The 2019/20 fire season in Australia ravaged the continent at levels not seen in recorded history. Unprecedented droughts record high temperatures, and an abundance of dry biomass colluded to produce extensive and severe burns. Immediately following these fires, in some regions, came torrential downpours that caused localized flooding and erosion. This cascade of hazards both has dramatic impacts on existing plants species’ distributions and their ability to sustain viable populations under the future hazards anticipated under climate change. We assessed the impacts on 19,000+ Australian plant species to determine how the 2019/20 hazards compare to historical trends in driving biodiversity loss. We developed a rapid response initiative as a collaboration between ecologists, environmental engineers, data scientists and conservation biologists to (1) quantify the extent of burnt area across species ranges; (2) assess the risk of these cascading environmental hazards in the coming century. We generated the first comprehensive set of distribution maps for all plant species in Australia with data, as well as new environmental layers from remote sensing describing fire extent and severity, flooding, erosion, and historical and future droughts. We quantified the risk status for all Australian plant species based on their exposure to different combinations of hazards.
Results/Conclusions
The 2019 drought was the worst in the precipitation record dating back to 1980 and the extent of fires in New South Wales was the worst in historic record dating back to 2003. 1,335 species assessed, were listed under federal protection (FP), and 4,622 were listed under state-based protection. 8% of FP taxa had more than 50% of their range burned during the 2019-2020 fire season. 155 FP taxa were prioritized as having high or medium level impacts (12% of FP taxa). Of the prioritization criteria assessed, the highest proportions of FP taxa listed as high risk included fire-disease interaction (60 species) cumulative exposure to risk (50 species) and high fire severity (32 species). In New South Wales, the region hardest hit by fires, regional endemics were heavily impacted and high risk species included 132 affected by the interaction of drought and fire, 77 affected by short fire intervals, 281 affected by fire-disease interactions, 158 affected by high fire severity, and 114 affected by post fire erosion. Future droughts are expected to increase in frequency across much of the continent, implying that the 2019/20 fires may be representative of the conditions to be expected in Australia in the future.