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Project ID: 13-1-05-8

Year: 2013

Date Started: 08/01/2013

Date Completed: 05/31/2017

Title: Surface Fuel Characteristics, Temporal Dynamics, and Fire Behavior of Masticated Mixed-Conifer Fuelbeds of the U.S. Southeast and Rocky Mountains

Project Proposal Abstract: Throughout the United States, large quantities of biomass from trees and shrubs have been chipped, chunked, shredded, or mowed to remove live fuel from the forest canopy and reallocate it to the forest floor as dead fuel. This thinning treatment, known as mastication, has become increasingly popular because land managers want alternatives to reduce canopy fuels and mitigate the risks from wildland fire where prescribed fire is problematic. One unknown in evaluating the costs and risks of mastication treatments is whether the risks of ignition, smoke, or chemical emissions actually increase over time in these decomposing materials. Little is known about the structural, physical, and chemical changes that mixed-conifer masticated materials undergo during decomposition, how moisture is retained throughout the summer and fall when potential for burning is high, how in situ moisture content fluctuates, or how aging affects fire behavior. This study examines mixed-conifer masticated fuelbeds of various ages at 10 sites in the southeast U.S. and Rocky Mountains. Our objectives are to: (1) describe the characteristics of aged masticated materials from diverse mixed-conifer forests; (2) determine the effect of fuel depth and time since treatment on masticated fuelbed moisture; (3) determine how the age of masticated materials affects the probability of ignition, smoldering, and mass loss; and (4) construct and validate custom fuel models that predict fire behavior in mixed-conifer masticated fuelbeds. Several features make the 10 study sites conducive to research on the characteristics and aging of masticated materials. They lie along a moisture and temperature gradient from very wet and hot conditions in the southeast to very dry and hot in the southwest and moist, cool conditions in the northern Rocky Mountains. They were treated with different mastication techniques enabling us to explore the effect of particle size on moisture and aging. They encompass several tree species and time-since-treatments from 1 to 12 years. Each is part of ongoing research on mastication treatments with established pre-treatment data and prescribed burn plans ready to implement. We will use a randomized complete block design to sample and characterize these diverse areas, which is the traditional sampling design tailored for areas where between-site variability is greater than within-site variability and sites are only sampled one time. We will examine the physical, structural, and chemical properties of the materials at each site to describe their fuel and fuelbed characteristics using field and laboratory techniques. We will examine how moisture is retained and varies seasonally by installing moisture probes within the fuelbeds in their natural setting. We will investigate how particle size, fuelbed depth, and the moisture affect ignition and smoldering potential in different ages of masticated materials with static burn-chamber burns. Using a combination of field characteristics and moisture data, we will design custom fuel models to fit field specifications then test and validate the models under controlled wind and humidity conditions in wind-tunnel burns. Masticated biomass creates novel fuelbeds for fire behavior, especially when it degrades physically and chemically over time. Research on how mixed-conifer masticated materials age, and if aged materials are more susceptible to ember ignitions or smoldering, is critical for managers to weigh the benefits and/or drawbacks of burning the materials immediately after treatment to reduce fire hazard or leaving materials on the ground until they decompose or are burned by unplanned wildfires. Our study will aid managers in assessing the risks of prescribed fire and/or responding to wildland fire in aged masticated materials and provide tools to predict fire behavior in them. A key aspect to this study is the link of fire behavior science to explicit recommendations for managers for treating these f

Principal Investigator: Robert E. Keane

Agency/Organization: Forest Service

Branch or Dept: RMRS-Fire, Fuel & Smoke Science Program

Other Project Collaborators




Branch or Dept

Agreements Contact

Cindy D. Gordon

Forest Service

RMRS-Rocky Mountain Research Station

Budget Contact

Edith M. Cates

Forest Service

RMRS-Rocky Mountain Research Station

Co-Principal Investigator

Theresa (Terrie) B. Jain

Forest Service

RMRS-Forestry Sciences Lab-Moscow

Co-Principal Investigator

James J. Reardon

Forest Service

RMRS-Fire Sciences Lab-Missoula

Co-Principal Investigator

Pamela G. Sikkink

Forest Service

RMRS-Forestry Sciences Lab-Moscow


Bret W. Butler

Forest Service

RMRS-Fire Sciences Lab-Missoula


Faith A. Heinsch

Forest Service

RMRS-Fire, Fuel & Smoke Science Program

Project Locations

Fire Science Exchange Network

Northern Rockies


Southern Rockies








Project Deliverables

Final Report view or print

("Results presented in JFSP Final Reports may not have been peer-reviewed and should be interpreted as tentative until published in a peer-reviewed source.")

  ID Type Title
view or print   1873 Government Publication Changes in Masticated Fuelbed Properties over Time in the Western U.S.
view or print go to website 1870 Government Publication Physical and chemical characteristics of surface fuels in masticated mixed-conifer stands of the U.S
view or print   1871 Government Publication Characterizing fire behavior from laboratory burns of multi-aged, mixed-conifer masticated fuels in
view or print   1872 Government Publication To masticate or not: useful tips for treating forest, woodland, and shrubland vegetation
view or print   3759 Journal Article International Journal Wildland Fire
view or print   3758 Journal Article Forest Ecology and Management
view or print   7888 Final Report Summary Final Report Summary

Supporting Documents

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