Estimating canopy fuel load with hemispherical photographs: A rapid method for opportunistic fuel documentation with smartphones

Abstract

Canopy fuel load (CFL) affects wildfire intensity and is a critical input for fire behaviour models; however, measuring CFL in the field is time-consuming and costly. Until recently, hemispherical photographs have been unable to adequately describe canopy metrics in non-diffuse light conditions. Recent developments allow calculation of canopy openness (CO) and leaf area index (LAI) using hemispherical photographs taken in sunny conditions. We describe an inexpensive and effective method for estimating CFL in the field opportunistically using CO and LAI values derived from hemispherical photographs taken in variable lighting conditions with a smartphone and fisheye lens attachment. Implications of this work include: new data for modelling effects of forest structure on fire behaviour; inexpensive assessment and monitoring of forest structure changes over time and in relation to management actions; and decision support for fuel treatment planning and prescribed burning operations.