What might ecosystems look like following substantial global change? We considered change by 2100 as potentially including the following: 4°C of global warming and >800 ppm CO2, with associated changes in extreme weather events; cessation of livestock grazing owing to meat and milk being replaced by cell-culture products; and capacity to selectively suppress particular species by using gene technologies. Future scenarios for four different Australian ecosystems were considered in relation to these drivers. Scenarios were formulated as state-and-transition (ST) diagrams. Some common themes emerged. (1) Increased extreme fire weather will shorten intervals between hot fires, unless fire control can somehow become much more effective. This will strongly affect vegetation structure and species persistence. (2) Warming by 4°C will displace many plant species from their present-day temperature envelopes. There is a major difficulty in forecasting the consequences, because solid evidence is rarely available about what controls species range boundaries. Is it physiological tolerance, or competition, or susceptibility to pathogens, or something else? (3) We need urgently to decide how much to try to support species in their present locations, versus how much to assist them to move polewards or uphill. (4) Certain species can strongly shape ecosystem structure by influencing fire or successional regimes. Gene technology for suppressing selected invasive species would have potential for improved ecosystem management. (5) If livestock grazing declines, this will interact strongly with future fire regimes and will also make lands available where future ecosystems can be deliberately constructed. These themes apply globally as well as in Australia. ST methodology is set to underpin nature-positivity assessments in Australia. In a changing world, measuring nature-positivity by similarity to past ecosystem states may no longer be helpful. Hence, there is value in building ST diagrams that include potential future states.

Context Managing widespread invasive plants to support biodiversity conservation is a significant challenge that requires weed control methods that have lesser impacts on co-occurring native species than ongoing weed invasion. African lovegrass (Eragrostis curvula) is a perennial grass invasive in many regions globally. There is a lack of effective control options, particularly in diverse native vegetation where application of broad-spectrum herbicide has risks of unacceptable off-target impacts. Aims We tested the effectiveness of flupropanate (sodium 2,2,3,3-tetra-fluoropropionate) in controlling African lovegrass in a conservation context in Mediterranean-climate south-western Australia, testing two application rates and measuring target and off-target impact. Methods Cover and condition (alive or dead) of plant species were measured in replicate plots in a ‘before-after-control-impact’ design. A small sample of endangered Grevillea curviloba individuals was deliberately treated with flupropanate. Key results Flupropanate significantly reduced African lovegrass cover, with greater reduction at the higher application rate. No significant off-target effects could be detected at a community or plant functional group level nor in the deliberate exposure of G. curviloba. Conclusions The results of this study indicate that flupropanate is effective in controlling African lovegrass in conservation settings in south-western Australia, including where G. curviloba is present. These findings contribute to the growing body of knowledge on the use of flupropanate for invasive grass management. Implications Possible off-target impacts on a single species in this study, and stronger evidence from other sources, suggest that robust testing of the susceptibility of conservation-listed flora to flupropanate should precede application in the habitat of these species.

The Full Carbon Accounting Model (FullCAM) simulates carbon (C) pools of live biomass, standing dead mass, debris and soil, the flows among them and the atmosphere, and the influences of fire and harvesting disturbances under Australian conditions. It is regularly used by governments, landowners, companies and researchers, at continental, regional and local scales. Recently, FullCAM was calibrated for seven categories of native tropical savanna vegetation. However, for non-savanna native vegetation, calibrated parameters are available for only two general vegetation categories, based on whether the annual rainfall exceeds or falls below 500 mm. These two categories are too broad to capture the large range of growth conditions, vegetation structures and species assemblages that occur across Australia’s native woody vegetation. Here, our objective was to improve FullCAM’s ability to model variation in C pools and post-disturbance recovery among eight native vegetation categories, from shrublands to rainforests, for which there were differences in biomass allocation, litterfall and/or decomposition. To do this, we calibrated FullCAM for each vegetation type, including 14 parameters that were calculated directly from field observations and 17 that were calibrated using a dataset containing about 9300 field plots with measurements of at least one woody vegetation C stock. New parameters (compared with the two general parameter sets) reduced bias from 77 to 25 % (averaged across C stocks), and root mean square error from 44 to 30 Mg C ha-1. Model accuracy could be further improved (i) by focusing on sites with a known disturbance history, (ii) calibrating as many vegetation categories as possible (instead of eight categories generalising across many species), and (iii) adding more detail to growth calculations to quantify factors that may not be adequately represented by FullCAM’s growth equation.

Wildfires play a major role in shaping the structure and dynamics of many woody ecosystems, with growing concerns that their frequency and intensity are increasing with climate change. However, we lack an understanding of how canopy structure recovers after wildfires, which limits our ability to forecast the long-term impacts of these disturbances on key ecosystem functions such as carbon storage and biodiversity. Using airborne laser scanning data acquired across a 450 year chronosequence of time since fire, we modelled the recovery trajectory of canopy 3D structural diversity across the largest temperate woodland on Earth in Western Australia. We found that canopy height, cover and heterogeneity recovered at varying rates and followed distinct trajectories. Canopies became taller, denser and more vertically homogeneous during the initial 100-150 years following fire. Subsequently, height growth plateaued while canopy cover continuously decreased for several centuries, leading to open and spatially heterogeneous structures in old-growth woodlands. The highly predictable nature of these structural recovery trajectories following wildfires allowed us to develop robust models for mapping stand age based on structural features. Our study paves the way for leveraging emerging remote sensing technologies to track ecosystem recovery from disturbance, thereby guiding management and restoration interventions at scale.

