Linking leaf chemical traits to flammability properties of cool temperate rainforest leaf litter

Context Cool temperate rainforests are important refuges for biodiversity. Changing climatic conditions and the increasing incursion of fire are threats to the persistence of cool temperate rainforests. Understanding plant flammability is critical for understanding the persistence of rainforest patches under shifting fire regimes. Aims To better understand the role of leaf chemistry in driving leaf litter flammability properties in cool temperate rainforests of eastern Australia. Methods We conducted flammability experiments on leaf litter material from 14 species using a mass-loss calorimeter. Chemical leaf traits were also measured for eight species. We examined how flammability varies between species and trait-flammability relationships. Key results Rainforest species showed varying flammability, some comparable to Eucalyptus campanulata, a common in adjacent fire-prone eucalypt forest and woodland. Leaf chemistry (lignin, soluble content, P, N, and ash content) strongly influenced flammability; leaves with less lignin and more soluble cell content (e.g. sugars) ignited faster, while carbon-rich leaves burned longer. Peak heat release rate was higher with greater P, N, and ash content. Conclusions Fire behaviour in cool temperate rainforests will differ based on the rainforest tree species composition of the stand, some species may burn more intensely (e.g. Doryphora sassafras) whilst others are less so (e.g. Ceratopetalum apetalum). Leaf chemistry is an important driver of interspecific variation in flammability. Implications Understanding species flammability and underlying drivers is critical for informed fire planning, fire behaviour prediction, and incident management. We examined interspecific variation in flammability using a mass-loss calorimeter, further tests are required to examine whether the leaf chemical traits continue to be important at the branch or whole-plant scale.