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Unit 2: Fuels Classification

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Shrub Group

Fuel Model Description Common Types/Species Fire Behavior
4. Chapparral (6 feet) Fire intensity and fast spreading fire involve the foliage and live and dead fine woody material in the crowns of the nearly continuous secondary overstory. Dead woody material in the stand significantly contributes to fire intensity. There may also be a deep litter layer that confounds suppression efforts. Stands of mature shrubs, 6 or more feet tall, such as California mixed chaparral, the high pocosins along the east coast, the pine barren of New Jersey or the closed jack pine stands of the north central states are typical candidates. Red slash sites with 40 tons per acre or more of less than 3 inch material can also be considered. Very high to extreme rates of spread can be experienced in this model. Very high intensities make control efforts difficult.
5. Brush (2 feet) Fire is generally carried in the surface fuels that are made up of litter cast by the shrubs and the grasses or forbs in the understory. Shrubs are generally not tall but have nearly total coverage of the area. Best fits the generally non-flammable shrubs such as laurel, salal, vine maple, alder or mountain mahogany. Young, green stands of chaparrel, manzinita, and chamise qualify until dead-wood is generated. Fires are generally of low intensity as surface fuel loads are light, shrubs are young with little dead, and the foliage ocntains little volatile materials.
6. Intermediate Brush Hardwood Slash Brush is taller than #5, but less height and fuel than #4. Foliage is generally flammable although moderate to strong winds may be required to carry fire in the crowns. A broad range of shrub conditions are covered, such as intermediate stands of chamise, chaparrel, oak brush low pocosin, and palmetto-gallberry. Pinyon-juniper shrublands may be present with winds of 20 mph or greater. Fresh but cured hardwood slash can be represented. Fire carries through the shrub layer with moderate winds, but drops to the ground at low windspeeds or openings in the stand.
7. Intermediate Brush Hardwood Slash Fires burn through the surface and shrub strata with equal ease, and can occur at higher dead fuel moisture contents because of flammable nature of live foliage and other live materials. Stands are generally between 2 and 6 feet high. Best fits the southern rough communities of the palmetto-gallberry understory/pine overstory association of the southeast coastal plains. Can be used for low pocosins when moisture content is high in the foliage. Rate of spread and fire intensity are both moderately high.
Copyright 2008, by the Contributing Authors. Cite/attribute Resource . admin. (2005, October 05). Unit 2: Fuels Classification. Retrieved January 07, 2011, from Free Online Course Materials — USU OpenCourseWare Web site: This work is licensed under a Creative Commons License Creative Commons License