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Aim To quantify the impact of the 2019–2020 megafires on Australian plant diversity by assessing burnt area across 26,062 species ranges and the effects of fire history on recovery potential. Further, to exemplify a strategic approach to prioritizing plant species affected by fire for recovery actions and conservation planning at a national scale. Location Australia. Methods We combine data on geographic range, fire extent, response traits and fire history to assess the proportion of species ranges burnt in both the 2019–2020 fires and the past. Results Across Australia, suitable habitat for 69% of all plant species was burnt (17,197 species) by the 2019–2020 fires and herbarium specimens confirm the presence of 9,092 of these species across the fire extent since 1950. Burnt ranges include those of 587 plants listed as threatened under national legislation (44% of Australia's threatened plants). A total of 3,998 of the 17,197 fire‐affected species are known to resprout after fire, but at least 2,928 must complete their entire life cycle—from germinant to reproducing adult—prior to subsequent fires, as they are killed by fire. Data on previous fires show that, for 257 species, the historical intervals between fire events across their range are likely too short to allow regeneration. For a further 411 species, future fires during recovery will increase extinction risk as current populations are dominated by immature individuals. Main conclusion Many Australian plant species have strategies to persist under certain fire regimes, and will recover given time, suitable conditions and low exposure to threats. However, short fire intervals both before and after the 2019–2020 fire season pose a serious risk to the recovery of at least 595 species. Persistent knowledge gaps about species fire response and post‐fire population persistence threaten the effective long‐term management of Australian vegetation in an increasingly pyric world.

LiDAR data acquired from airplanes and helicopters – known as airborne laser scanning (ALS) – are widely regarded as the gold standard for characterizing the 3D structure of forests at scale. But in the last decade, advances in unoccupied aerial vehicle (UAV) technologies have led to a rapid rise in the use of UAV laser scanning (ULS) for mapping forest structure. As both ALS and ULS data become increasingly available, they are being used to derive an ever‐growing number of metrics designed to measure different facets of canopy structure. However, which metrics can be robustly retrieved from both ALS and ULS platforms remains unclear. To address this question, we acquired coincident, high‐density ALS and ULS scans covering 115 plots (4‐ha in size) in an open‐canopy temperate ecosystem in Western Australia. Using this unique dataset, we quantified 32 canopy structural metrics related to canopy height, openness and heterogeneity, including metrics calculated directly from the point clouds and ones measured from derived canopy height models (CHM). Overall, we found that ALS and ULS‐derived metrics were strongly correlated (r2 = 0.90). However, this high degree of correlation masked considerable systematic differences between platforms. Specifically, point cloud metrics were less strongly (r2 = 0.87) correlated and had higher bias (10.7%) compared to CHM‐derived ones (r2 = 0.98; bias = 2.5%). Similarly, metrics of canopy openness and heterogeneity were less strongly correlated (r2 = 0.84 and 0.87) and exhibited greater bias (14.4 and 7.9%) than ones relating to canopy height (r2 = 0.96; bias = 3.8%). Our results indicate that only a small subset of the 32 metrics we tested were directly comparable between ALS and ULS platforms. Consequently, future efforts to combine laser scanning data across platforms and instruments should think carefully about which metrics are most appropriate, especially when working with point cloud data. Growing access to different sources of airborne LiDAR, including data acquired from airplanes, helicopters and unoccupied aerial vehicles (UAVs), is transforming our ability to capture the 3D structure of forests at scale. However, considerable uncertainty remains as to how comparable structural metrics derived from these various platforms are to each other. Using LiDAR data acquired concurrently from airplanes and UAVs across 115 sites in an open‐canopy woodland ecosystem in Australia, we tested the robustness of 32 commonly used canopy structural metrics. We show that many widely used canopy structural metrics show poor agreement between these two platforms, but were also able to identify a subset of metrics that provide a robust and ecologically intuitive way of characterizing the structure of open‐canopy forests worldwide.

The ecology of seed dispersal by vertebrates has been investigated extensively over recent decades, yet only limited research has been conducted on how suites of invasive plants and frugivorous birds interact. In this review, we examine how plant fruit traits (morphology, colour and display, nutritional quality, accessibility and phenology), avian traits (fruit handling techniques, gut passage time and effect, bird movements and social behaviour and dietary composition) and landscape structure (fruit neighbourhood, habitat loss and fragmentation and perch tree effects) affect frugivory and seed dispersal in invasive plants. This functional approach could be used to develop generic models of seed dispersal distributions for suites of invasive plant species and improve management efficiencies. Four broad research approaches are described that could direct management of bird-dispersed invasive plants at the landscape scale, by manipulating dispersal. First, research is needed to quantify the effect of biological control agents on dispersal, particularly how changes in fruit production and/or quality affect fruit choice by frugivores, dispersal distributions of seed and post-dispersal processes. Second, we explore how seed dispersal could be directed, such as by manipulating perch structures and/or vegetation density to attract frugivorous birds after they have been foraging on invasive plant fruits. Third, the major sources of seed spread could be identified and removed (i.e. targeting core or satellite infestations, particular habitats and creating barrier zones). Fourth, alternative food resources could be provided for frugivores, to replace fruits of invasive plants, and their use quantified.

