High-severity wildfires in temperate Australian forests have increased in extent and aggregation in recent decades (original) (raw)
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Nature Communications
Australia’s 2019–2020 ‘Black Summer’ bushfires burnt more than 8 million hectares of vegetation across the south-east of the continent, an event unprecedented in the last 200 years. Here we report the impacts of these fires on vascular plant species and communities. Using a map of the fires generated from remotely sensed hotspot data we show that, across 11 Australian bioregions, 17 major native vegetation groups were severely burnt, and up to 67–83% of globally significant rainforests and eucalypt forests and woodlands. Based on geocoded species occurrence data we estimate that >50% of known populations or ranges of 816 native vascular plant species were burnt during the fires, including more than 100 species with geographic ranges more than 500 km across. Habitat and fire response data show that most affected species are resilient to fire. However, the massive biogeographic, demographic and taxonomic breadth of impacts of the 2019–2020 fires may leave some ecosystems, particula...
Climate, 2022
In rapidly urbanizing areas, natural vegetation becomes fragmented, making conservation planning challenging, particularly as climate change accelerates fire risk. We studied urban forest fragments in two threatened eucalypt-dominated (scribbly gum woodland, SGW, and ironbark forest, IF) communities across ~2000 ha near Sydney, Australia, to evaluate effects of fire frequency (0–4 in last 25 years) and time since fire (0.5 to >25 years) on canopy structure, habitat quality and biodiversity (e.g., species richness). Airborne lidar was used to assess canopy height and density, and ground-based surveys of 148 (400 m2) plots measured leaf area index (LAI), plant species composition and habitat metrics such as litter cover and hollow-bearing trees. LAI, canopy density, litter, and microbiotic soil crust increased with time since fire in both communities, while tree and mistletoe cover increased in IF. Unexpectedly, plant species richness increased with fire frequency, owing to increased shrub richness which offset decreased tree richness in both communities. These findings indicate biodiversity and canopy structure are generally resilient to a range of times since fire and fire frequencies across this study area. Nevertheless, reduced arboreal habitat quality and subtle shifts in community composition of resprouters and obligate seeders signal early concern for a scenario of increasing fire frequency under climate change. Ongoing assessment of fire responses is needed to ensure that biodiversity, canopy structure and ecosystem function are maintained in the remaining fragments of urban forests under future climate change which will likely drive hotter and more frequent fires.
Quantifying the impact of severe bushfires on biodiversity to inform conservation
2020
The unusually severe 2019-2020 Australian bushfire season destroyed large areas of habitat along the southeastern coast. We assess the differences between this fire season and previous ones to understand their impacts and potential recovery. We used thermal satellite data to quantify the extent of eastern Australian bushfires from 2012-2020. During the 2019-2020 anomalous fire season, 134 mega-fires, each over 10,000 ha, burned 62.5% of the total affected area, including critical forested landscapes. Previous fire seasons were characterized by smaller, scattered fires in mostly non-forested areas. The anomalous fire season had direct negative impacts on wildlife including grey-headed flying foxes, which experienced substantial declines in immediately available foraging forest habitat, particularly key winter resources. We identified important areas for managing wildlife resources and supporting ecosystem health in the coming decades. Our research also identifies key monitoring areas...