Appendix H - Glossary of Terms

El Dorado County Community Wildfire Protection Plan (CWPP)

Activity Fuels: Fuels resulting from, or altered by, forestry practices such as timber harvest or thinning, as opposed to naturally created fuels.

Aerial Fuels: Standing and supported live and dead combustibles not in direct contact with the ground and consisting mainly of foliage, twigs, branches, stems, cones, bark, and vines.

Aspect: Cardinal direction toward which a slope faces.

Atmospheric Stability: The degree to which vertical motion in the atmosphere is enhanced or suppressed. Vertical motion and pollution dispersion are enhanced in an unstable atmosphere. Thunderstorms and active fire conditions are common in unstable atmospheric conditions.

Available fuels: That portion of the total fuel that would actually burn under various environmental conditions.

Burning Index (BI): An estimate of the potential difficulty of fire containment as it relates to the flame length at the head of the fire. A relative number related to the contribution that fire behavior makes to the amount or effort needed to contain a fire in a specified fuel type. Doubling the burning index indicates that twice the effort will be required to contain a fire in that fuel type as was previously required, providing all other parameters are held constant.

Chain: Unit of measure in land survey, equal to 66 feet (80 chains equals 1 mile), commonly used to report fire perimeters and other fireline distances. This unit is popular in fire management because of its convenience in calculating acreage (e.g., 10 square chains equals one acre).

Community Defense Zone (CDZ): An area around or within a community where fuels need to be modified to reduce risk to the community from wildland fire. It also reduces the chance of a fire spreading into the wildland from the community and enhances actions owners take on their property. (Status of the Sierra Nevada; Sierra Nevada Ecosystem Project; Final Report to Congress, Wildland Resources Center Report Number 40)

Compactness: Spacing between fuel particles.

Convection Column: The rising column of gases, smoke, fly ash, particulates, and other debris produced by a fire. The column has a strong vertical component indicating that buoyant forces override the ambient surface wind.

Crown Fire: A fire that advances from top to top of trees or shrubs more or less independent of a surface fire. Crown fires are sometimes classed as running or dependent to distinguish the degree of independence from the surface fire.

Dead Fuels: Fuels with no living tissue in which moisture content is governed almost entirely by absorption or evaporation of atmospheric moisture (relative humidity and precipitation.)

Defensible Fuel Profile Zone (DFPZ): A strategically located block or strip of land on which living and deal fuels need to be or have been treated to create a reasonably safe and effective working environment for suppression and prescribed fire operations. Also see Fuel Break. (Status of the Sierra Nevada; Sierra Nevada Ecosystem Project; Final Report to Congress, Wildland Resources Center Report Number 40)

Defensible Space: The area within the perimeter of a parcel, development, neighborhood or community where basic wildland fire protection practices and measures are implemented, providing the key point of defense from an approaching wildfire or defense against encroaching wildfires or escaping structure fires. The perimeter as used in this regulation is the area encompassing the parcel or parcels proposed for construction and/or development, excluding the physical structure itself. The area is characterized by the establishment and maintenance of emergency vehicle access, emergency water reserves, street names and building identification, and fuel modification measures.

Direct Protection Area (DPA): That area which, by law or pursuant to the terms of (this) agreement, is provided wildland fire protection by the State or by the Bureau. DPAs may include a mixture of state, federal, and Local Responsibility Areas (LRA). (Cooperative Protection Agreement between USDI/ Bureau of Indian Affairs and the State of California.)

Diurnal: Daily, especially pertaining to cyclic actions which are completed within 24 hours, and which recur every 24 hours, such as temperature, relative humidity, and wind.

Energy Release Component (ERC): A number related to the available energy (BTU) per unit area (square foot) within the flaming front at the head of a fire. (The National Fire-Danger Rating System (NFDRS) - 1978, USDA Forest Service General Technical Report INT-39)

Fine Fuels: Fast drying deal fuels, generally characterized by a comparatively high surface area-to-volume ration, which are less than ¼ inch in diameter and have a timelag of one hour or less. These fuels (grass, leaves, needles, etc.) ignite readily and are consumed rapidly by fire when dry.

Fire Behavior: The manner in which a fire reacts to the influence of fuel, weather, and topography.

Fire Danger Rating Area: Geographical area within which climate, fuel, and topography are relatively homogenous, hence fire danger can be assumed to be uniform.

