Fuels: Canopy Fuel Characteristics

Canopy Cover-Percentage or Class
Stand (Canopy)-Height-ft or m
Canopy Base Height-ft or m
Canopy Bulk Density-kg/m3 or lb/ft3

Canopy Cover - Percentage or Class

The forest Canopy Cover (CC) describes the percent cover or cover class of the tree canopy in a stand. Specifically, CC describes the vertical projection of the tree canopy onto an imaginary horizontal surface representing the ground’s surface. Estimate of CC is used in adjustment of 20 feet winds to mid-flame, fuel moisture conditioning, and spotting distance models.

The scale illustrates representative CC percentages and ranges within each cover class.

Canopy Cover classification. This graphic depicts from above views of canopy cover and its effect on wind sheltering/reduction.

For surface fuels sheltered by a forest canopy on flat terrain. (Scott 2007)

Canopy Cover	Wind Sheltering
CC ≤ 5%	Unsheltered
5% < CC ≤ 10%	Partially Sheltered
10% < CC ≤ 15%	Partially Sheltered
15% < CC ≤ 30%	Fully Sheltered, Open
30% < CC ≤ 50%	Fully Sheltered, Open
CC > 50%	Fully Sheltered, Closed

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Stand (Canopy) Height-feet (ft) or meters (m)

The Stand or Canopy Height (SH) describes the average height of the top of the vegetated canopy. SH estimates are used in adjustment of 20 feet winds to mid-flame and in spotting distance models.

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Canopy Base Height-ft or m

The forest Canopy Base Height (CBH) describes the average height from the ground to a forest stand's canopy bottom. Specifically, it is the lowest height in a stand at which there is a sufficient amount of forest canopy fuel to propagate fire vertically into the canopy. Using this definition, ladder fuels such as lichen, dead branches, and small trees are incorporated. Estimate of CBH is used in the Crown Fire Initiation model.

Describing a Forest Canopy. This graphic highlights the way to think about the primary descriptors for crown fire prediction. Crown Bulk Density describes the crown fuel load and distribution. Stand Height describes height of canopy tops. Crown Base height represents the difficulty for surfaces fires to ignite the canopy. And Foliar Moisture content suggest how readily the canopy will burn.

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Canopy Bulk Density-kg/m3 or lb/ft3

The forest Canopy Bulk Density (CBD) describes the density of available canopy fuel in a stand. It is defined as the mass of available canopy fuel per canopy volume unit. Typical units are either kg/m3 (LANDFIRE default) or lb/ft3 (BehavePlus default). CBD estimates are used to determine the threshold spread rate, or surface wind speed, used to determine the likelihood of active crown fire.

Canopy Bulk Density is a difficult concept to apply to crown fire predictions. This image shows that CBD varies with height above ground.

The following graph, also displayed in the Crown Fire section under Crown Fire Initiation and Propagation, displays the threshold surface 20 feet wind speed or Crowning Index, necessary for producing active crown fire given a specific canopy bulk density.

Crowning Index. Based on Rothermel crown fire spread model, canopy bulk density can be related to the windspeed required to sustain crown fire.

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NWCG Latest Announcements

The Incident Position Standards and Next Generation Position Task Book are now available for Medical Unit Leader (MEDL)

Date: October 16, 2024
Contact: Incident Medical Subcommittee

NWCG is excited to announce that the NWCG Incident Position Standards for Medical Unit Leader, PMS 350-39 and NWCG Position Task Book for Medical Unit Leader (MEDL), PMS 311-39 are now available.

The Performance Support Package, which for MEDL includes the Incident Position Standards and Next Generation Position Task Book, were developed through the Incident Performance and Training Modernization (IPTM) effort. The Performance Support Package will support trainees, those qualified in the position, and evaluators.

References:

NWCG Medical Unit Leader Position Page

NWCG Incident Position Standards for Medical Unit Leader, PMS 350-39

NWCG Position Task Book for Medical Unit Leader (MEDL), PMS 311-39

The Wildland Fire Learning Portal is Now Available

Date: October 9, 2024
Contact: Wildland Fire Learning Portal

The Wildland Fire Learning Portal (WFLP) is back online following a migration to a new learning management system (LMS) application. The WFLP team is actively addressing any issues that may arise as a result of the update, and appreciates your patience as the team works to enhance your experience. NWCG will share information from the WFLP as it is available.

Should you have any issues with accessing or using the WFLP, please use the link below to submit a ticket through the Help Center.

References:

Wildland Fire Learning Portal

Wildland Fire Learning Portal Help Center

NWCG Equipment Technology Committee Releases New Equipment Bulletins

Date: September 27, 2024
Contact: Equipment Technology Committee

The Equipment Technology Committee (ETC) has released three new Equipment Bulletins:

ETC-EB-24-003 Diesel exhaust fluid (DEF) in fuel containers.
ETC-EB-24-004 Two-compartment fuel and oil container (Dolmar) unavailable in the United States (US) and reminders for upkeeping current inventories.
ETC-EB-24-005 Personal Protective Equipment (PPE): Inspection, Care, and Maintenance.

These bulletins remind field going personnel of important issues related to equipment for wildland firefighting efforts.