Pacific Southwest Research Station

Masticated Fuels

Background

Dense flammable vegetation and seasonally extreme fire weather present a daunting fuels management challenge in the foothill and mountain regions of California and southern Oregon. Much of this area historically burned in relatively frequent low to moderate severity fires, helping to thin the forest understory and reduce the potential for severe wildfires. Fire suppression, past management practices, and unusually severe wildfires have all contributed to the dense thickets of shrubs and small trees common in many areas today. Prescribed fire is one means of reducing wildfire hazard, but risks associated with the proximity to homes, air quality issues, and the lack of prescription burning opportunities limit its use. Treatment of shrub and small tree fuels with mechanical mastication is one alternative. When we started the project little was known about the effectiveness of mastication for altering fire behavior, and about the fire behavior and fire effects of burning masticated fuel beds.

In order to address some of the unknowns, researchers with the U.S. Forest Service Pacific Southwest Research Station, Humboldt State University, and Mississippi State University began looking at fire effects from burning masticated fuels. Early work resulted in a paper showing the potential for substantial soil heating when masticated fuels are burned (Busse et al. 2005). The research was later expanded with funding from the Joint Fire Science Program (JFSP) (2005 to 2008). With new funding from JFSP (2013 to 2015), we will revisit masticated sites from the first phase of research and additional sites with varying treatment history to evaluate surface and live fuel succession over time, and determine how decomposition of masticated residues influences potential fire behavior.

Publications

• Kreye J.K., Varner J.M., Knapp E.E. 2012. Moisture desorption in mechanically masticated fuels: effects of particle fracturing and fuelbed compaction. International Journal of Wildland Fire 21:894-904
• Knapp E.E., Varner J.M., Busse M.D., Skinner C.N., Shestak C.J. 2011. Behavior and effects of prescribed fire in masticated fuelbeds. International Journal of Wildland Fire 20: 932-945.
• Kreye, J.K., J.M. Varner, and E.E. Knapp. 2011 Effects of particle fracturing and moisture content on fire behavior in masticated fuelbeds burned in a laboratory. International Journal of Wildland Fire 20:308-317.
• Busse, M., C. Shestak, E. Knapp, G. Fiddler, and K. Hubbert. 2010. Soil physical properties regulate lethal heating during burning of woody fuels. Soil Science Society of America Journal 74:947-955.
• Kane, J., J.M. Varner, and E.E. Knapp, and R.F. Powers. 2010. Understory vegetation response to mechanical mastication and other fuels treatments in a ponderosa pine forest. Applied Vegetation Science 13:207-220.
• Kane, J., J.M. Varner, and E.E. Knapp. 2009. Novel fuelbed characteristics associated with mechanical mastication treatments in northern California and southwestern Oregon. International Journal of Wildland Fire 18:686-697.
• Knapp, E.E., M.D. Busse, J.M. Varner, and C.N. Skinner. 2008. Masticated fuelbeds: custom fuel models, fire behavior, and fire effects. Final report to the Joint Fire Science Program. Project 05-2-1-20. 17p.
• Busse, M., C. Shestak, E. Knapp, G. Fiddler, and K. Hubbert. 2006. Lethal soil heating during burning of masticated fuels: effects of soil moisture and texture. Proceedings of the Third International Fire Ecology and Management Congress, Nov. 13-17, San Diego , CA.
• Kane, J., J.M. Varner, and E. Knapp. 2006. Initial Understory Vegetation Response to Mechanical Mastication Fuel Treatments: Balancing Biodiversity and Fire Hazard Reduction. Proceedings of the Third International Fire Ecology and Management Congress, Nov. 13-17, San Diego, CA.
• Kane, J. M., and J. M. Varner. 2006. Variability in loading of mechanically masticated fuel beds in northern California and southwestern Oregon. In Andrews, P.L., and Butler , B.W., comps., Fuel Management – How to Measure Success: Conference Proceedings, March 28-30, 2006 , Portland OR . U.S.D.A. Forest Service, Proceedings RMRS-P-41, pages 341-350.
• Knapp, E., M.Busse, J. Morgan Varner III, C. Skinner, and R. Powers. 2006. Behavior and short-term effects of fire in masticated fuel beds. Proceedings of the Third International Fire Ecology and Management Congress, Nov. 13-17, San Diego, CA.
• Matt D. Busse, Ken R. Hubbert, Gary O. Fiddler, Carol J. Shestak, and Robert F. Powers (2005). Lethal soil temperatures during burning of masticated forest residues. International Journal of Wildland Fire. 14:267-276.
• An overview of the project, written by the Joint Fire Science Program is located at: http://www.firescience.gov/projects/briefs/05-2-1-20_FSBrief70.pdf