Calluna-heathlands are one of the most fire-prone vegetation types in NW Italy. Fire risk at the wildland urban interface is increasing. Moreover, frequent and large wildfires threat the Calluna-heathland, a Priority Habitat in Europe. Prescribed burning for fire hazard reduction could be a suitable tool to create fuel discontinuities in strategic areas so as to facilitate fire suppression.
... [Show full abstract] Nevertheless, its effectiveness has to be assessed and burn prescriptions need to be developed. The objective of the present work is to study the links between burning conditions, fire behaviour and fire effects on heathlands fuels of NW Italy. We carried out 25 experimental burns during the legal burning season in winter, both in unburnt (UB) heathlands stands of different ages (4-14 years) and recently burnt (BU) stands (1-3 yrs). The fuel complex load and structure was characterized before and after burning. Short-medium term post-treatment fuel dynamics were studied. The seasonal variation of fine fuels moisture was analysed. A linear regression model was developed to predict the dead fine fuel moisture as a function of weather variables. Fire behaviour was studied with a microplot scale approach. Rate of fire spread and fireline intensity were quantified for backfire (A), headfire in the acceleration phase (B), and headfire in the quasi steady state (C). Generalized linear models with Tukey's comparison were used to investigate differences in fuel load and structure vs. time since fire, and fire behaviour descriptors in BU vs. UB burns. Results evidenced that prescribed burning treatments significantly mitigated potential fire behaviour. In BU, observed fireline intensity in A, B, C behaviours was respectively the 26%, 38% and 20% of the UB values. Finally, operational windows (i.e. optimum moisture scenario; available days for burning) and technical recommendations (i.e. ignition techniques) to assist prescribed burning for fire hazard reduction in heath fuels of NW Italy were set out.
