Just Accepted

This article has been peer reviewed and accepted for publication. It is in production and has not been edited, so may differ from the final published form.

Understanding variability in heat yields of wet sclerophyll forest fuels

Wey Yao Wong , Jane Cawson , Thomas Duff , Patrick Lane, Gary Sheridan

Abstract

Background; Fireline intensity is important for understanding fire behaviour. Heat yield – the amount of energy released by fuels, calculated by subtracting energy lost by vaporising moisture from a fuel’s calorific value – is considered the least variable component of fireline intensity. Recent work suggests it may be more variable than assumed, though how it varies between fuels and seasons remains unclear. Aims; This study aims to determine how heat yields vary between fuels and seasons in terms of calorific values, hydrogen content, and fuel moisture. Methods; We sampled common wet sclerophyll forest fuels over a year, measuring their moisture content. We determined their calorific value with bomb calorimetry, and hydrogen content with elemental analysis. Key results; Fuel heat yields varied substantially between species and seasons, with some species having large seasonal variations. The heat yields of live fuels were significantly lower than dead fuels. Conclusions; Heat yields are highly variable between fuels. Accounting for species composition and seasonal variation may be important for accurately estimating heat yield at the forest-stand scale. Implications; Heat yields are more variable than previously assumed and have been overestimated in some models. This could have implications for fireline intensity.

WF24227  Accepted 12 July 2025

© CSIRO 2025