DOI: 10.5061/dryad.6hdr7sr00
title: Effects of plant hydraulic traits on the flammability of live fine canopy fuels in 62 Australian plant species

description: Plant species vary in how they regulate moisture and this has implications
 for their flammability during wildfires. We explored how fuel moisture is
 shaped by variation within six hydraulic traits: saturated moisture
 content, cell wall rigidity, cell solute potential, symplastic water
 fraction and tissue capacitance. Using pressure-volume curves, we measured
 these hydraulic traits distal shoots (i.e. twigs + leaves) in 62 plant
 species across four wooded communities in south-eastern Australia. For a
 subset of 30 of those species, we also measured hydraulic traits of twigs
 using moisture-release curves. Moisture content of fine fuels was then
 estimated for circumstances typical of fire weather. These projections
 were made assuming that under the hot, dry, windy conditions typical of
 large wildfires, leaves and fine twigs would function at internal water
 pressures close to wilting point (i.e. turgor loss point, TLP). The effect
 of different moisture contents at TLP on ignition time was then modelled
 using a fully mechanistic, finite element model of biomass ignition based
 on standard principles of physical chemistry. We also measured predawn
 water potential, an indication of plant access to soil water that is
 influenced by root architecture. These data were used to model how root
 traits influence fuel moisture and ignition time.
description: For full details of methods, see Scarff et al (2021). Effects of
 plant hydraulic traits on flammability of live fine canopy
 fuels. <em>Functional Ecology</em>, in press, and the
 associated Supplementary Information.
description: This archive contains hydraulic trait data for 62 species of
 vascular plant from south-eastern Australia. The sheet
 'Metadata' lists abbreviations for response variables, codes
 used to classify species regeneration strategy and species
 codes. The sheet 'Raw data, shoots' shows
 pressure volume curves for distal shoot samples. The
 sheet 'Trait data by species, shoots' records hydraulic trait
 data for distal shoots, and regeneration strategy. The
 sheet 'Trait data by species, twigs' records hydraulic trait
 data for twigs, showing results for 30 of the 62 species addressed in the
 shoot study. The sheet 'Trait effect on
 moisture' shows how the range in water loss associated with variation
 in hydraulic traits, can be expressed as a range in water content at TLP
 or at midday. In turn, this range in moisture content is expressed as a
 range in ignition time for a leaf or twig. See Methods section
 'Numerical model of leaf ignition' in main paper (Scarff et al
 2021 Functional Ecology) for details. The sheet consists of 3 parts: A, B
 and C. These address calculations for traits that modify water loss (A),
 for MC<sub>100</sub> (B) and for ψ<sub>PD</sub>
 (C). The sheet 'Ignition model validation'
 shows how the numerical model of biomass ignition predicted ignition times
 for leaves. Part A shows predictions for 43 species tested by Gill
 & Moore (1996), based on leaf thickness, density and moisture
 content. Part B shows how ignition time changes as leaf thickness and
 moisture content are systematically varied.