Theses and Dissertations Collection

Managers masticate fuels to alter fire behavior, but how the resulting compact fuels burn is poorly understood. We burned 52 lab fuel beds and 75 field plots in 3 replicate, 30-yr old ponderosa pine (Pinus ponderosa) stands in fall after summer 2014 thinning. A mean 367-492 trees ha-1 remained after 30-72% of trees were masticated. Depth (8.1-13.7 cm) and loading (4.5 - 14.4 kg m-2, 45-60% were 0.6 - 2.5 cm). Pine needles facilitated ignition with flame lengths usually <1 m, rate of spread 0.3-3.5m min-1, and smoldering duration varied in the field, <1 hour in the lab regardless of 10-hr fuel moisture. Flame lengths and rates of spread were low and variable in masticated fuels, considerably less than the untreated controls. Two mastication treatments (coarse and fine) did not have statistically different fire behavior. Predictive equations based on lab experiments over-estimated flame length and consumption in prescribed burn experiments.