The chance discovery of an unusual Ficus specimen near Katherine in the Northern Territory prompted an investigation into hybridisation between two morphologically distinct endemic Australian sandpaper figs, Ficus aculeata A.Cunn. ex Miq. and F. coronulata Miq. In this study, genome-wide scans and morphological measurements were used to investigate the perceived hybridisation by using herbarium and freshly collected samples. Most of the putative hybrids displayed a wide variety of intermediate morphology and some individuals had characteristics consistent with the description of a third species, F. carpentariensis D.J.Dixon. Both genomic and morphometric results provided evidence of naturally occurring hybridisation events within Ficus. Additionally, the findings from this study showed possible taxonomic issues within the Northern Australian sandpaper figs that warrant further investigation.
Leaf flammability is a functional trait that can vary widely among plant species. At present, however, the effects that increasing radiant heat flux have on variation in leaf flammability among species are not well understood. Yet, such effects could have important implications for wildfire models that take into account species' differences in flammability.• We examined how five leaf flammability attributes spanning ignitibility (times to incandescence and flaming), sustainability (incandescence and flame durations) and combustibility (proportion of leaves entering flaming combustion) responded to increasing radiant heat fluxes (29.6 to 96.6 kWm −2 ) in 10 species of fire-prone woodlands.• As radiant heat flux increased, times to incandescence and flaming became significantly faster and proportions of leaves entering flaming combustion became significantly higher. In contrast, incandescence duration became significantly shorter at high radiant heat flux. Differences among species in these flammability attributes decreased with increasing radiant heat flux, with species becoming significantly more similar to each other. Differences among species in flame duration, however, were not significantly affected by increasing radiant heat flux, with leaf flaming durations in each species remaining relatively fixed across the radiant heat flux gradient.• Our findings show that leaf flammability is significantly affected by increasing radiant heat flux. We suggest that of the flammability attributes assessed in our study, flame duration is the most informative to include in wildfire models which explicitly consider species' flammability, given that differences among species in flame duration are maintained across a radiant heat flux gradient.
With recent and predicted increases in the frequency and intensity of wildfires, there is a pressing need for mitigation strategies to reduce the impacts of wildfires on human lives, infrastructure and biodiversity. One strategy involves the use of low-flammability plants to build green firebreaks at the wildland–urban interface. It is common, however, to encounter uncertainty in a diverse range of stakeholders about the concept of flammability as it applies to plants, which may impede efforts to identify suitable low-flammability plant species. Here, we provide an approach to identify low-flammability plant species that integrates three fundamental and relatively easy-to-measure plant-flammability attributes – ignitibility, sustainability and combustibility – in a way that removes confusion about the concept of plant flammability. These three intrinsic flammability attributes relate to each other such that an ideal low-flammability species is one that is slow to ignite, sustains burning for a short period of time and combusts with low intensity. Consideration is then given to secondary attributes of plants critical to the selection of low-flammability plants, including attributes that influence the volume of fuel available for fires and the vertical and horizontal spread of fires. More work is urgently needed across the world to identify low-flammability plant species using standardised measurement protocols, and our integrated approach provides a transparent way to ensure we are selecting the right species, for the right location, in green firebreaks.
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