International Journal of Wildland Fire International Journal of Wildland Fire Society
Journal of the International Association of Wildland Fire

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Fire Behavior in Masticated Forest Fuels: Lab and Prescribed Fire Experiments

Zachary Lyon , Penelope Morgan , Camille Stevens-Rumann , Aaron Sparks , Rob Keefe , Alistair Smith

Abstract

Managers masticate fuels to reduce fire hazards, but the implications for fire behavior within the resulting compact fuelbeds is poorly understood. We burned 54 masticated fuelbeds in laboratory experiments one and two growing seasons after mastication and 75 masticated fuelbeds in prescribed fires experiments one growing season after treatment in three replicate Pinus ponderosa stands. Mastication treatments reduced density of trees >5cm by 30-72% resulting in total fuel depth of 6.9-13.7cm and surface woody fuel loading of 1.0-16.0kg m-2. Flame length and rate of spread were low and similar for coarse and fine mastication treatments and controls. Smoldering combustion lasted 6-22h in prescribed fire experiments where fuelbeds included duff and were well-mixed by machinery, compared to <2h in the lab where fuelbeds did not include duff and had varying fuel moisture. Fuel consumption in the prescribed fires was highly variable, ranging from 0-20 cm in depth and was less for 2-yr old than 1-yr old fuelbeds in laboratory burns. Coarse treatments took were more cost-effective than fine mastication. Lab experiments did not scale to prescribed burning conditions, so both lab and in-situ experiments are needed to understand and predict flame length, rate of spread and consumption.

WF17145  Accepted 11 February 2018

© CSIRO 2018