The Southwest Australian Floristic Region (SWAFR) supports an exceptional number of threatened and data-deficient flora. In this study, we: (i) collated statistics on the number, listing criteria and tenure of occurrence of threatened and data-deficient flora; (ii) conducted spatial and biogeographic analyses to address questions concerning patterns of diversity of threatened and data-deficient flora relative to the whole flora and evolutionary and threat drivers; and (iii) examined whether threatened and data-deficient flora richness is evenly distributed across plant lineages. We found that although threatened and data-deficient flora occurred across the breadth of the SWAFR, high richness was concentrated in a limited number of locations, which were not always strongly aligned with areas of higher land transformation. Data-deficient flora demonstrated different spatial patterns of occurrence to threatened flora. Approximately 70% of the populations of threatened and data-deficient flora occurred outside of lands managed primarily for conservation. Both evolutionary history and contemporary threats contribute to the current status and distribution of diversity of the threatened and data-deficient flora, with evolutionary history playing a significant role in predisposing a portion of the flora to having population traits that result in those flora meeting IUCN Red List criteria, along with ecological traits that predispose some to specific novel threats. An understanding of the distribution of species and threats, flora traits, and how these traits mediate susceptibility to threats, offers one potential way forward for an initial assessment of which of the 1819 data-deficient flora may be most at risk of extinction.

Woody debris plays an important role in many ecosystem functions, including nutrient and carbon cycling, providing substrates for plant recruitment and habitat for fauna. Fires can affect woody debris stocks, through generating new pieces by killing or severing plant parts and consuming pre‐existing woody debris. We develop a model of woody debris dynamics with variation in time since fire and prior fire interval applicable to obligate‐seeder forests and woodlands, considering down woody debris and standing dead trees as discrete components. We then test predictions of change in woody debris derived from this model in Eucalyptus salubris woodlands in South‐Western Australia, using a multi‐century chronosequence with recent fires varying between having short (<50 yr since the previous fire) or long (>50 yr, but often much longer) prior intervals. As per our woody debris dynamics model, most attributes measured were affected by time since fire, prior fire interval, or their interaction. Woody debris biomass was greatest shortly after fire, reflecting high quantities of standing dead trees resulting from stand‐replacement disturbance. Standing dead tree density and biomass then declined with increasing time since fire, but individual dead tree size was high beyond 200 yr since fire. Down woody debris biomass remained relatively stable with time since fire, but piece size increased. Dimensions of woody debris were strongly influenced by prior fire interval, with long prior intervals resulting in pieces at least twice the size than those occurring after short prior intervals. Fire management to maximize the availability of large woody debris pieces for fauna should aim to minimize short fire intervals, while from a carbon management perspective, all fires in obligate‐seeder forests and woodlands set in train large and prolonged emissions of carbon.

Background: Fire management is a crucial part of managing ecosystems. The years since last burn (YSLB) metric is commonly used in fire planning to predict when an area might be suitable to burn; however, this metric fails to account for variable recovery due to climate variability.Aim: The aim of this study was to develop a predictor of when an area may be able to ‘carry’ fire based on observed patterns of vegetation recovery and fire occurrence that is responsive to climate variability.Methods: Fire history maps and Landsat satellite imagery within the Great Victoria Desert of Australia were used to map vegetation recovery following fire. Burn potential models were then created by calculating the distributions of YSLB and vegetation recovery values for areas that subsequently burnt.Key result: A burn potential model based on vegetation recovery is a better predictor of when an area is likely to burn than a model based on YSLB.Conclusions: A burn potential model based on vegetation recovery provides an evidence-based and dynamic assessment of whether an area is likely to burn.Implications: This approach provides a model that is responsive to climate variability that can assist fire managers in burn planning and assessing fire risk.

BackgroundUnderstanding the influence of fires on terrestrial carbon stocks is important for informing global climate models and underpinning land management-based carbon markets.AimsTo quantify biomass carbon in south-western Australia’s Great Western Woodlands – the world’s largest extant Mediterranean-climate woodland – with time-since-fire and prior fire interval.MethodsPlot-based measurement of live and dead tree and shrub size, woody debris volume and litter mass across a ~400-year chronosequence to calculate biomass carbon.Key resultsBiomass carbon increased with time-since-fire, reaching >65 Mg C ha−1, although the rate of increase declined in mature woodlands. Biomass carbon decreased after fire in these obligate-seeder woodlands, while a longer prior fire interval buffered carbon fluxes through retained large standing dead trees and fallen woody debris.ConclusionsThe current age class distribution of the ~95,000 km2 of eucalypt woodlands in the region may support ~0.453 Pg C. Further refinement of carbon estimates explicitly considering variation in woodland type and climate, a continuous woodland age distribution and soil carbon are required to underpin a carbon methodology.ImplicationsBiomass carbon would be maximised by reducing the extent of bushfires impacting woodlands, focussing on existing mature stands that support the greatest carbon stocks.

