A rapid technique to quantify bark fuel hazard with smartphones

Abstract

In eucalypt forests, tree bark can be a major contributor to the potential spread and behaviour of a wildfire and suppression difficulty. In particular, very fine fibres of bark found on eucalypt stringybark provides highly flammable material that can produce large quantities of embers and short distance spotting. In contrast, long strips or ribbons of bark can produce substantial spotting at distances greater than 2km. Due to these impacts on fire behaviour, land managers emphasise the importance of assessing bark within their hazard evaluation protocols and may target specific mitigation approaches via prescribed burning to reduce the hazard. Such hazard assessments not only inform prescribed burning priorities but also play an important role as input variables into fire spread and behaviour models. Bark type, thickness, size and shape are assessed in combination with the attachment characteristics to determine the potential hazard posed by the trees within the forest. Having accurate, reliable and quantitative information is necessary for input into these models. To date, assessment of bark hazard relies on qualitative and subjective visual assessments. In this paper we present an alternative to visual assessments by using image analysis and photogrammetry (or remote sensing) techniques applied to photographs taken using smartphones.