] shrubs and perennials that exposes the soil to more light and less competition for [[Invasive species|invasive plant species]], and also erosion and landslides. Negative aesthetic consequences to natural and landscape areas can be minimized with integrated and balanced defensible space practices.<ref>(September 21, 2006). [http://www.invasivespeciesinfo.gov/whatis.shtml National Invasive Species Information Center - What is an Invasive Species?]. ''United States Department of Agriculture: National Agriculture Library''. Retrieved on September 1, 2007.</ref><ref>USA (1999). Executive Order 13112 of February 3, 1999: Invasive Species. Federal Register 64(25), 6183-6186.</ref>


==References==
{{Reflist}}

==See also==
*[[Fire control]]
*[[Wildfire]]
*[[Fire ecology]]
*[[Wildfire suppression]]
*[[Firefighting]]
*[[Fuel ladder]]

==External links==
*[http://www.fire.ca.gov/communications/communications_firesafety_100feet.php CAL-FIRE: Homepage + Links] Official CA State Board of Forestry and Fire Protection website.
*[http://www.sbcfire.com/fp/hrp/defensible_space_guidelines.pdf CA State Board of Forestry and Fire Protection: "General Guidelines for Creating Defensible Space"]
*[http://www.sbcfire.com/fp/hrp.html SBCFD Homepage + Links: "Defending Your Home and Hazard Reduction"] Official Santa Barbara County Fire Department 'Wildfire' Website.
*[http://www.sbcfire.com/fp/hrp/landscape%20checklist.pdf Santa Barbara County Fire Department: "Landscape Checklist"]
*[http://www.sbcfire.com/fp/hrp/homeowners_checklist.pdf Santa Barbara County Fire Department: "Homeowner Checklist"]

{{portal|Gardening|Gymnaster savatieri1 flower.jpg}}
{{Fire fighting}}
{{Horticulture and Gardening}}
{{firefighting-stub}}
{{firefighting-stub}}

[[Category:Wildfires|Wildfires]]
[[Category:Natural hazards]]
[[Category:Wildland fire suppression]]
[[Category:Occupational safety and health]]
[[Category:Invasive plant species]]
[[Category:Horticulture and gardening]]
[[Category:Landscape]]

[[es:Categoría:Horticultura|Firescape]]

Revision as of 20:17, 26 April 2010


In the context of fire control, Defensible Space is the natural and landscaped area around a structure that has been maintained and designed to reduce fire danger, sometimes called 'Firescaping'.[1] "Defensible space" is also used in the context of wildfires, especially in the wildland-urban interface (WUI).[2] This defensible space reduces the risk that fire will spread from the surroundings to the structure and provides firefighters access and a safer area to defend it from. Firefighters sometimes do not attempt protecting structures without adequate defensible space, for personnel safety and their effort 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 100 feet (30 m) in all directions.[3]
  • 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" management. Like rungs on a ladder, vegetation can be present at varying heights from groundcovers to trees. Grounds fuel 'rungs' such as dried grasses, can transmit fire to shrub rungs, which then transmit up tree branch rungs into the tree canopy. A burning tree produces embers that can blow to new areas spreading and so making it more difficult to control a wildland fire. One guideline is for a typical separation of three times the height of the lower fuel to the next fuel ladder. For example, a two foot high shrub under a tree would need a spacing of 6 feet (1.8 m) to the lowest limbs of the tree. Since wildfires burn faster uphill than on flat land, fuel ladder spacing may need to be greater for slopes.[4]


Landscape use

The term Defensible Space in landscape ('firescape') use refers to the 100 feet (30 m) 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.

  1. The first 30 feet (9.1 m) is the "Defensible Space Zone," of a defensible space around a structure. It is where [[plants|vegetation] is kept to a minimum combustible mass. A guideline used in this zone can be "low, lean and green."
  2. The second distance of 30 to 100 feet (9.1 to 30.5 m), 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 limbing up trees from lower vegetation and the lateral separation of tree canopies. types.[5]

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, 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 feet from roads and driveways a vertical of 13 feet 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.[6][7]

The slogan "Provide Defensible Space, be fire-safe and fire-smart" is used by agencies.


Unintended consequences

The unintended negative consequences of erosion and native habitat loss can result from some unskillful defensible space applications. The disturbance of the soil surface, such as garden soil cultivation in and firebreaks beyond native landscape zones areas destroy the native plant cover and expose open soil, accelerating invasive species of plants ('invasive exotics') spreading and replacing native habitats.[8]

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, and also erosion and landslides. Negative aesthetic consequences to natural and landscape areas can be minimized with integrated and balanced defensible space practices.[9][10]


References

  1. ^ http://www.sbcfire.com/fp/hrp/landscape%20checklist.pdf SBCFD-Firescaping. Retrieved 4/26/2010
  2. ^ http://www.fire.ca.gov/communications/communications_firesafety_100feet.php CAL-FIRE intro Retrieved 4/26/2010
  3. ^ http://www.sbcfire.com/fp/hrp/defensible_space_requlation.pdf SBCFD-regulation. Retrieved 4/26/2010
  4. ^ http://www.sbcfire.com/fp/hrp.html SBCFD-intro. Retrieved 4/26/2010
  5. ^ http://www.sbcfire.com/fp/hrp/defensible_space_guidelines.pdf CAL-FIRE-guidelines. Retrieved 4/26/2010
  6. ^ http://www.sbcfire.com/fp/hrp/homeowners_checklist.pdf SBCFD Retrieved 4/26/2010]
  7. ^ http://www.sbcfire.com/fp/hrp/landscape%20checklist.pdf SBCFD-checklist. Retrieved 4/26/2010
  8. ^ Colautti, Robert I.; MacIsaac, Hugh J. (2004), "A neutral terminology to define 'invasive' species" (PDF), Diversity and Distributions, 10: 135–141, doi:10.1111/j.1366-9516.2004.00061.x, retrieved 2007-07-11{{citation}}: CS1 maint: multiple names: authors list (link)
  9. ^ (September 21, 2006). National Invasive Species Information Center - What is an Invasive Species?. United States Department of Agriculture: National Agriculture Library. Retrieved on September 1, 2007.
  10. ^ USA (1999). Executive Order 13112 of February 3, 1999: Invasive Species. Federal Register 64(25), 6183-6186.

See also

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