Data from: Burn or rot: leaf traits explain why flammability and decomposability are decoupled across species

In fire-prone ecosystems, two important alternative fates for leaves are
burning in a wildfire (when alive or as litter) or they get consumed (as
litter) by decomposers. The influence of leaf traits on litter
decomposition rate is reasonably well understood. In contrast, less is
known about the influence of leaf traits on leaf and litter flammability.
The aim of this study was twofold: (a) to determine which morphological
and chemical leaf traits drive flammability; and (b) to determine if
different (combinations of) morphological and chemical leaf traits drive
interspecific variation in decomposition and litter flammability and, in
turn, help us understand the relationship between decomposability and
flammability. To explore the relationships between leaf traits and
flammability of individual leaves, we used 32 evergreen perennial plant
species from eastern Australia in standardised experimental burns on three
types of leaf material (i.e. fresh, dried and senesced). Next, we compared
these trait-flammability relationships to trait-decomposability
relationships as obtained from a previous decomposition experiment
(focusing on senesced leaves only). Among the three parameters of leaf
flammability that we measured, interspecific variation in time to ignition
was mainly explained by specific leaf area and moisture content. Flame
duration and smoulder duration were mostly explained by leaf dry mass and
to a lesser degree by leaf chemistry, i.e. nitrogen, phosphorus and tannin
concentrations. The variation in the decomposition constant across species
was unrelated to our measures of flammability. Moreover, different
combinations of morphological and chemical leaf properties underpinned the
interspecific variation in decomposability and flammability. In contrast
to litter flammability, decomposability was driven by lignin and
phosphorus concentrations. The decoupling of flammability and
decomposability leads to three possible scenarios for species’ influence
on litter fates: (I) fast-decomposing species for which flammability is
irrelevant because there will not be enough litter to support a fire; (II)
species with slow-decomposing leaves and a high flammability; and (III)
species with slow-decomposing leaves and a low flammability. We see
potential for making use of the decoupled trait – decomposition –
flammability relationships when modelling carbon and nutrient fluxes.
Including information on leaf traits in models can improve the prediction
of fire behaviour. Herbivory is another key fate for leaves, but this
study was focused on fire and decomposition.