Changed fire regimes have led to declines of fire-regime-adapted species and loss of biodiversity globally. Fire affects population processes of growth, reproduction, and dispersal in different ways, but there is little guidance about the best fire regime(s) to maintain species population processes in fire-prone ecosystems. We use a process-based approach to determine the best range of fire intervals for keystone plant species in a highly modified Mediterranean ecosystem in southwestern Australia where current fire regimes vary. In highly fragmented areas, fires are few due to limited ignitions and active suppression of wildfire on private land, while in highly connected protected areas fires are frequent and extensive. Using matrix population models, we predict population growth of seven Banksia species under different environmental conditions and patch connectivity, and evaluate the sensitivity of species survival to different fire management strategies and burning intervals. We discover that contrasting, complementary patterns of species life-histories with time since fire result in no single best fire regime. All strategies result in the local patch extinction of at least one species. A small number of burning strategies secure complementary species sets depending on connectivity and post-fire growing conditions. A strategy of no fire always leads to fewer species persisting than prescribed fire or random wildfire, while too-frequent or too-rare burning regimes lead to the possible local extinction of all species. In low landscape connectivity, we find a smaller range of suitable fire intervals, and strategies of prescribed or random burning result in a lower number of species with positive growth rates after 100 years on average compared with burning high connectivity patches. Prescribed fire may reduce or increase extinction risk when applied in combination with wildfire depending on patch connectivity. Poor growing conditions result in a significantly reduced number of species exhibiting positive growth rates after 100 years of management. By exploring the consequences of managing fire, we are able to identify which species are likely to disappear under a given fire regime. Identifying the appropriate complementarity of fire intervals, and their species-specific as well as community-level consequences, is crucial to reduce local extinctions of species in fragmented fire-prone landscapes.

1. Understanding ecosystem responses to disturbance is important for effective management of biodiversity. Observed relationships between time since disturbance and diversity have taken a variety of forms, only some of which are explicitly predicted in models of vegetation succession. This makes generalization and predictions for specific communities difficult. 2. Negative relationships have been the predominant diversity response to time since fire in fire-prone Mediterranean-climate ecosystems; however, few studies have analysed responses in infrequently burnt ecosystems such as Mediterranean-climate woodlands dominated by fire-sensitive trees. We used a space-for-time approach and multiple stand-ageing techniques (Landsat imagery, growth ring counts and growth ring–size relationships) to characterize diversity and compositional changes with time since fire (3–370+ years) in fire-sensitive Eucalyptus salubris woodlands in south-western Australia. 3. Species density and Pielou's evenness showed an overall 'U'-shaped response to time since fire, although variability between plots was considerable. Plant functional type and species composition differed with time since fire, with greater richness and cover of ground layer, and 'long dispersal potential' functional types with increasing time since fire. Conversely, there was an early or intermediate peak in taller and 'short dispersal potential' functional types. 4. We propose that the unusual 'U'-shaped diversity–time since fire relationship is driven by competitively dominant tree and shrub layers having maximum cover at intermediate times since fire. Subdominant functional types were able to exploit lower levels of competition in the immediate post-fire period and after density-dependent thinning of the trees and shrubs. 5. Synthesis and applications. Recurrent fire is not required to maintain diversity in these fire-sensitive woodlands as diversity reached a maximum in mature vegetation. Fire intervals of < c. 200 years are likely to have adverse consequences on diversity, which is of conservation concern given apparently high recent rates of occurrence of fire. Changes in diversity were not apparent when times since fire were truncated to those available from remote sensing, illustrating that space-for-time studies defined solely by remote sensing may obscure equivalent 'U'-shaped diversity–time since fire relationships.

Short fire intervals potentially drive declines in plant populations through immaturity risk—when the interval between two fires is too short to allow a plant population to develop the capacity to persist through the second fire. Through quantifying the period of time after fire for obligate-seeding species to become reproductively mature (the juvenile period), the risk of population decline under specific fire intervals can be delineated. Juvenile periods vary across space and time. We developed a model to estimate juvenile period based on environmental productivity that is applicable at a regional scale and over time with changes in climate. We compiled juvenile period data of serotinous obligate-seeder taxa across the breadth of the Southwest Australian Floristic Region (SWAFR). Environmental productivity models explained up to 76% of the variation in maximum juvenile period length. Juvenile period increased with lower precipitation, lower mean annual temperature and lower gross primary productivity, allowing spatial predictions of minimum tolerable fire intervals to conserve slow-maturing serotinous obligate-seeders across an entire floristic region. Applying juvenile period-productivity relationships to future climate scenarios indicated that for much of the SWAFR, juvenile period length is predicted to increase substantially, indicating high risk of short fire interval impacts with continuation of historic fire intervals. Using a case study of the Stirling Range National Park, we use historic fire interval data to identify locations having experienced short fire interval risk.