An adapted bench-scale Mass Loss Calorimeter (MLC) device for evaluating forest fuel flammability and combustion properties is proposed. This fire test apparatus consists of an MLC fitted with a chimney containing a thermopile. After the thermopile output has been calibrated by use of a methane burner, these data are used to quantify heat release, as an alternative to the classical measurement of oxygen consumption due to combustion. The results showed good repeatability and reasonable approximation to HRR values obtained with a cone calorimeter, and also demonstrated that each variable analyzed was significantly affected by the species considered.

Fuel management techniques are commonly used in shrublands to reduce wildfire risk. However, more information about the ecological effects of these treatments is needed by managers and ecologists. In an effort to address this need, we performed a replicated (4 replicates per treatment) 48-ha experiment in northern California chaparral dominated by Adenostoma fasciculatum to determine the effects of two fuel reduction types (prescribed fire and mastication) and three different seasons of treatment (fall, winter, and spring) on shrub cover, height, and seedling density. Exclosures (2.5 m 2 each) were also used to assess herbivory effects. By the third posttreatment year, prescribed fire treatments had higher shrub cover (71 ± 2%) than mastication (43 ± 4%). There was no treatment effect on shrub height, species richness, or composition. Seedling density was initially higher in prescribed fire treatments (31 ± 4 seedlings m -2 ) than mastication (3 ± 0 seedlings m -2 ); however, prescribed fire treatments experienced substantial mortality, especially spring burning, resulting in lower densities 3 years after treatments (18 ± 0 seedlings m -2 after fall and winter fire compared to 2 ± 0 seedlings m -2 after spring fire). A. fasciculatum remained the dominant shrub species after the treatments, and Ceanothus cuneatus recruitment was higher in fall burning. Deer herbivory only affected shrub height, especially in masticated units, resulting in heights of 55 ± 2 cm in unexclosed areas compared to 66 ± 4 cm inside exclosures by the third post-treatment year. Overall, our findings suggest that fuel treatments play an important role in shrubland community dynamics, at least in the short-term, with implications for re-treatment frequency, community structure, and wildlife habitat.

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Fuel bulk density and fuel moisture content effects on fire rate of spread were assessed in shrub fuels, comparing experimental data observed in outdoor wind tunnel burns and predictions from the physically-based model FIRETEC. Statistical models for the combined effects of bulk density and fuel moisture content were fitted to both the experimental and the simulated rate of spread values using non-linear regression techniques. Results confirmed a significant decreasing effect of bulk density on rate of spread in a power law in both laboratory burns and simulations. However, experimental data showed a lesser effect than simulations, suggesting a difference in the effective drag. Fuel moisture content effect was highly consistent, showing a similar exponential relationship with rate of spread in laboratory and in simulations. FIRETEC simulations showed similar orders of magnitude with predictions of two field-based empirical models, finding a significant correlation