Mechanical mastication as a fuels treatment in southeastern forests

Mastication is an increasingly common fuels treatment that redistributes ‘‘ladder’’ fuels to the forest floor to reduce vertical fuel continuity, crown fire potential, and fireline intensity. Despite its widespread adoption, it remains unclear how mastication impacts fuels, fire behavior, or plant communities  across Southeastern forest ecosystems. We evaluated these effects by reviewing studies conducted across Southeastern pine forests. Mastication is typically applied to reduce fire hazard prior to reintroducing fire to long-unburned sites and to promote desired herbaceous groundcover where woody species have become dominant. Pretreatment fuel conditions varied across the different studies, ultimately leading to variation in post-treatment fuels. Only a few studies have examined fire behavior in masticated fuels and its potential effects. Field-scale burns conducted under mild conditions have resulted in variable fuel consumption and minimal overstory tree mortality. Substantial surface fuel loads in sites with prior stand damage, however, suggests that fire hazard may not be alleviated if sites burned under wildfire conditions. Modeled fire behavior indicates the effectiveness of treatments at reducing potential fire hazard, but verifying predictions under wildfire conditions has not been done. Initial herbaceous response has been positive in some sites, but rapid recovery of woody species indicates the importance of frequent burning to sufficiently restore plant communities and vegetation structure indicative of fire dependent pine forests in the Southeastern US.