How fire propagates from the dead surface fuel to the first branch in ornamental vegetation of WUI
Comment de feu se propage de la litière à la première branche dans la végétation ornementale des interfaces habitat-forêt
Ganteaume, A. ; Bertin, A. ; Audouard, M. ; Guerra, F. ; Lopez, J.M. ; Morge, D. ; Travaglini, C.
Type de document
Communication scientifique avec actes
Affiliation de l'auteur
IRSTEA AIX EN PROVENCE UR RECOVER FRA ; IRSTEA AIX EN PROVENCE UR RECOVER FRA ; IRSTEA AIX EN PROVENCE UR RECOVER FRA ; IRSTEA AIX EN PROVENCE UR RECOVER FRA ; IRSTEA AIX EN PROVENCE UR RECOVER FRA ; IRSTEA AIX EN PROVENCE UR RECOVER FRA ; IRSTEA AIX EN PROVENCE UR RECOVER FRA
Résumé / Abstract
In WUIs, the ornamental vegetation can be an efficient vector of fire propagation towards the housings. Understanding how the fire propagates from dead surface fuels to the plant would be a further step toward the assessment of the whole plant flammability and would help to improve fire prevention in WUI. The fire propagation from the litter to the first branch of a plant was assessed in laboratory for several ornamental species. These species were characterized by different parameters, such as leaf moisture content, leaf and litter physical parameters, number of leaves, first branch height and angle, used to explain the fire behaviour. Burning experiments were carried out using a fire bench, the flammability variables that characterized the ignitability, sustainability, combustibility and consumability were recorded. Two modalities of vegetation management (litter removal from under the plant vs no removal) were tested to assess their impact on fire propagation. For both modalities, the fire propagation from the litter to the branch significantly varied according to species. Regardless of species, when the litter was not removed, once the fire had propagated to the branch, the flames propagated horizontally till the total branch combustion. In contrast, removing the litter entailed a decrease in flammability parameters and no/incomplete horizontal flame propagation along the branch was recorded when the branch ignition had succeeded, the energy necessary to the flame propagation being too low. The modelling of vertical and horizontal ignition frequency, time-to-ignition, flaming duration, rate of branch combustion and percentage of burned branch allowed the identification and the impact of the most significant parameters (litter combustion, number of leaves, initial branch weight and total intensity among the most significant). Removing the litter from under the ornamental vegetation and choosing the species the least fit for fire propagation will help to mitigate the fire risk in WUI.
5th International Fire Behaviour and Fuels Conference, 11/04/2016 - 15/04/2016, Melbourne, AUS