Increasingly, land managers have been conducting fuels treatments to alter canopy fuel characteristics, disrupt vertical fuel continuity, and reduce available fuels for combustion. These treatments are designed to moderate fireline intensity, reduce crown fire potential, and improve access for suppression resources (Agee and Skinner 2005; Moghaddas and Craggs 2007). Mechanical mastication (mulching, chipping) is a common fuels treatment applied to forests surrounding communities and along linear corridors such as hydro right-of-ways and pipelines.
Mastication shreds live and dead forest fuels (e.g., standing trees, understory vegetation, coarse woody debris) using a front-end or boom-mounted rotating drum with cutters, and generates a compact fuelbed of highly fractured, dead woody material (Hood and Wu 2006). The characteristics of this manufactured fuelbed and the corresponding influences on fire behaviour are unknown. A combination of thinning and mulching reduces aerial fuel loads and decreases the potential for crown fire, but this approach redistributes the aerial fuels onto the forest floor and increases surface fuel loads. This could affect the likelihood of a successful ignition as well as affect the resulting fire behaviour.
Limited information is available regarding the potential fire behaviour and ecological effects of mulch fuelbeds. One of the more comprehensive publications on the topic, Stephens et al. (2012) summarizes a broad range of studies conducted in the United States that looked at the influences of fuel management on potential fire behaviour, soils, vegetation, wildlife, and carbon sequestration. While some of the findings may be generally applied to certain forest types in Canada (particularly British Columbia), caution should be exercised in interpreting and applying the results to Canada’s boreal forests.