Fire Safe: A combination of steps taken to provide an adequate level of protection of a structure from a wildland fire. (Fire Safe - Inside and Out)

Fire Use: The combination of wildland fire use and prescribed fire application to meet resource objectives. (Federal Wildland and Prescribed Fire Management Policy)

Fireline: The part of a control line that is scraped or dug to mineral soil. (Fireline Handbook, NWCG handbook #3)

Fireline Intensity: The rate of heat release per unit length of the fire front. The most commonly used units in current fire literature are Btu/sec/ft. (The National Fire-Danger Rating System (NFDRS) - 1978, USDA Forest Service General Technical Report INT-39)

Fuel Break: A wide strip or block of land on which the native vegetation has been permanently modified so that fires burning into it can more readily be extinguished. It may or may not have Fireline constructed in it prior to fire occurrence. Also, see Defensible Fuel Profile Zone. (Fireline Handbook, NWCG handbook #3)

Fuel Reduction Zone (FRZ): An area in which continuous, high hazard fuels need to be fragmented and broken up. The purpose of treatment within these areas is to reduce fuels, break up crown closure, and reduce fuel ladders, resulting in lower fire intensities. (Status of the Sierra Nevada; Sierra Nevada Ecosystem Project; Final Report to Congress, Wildland Resources Center Report Number 40)

Fuel Type: An identifiable association of fuel elements of distinctive species, form, size, arrangement, or other characteristics that will cause a predictable rate of fire spread or difficulty of control under specified weather conditions. (Fireline Handbook, NWCG handbook #3)

Hazard: A fuel complex defined by kind, arrangement, volume, condition, and location that forms a special threat of ignition or of suppression difficulty. (Fireline Handbook, NWCG handbook #3)

Hazard Reduction: Any treatment of a hazard that reduces the threat of ignition and spread of fire. (Fireline Handbook, NWCG handbook #3)

Initial Attack: An aggressive suppression action consistent with firefighter and public safety and values to be protected. (Federal Wildland and Prescribed Fire Management Policy)

Initial Attack (2): The control efforts taken by resources which are the first to arrive at the incident. (Fireline Handbook, NWCG handbook #3)

Ignition Component: A rating of the probability that a firebrand will cause a fire requiring suppression action. (The National Fire-Danger Rating System (NFDRS) - 1978, USDA Forest Service General Technical Report INT-39)

Prescribed Burning: Controlled application of fire to wildland fuels in either their natural or modified state, under specified environmental conditions which allow the fire to be confined to a predetermined area and at the same time to produce the intensity of heat and rate of spread required to attain planned resource management objectives. (Fireline Handbook, NWCG handbook #3)

Prescribed Fire: any fire ignited by management actions to meet specific objectives. A written approved prescribed fire plan must exist, and NEPA requirements must be met, prior to ignition. (Federal Wildland and Prescribed Fire Management Policy)

Prescription: Measurable criteria, which define conditions under which a prescribed fire may be ignited, guide selection of appropriate management responses, and indicate other required actions. Prescription criteria may include safety, economic, public health, environmental, geographic, administrative, social, or legal considerations. (Federal Wildland and Prescribed Fire Management Policy)

Rate of Spread (ROS): The relative activity of a fire in extending its horizontal dimensions. It is expressed as rate of increase of the total perimeter or the fire, as rate of forward spread of the fire front, or as rate of increase of area. Usually expressed as chains or acres per hour. (Fireline Handbook, NWCG handbook #3)

Resistance to Control (RTC) : The relative difficulty of constructing and holding a control line as affected by resistance to line construction and by fire behavior. Also called "difficulty to control." (Fireline Handbook, NWCG handbook #3)

Risk: (1) The chance of a fire starting as determined by the presence of causative agents. (2) A causative agent. (3) Under the NFDRS system - a number related to the potential number of firebrands to which a given area will be exposed during the rating day. (Fireline Handbook, NWCG handbook #3)

Spread Component: A rating of the forward rate of spread of a head fire. (The National Fire-Danger Rating System (NFDRS) - 1978, USDA Forest Service General Technical Report INT-39)

SRA: State Responsibility Area for wildfire protection.

Wildland Fire: Any non-structure fire, other than prescribed fire, that occurs in the wildland. (Federal Wildland and Prescribed Fire Management Policy)

Wildland Fire Suppression: An appropriate management response to wildland fire that results in curtailment of fire spread and eliminates all identified threats from the particular fire. All wildland fire suppression activities provide for firefighter and public safety as the highest consideration, but minimizes loss of resource values, economic expenditures, and/or the use of critical firefighting resources. (Federal Wildland and Prescribed Fire Management Policy)