Department of Environmental Protection

New Jersey Forest Fire Service

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Wildfire Definitions

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


Defensible Space: The area around the perimeter of wildland structures or developments which are key points of defense against encroaching wildland fires, or escaping structure fires. Defensible space provides the room for firefighters to safely conduct protection operations. Defensible space may include a firebreak as well as a fuelbreak within 3 Defensible Space Management Zones.

  • Zone 1: An area of maximum modification in which all flammable vegetation is removed (i.e. a firebreak).
  • Zone 2: A transitional area of fuel reduction between zones 1 & 3 where the continuity and arrangement of vegetation is modified (i.e. a fuel break).
  • Zone 3: An area of management designed to increase forest health and productivity by reducing the amount of overcrowding and related weakened and diseased trees, and thereby reducing the fuel loading.

Firebreak: A natural or constructed barrier used to stop or check fires that occur, or to provide a control line from which to work. A firebreak shall consist of non-flammable type materials such as gravel, sand, or paved roads, irrigated lawns, gardens and orchards, or ponds, lakes, and other watercourses that meet a specified width. This width is to be measured outward 1-1/2 times the height of fuels available to burn directly adjacent to the object. When used in conjunction with a fuelbreak, the size of the firebreak may be reduced.

Firelane: An existing cleared path that needs continuous maintenance to a minimum of 10 feet in width, which is used to gain access for emergency traffic.

Fireline: The part of a containment or control line that is scraped or dug to mineral soil. This may be used for a wildfire or prescribed burn.

Fire Hazard: A fuel complex, defined by volume, type condition, arrangement, and location that determines the degree of ease of ignition and of resistance to control.

Fire Risk: The chance of a fire starting, as determined by the presence and activity of causative agents. In New Jersey, the primary causative agent is humans.

Fuelbreak: A natural or manmade change in fuel characteristics that affect fire behavior so that fires burning into them can be more readily controlled (or managed). When used in conjunction with a firebreak, the following fuelbreak standards will be used;

  • In moderate fire hazard areas, a minimum fuelbreak of 30 feet is recommended as measured outward from the object.
  • In high fire hazard areas, a minimum fuelbreak of 75 feet is recommended as measured outward from the object.
  • In extreme fire hazard areas, a minimum fuelbreak of at least 100 feet (200 feet if it protects a community of 100+) is recommended as measured outward from the object.

The fire hazard classification is based on NJDEP Land Cover/Land Type GIS data. The recommended modification within the fuelbreak should consist of an average 50% reduction of canopy cover across the treatment and up to a 100% reduction in understory fuels. This fuel modification must be maintained over time.

Fuel Loading: The amount of fuel present expressed quantitatively in terms of weight per unit area. This may be available fuel (consumable fuel) or total fuel and is usually dry weight.

Fuel Modification: Manipulation or removal of fuels to reduce the likelihood of ignition and/or lessen potential damage and resistance to control (e.g., lopping, chipping, crushing, piling, and burning).

Fuelbreak System: A series of modified strips or blocks tied together to form continuous strategically located fuel breaks around land units.


Wildland/Urban Interface: The line, area, or zone where structures and other human development meet or intermingle with undeveloped wildland or vegetative fuels.

These definitions are compiled from recognized sources such as the “Glossary of Wildland Fire Terminology”, “Firewise©” publications, Pinelands Commission regulations, and other Forest Fire Service publications.

National Wildfire Coordinating Group Glossary of Wildland Fire Terminology