Assessing the impact of fuel moisture content and incident heat flux on fire behavior for Leylandii cypress in small-scale laboratory experiments

Laboratory experiments were conducted on fresh Leylandii cypress leaves and small branches to evaluate fire behavior sensitivity to fuel moisture content and incident heat flux. Cone calorimetry combined with Fourier transform infrared spectroscopy provided novel insights into ignition dynamics, heat release, and emissions of water vapor, CO, and CO 2 . Fire behavior exhibited either a single ignition (leading directly to flaming), typical of higher fuel moisture content and incident heat flux, or an initial global ignition followed by localized ignitions, typical of lower fuel moisture content and incident heat flux. Peak heat release rate per unit mass and effective heat of combustion decreased on average with increasing fuel moisture content. At high fuel moisture content, CO, and water vapor concentrations were elevated before the first ignition and remained high afterward. Water vapor showed small peaks during flaming phases.