Fuel mastication (mulching) is a widely promoted fuel treatment to mitigate the threat of wildfires in the wildland-urban interface. Mulched fuels produce a different type of fuelbed that may exhibit different fire behaviour when compared to untreated forests. Many have raised the question of whether mulched fuels create more firebrands than untreated forests. Firebrands are burning pieces of wood that are projected beyond the perimeter of a wildfire. When they land they can ignite the fuelbed and create a spot fire. Spot fires advance the spread of forest fires and are a characteristic of extreme fire behaviour, but they are not well studied. To better understand spot fires, we need a better understanding of how firebrands are produced. To research firebrand production, we need to first assess the different methods for collecting firebrands. This study evaluated four methods on a small experimental fire: (1) pans with water, (2) pans with water and with a screen, (3) a tarp and (4) a cloth sheet coated with fire retardant. Our results showed that of the two pan methods, the pan with screen collected fewer firebrands,
but the firebrands were heavier than the firebrands collected in the pans without the screen. The tarp almost entirely melted and was an unsuccessful method. The sheet coated with fire retardant was successful in creating a record of firebrand deposition through the presence of recognizable burn marks. Results from the sheets showed that most burning firebrands are relatively small and that as firebrand size increases the frequency of firebrand deposition decreases. An analysis of the sheets and the video footage revealed that an average of 4% of firebrands collected are burning at the time of collection.The advantages of the pan methods were that they captured the firebrands and kept them intact for analysis. The disadvantages were that they required more time to set-up and they did not allow us to distinguish between burning (or glowing) firebrands and extinguished firebrands. The advantages of the sheets were that they only collected data for burning (or glowing) firebrands
and they were easy to set up. The disadvantage was that the sheets did not preserve the firebrand itself for analysis.
We recommend that future research continue to explore firebrand collection methods as an important step toward understanding firebrand production. Firebrand production is an important area of research to expand the current knowledge base on spot fires. This in turn is beneficial to help create more accurate models of forest fire behaviour, which can help wildfire managers in their decision-making. An understanding of firebrand production in mulched fuels can help evaluate the effectiveness of mulch as a forest fuel treatment.