Context For plant species that have evolved in fire-prone environments, declines after wildfires are often driven by the combination of fire and other threatening processes. Mitigating the impacts of these threatening processes can sometimes effectively support post-fire population recovery. Aims We test the effectiveness of: (1) phosphite application to mitigate Phytophthora dieback; (2) fencing to exclude browsing by mammalian herbivores; and (3) translocation to sites where threats can be practically managed, for conservation of threatened flora affected by wildfires in 2018 and 2019 in the Stirling Range (Koi Kyeunu-ruff), south-western Australia. Methods Survival of Phytophthora-susceptible flora was compared in repeatedly sampled plots from prior to and after wildfire and ± recurrent phosphite application. Survival and growth of browsing-susceptible flora was compared post-fire in fenced and control plots. Survival, growth and flowering was compared between wild populations recruiting after wildfire and translocated populations. Key results Phosphite application increased survival of most Phytophthora-susceptible flora. Fencing led to greater growth and often increased survival. Translocated populations, with supplemental water, had greater growth rates and earlier flowering than wild populations, and a non-significant trend for higher survival. Conclusions These findings provide strong evidence supporting continuation of phosphite application, herbivore exclusion and translocation for post-fire recovery of the threatened flora of the Stirling Range. Implications With increasing wildfire extent, frequency and impact across the globe, successful management of non-fire threats will be crucial for post-fire conservation of threatened flora, with the approaches proving effective in this study likely to have conservation value elsewhere.

AbstractLiDAR 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.

With large wildfires becoming more frequent1,2, we must rapidly learn how megafires impact biodiversity to prioritize mitigation and improve policy. A key challenge is to discover how interactions among fire-regime components, drought and land tenure shape wildfire impacts. The globally unprecedented3,4 2019-2020 Australian megafires burnt more than 10 million hectares5, prompting major investment in biodiversity monitoring. Collated data include responses of more than 2,000 taxa, providing an unparalleled opportunity to quantify how megafires affect biodiversity. We reveal that the largest effects on plants and animals were in areas with frequent or recent past fires and within extensively burnt areas. Areas burnt at high severity, outside protected areas or under extreme drought also had larger effects. The effects included declines and increases after fire, with the largest responses in rainforests and by mammals. Our results implicate species interactions, dispersal and extent of in situ survival as mechanisms underlying fire responses. Building wildfire resilience into these ecosystems depends on reducing fire recurrence, including with rapid wildfire suppression in areas frequently burnt. Defending wet ecosystems, expanding protected areas and considering localized drought could also contribute. While these countermeasures can help mitigate the impacts of more frequent megafires, reversing anthropogenic climate change remains the urgent broad-scale solution.

Background Understanding the influence of fires on terrestrial carbon stocks is important for informing global climate models and underpinning land management-based carbon markets. Aims To 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. Methods Plot-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 results Biomass 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. Conclusions The 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. Implications Biomass carbon would be maximised by reducing the extent of bushfires impacting woodlands, focussing on existing mature stands that support the greatest carbon stocks.

Context Soil nutrient limitations characterise savanna soils globally and are one of several constraints to establishing productive tree plantations and enhancing economic opportunities in tropical regions. Fertilisation offers an approach to overcome soil nutrient limitations to maximise tree growth and health, but requires research on nutrient contents, composition, rates and methods of delivery in the context of soil characteristics. Aims To determine the optimal contents, rates and methods of application of fertiliser to maximise the growth and health of the plantation timber species Pinus caribaea on low fertility savanna soils. Methods Factorial field experiments tested growth responses to applications of phosphorus (P), nitrogen (N) and sulfur (S) on three soils near Darwin, Australia. Further experiments tested effects of zinc (Zn), copper (Cu) and potassium (K) application and small-scale variation in soil characteristics on tree performance. Key results Positive growth responses to P, N and S were recorded, yet unhealthy trees developed, particularly in better-performing treatments. Second phase experiments addressing potential causes of ill health confirmed Zn limitations. Intense spatial soil sampling demonstrated substantial variation in cation exchange capacity and composition over short distances. Conclusions Nutrient additions to enhance plantation tree growth will need to encompass minor and trace elements in addition to N, P and S, specifically Zn, and consider the mechanism of application. Implications Small-scale variability in cation exchange capacity and composition indicates that optimal fertilisation rates will vary spatially, and that soil sampling for site characterisation would be more accurate with replicated dispersed samples.

The global decline in the extent and condition of ecological communities has resulted in an increasing demand for recovery and conservation plans. Conservation plans for ecological communities require a management framework with measurable, time-bound objectives, a targeted management strategy, and indicators that enable actions to be evaluated in relation to objectives. Methods that allow for the transfer of knowledge among similar systems and facilitate consistent and comparable plans are essential, especially when resources are constrained. We describe a process to streamline the development of conservation plans by combining functionally similar community sub-types into a multi-community State and Transition Model. We demonstrate this approach in a case study where we use the combined expertise of Australian ecologists to build a multi-community State and Transition Model for eucalypt woodlands of southern Australia – an ecosystem which occupies a vast geographical range across temperate Australia and includes many distinct vegetation communities, a growing number of which are endangered or threatened. We identify commonalities and differences among three broad woodland sub-types including a set of eight general condition states, a list of drivers of transitions among condition states, and the uncertainties and time-frames associated with each transition. Two key findings across all models are that management is state-dependent, and transition directly to the ‘Exemplar’ state from any other state is considered highly unlikely. Other examples of State and Transition Models in the literature are focused on single communities or a significantly smaller scale, and this is the first attempt to construct a nationally relevant multi-community State and Transition Model via a structured and consultative process. Based on this case study, we propose a repeatable protocol for developing multi-community State and Transition Models. This process could improve and streamline the development of robust conservation plans for threatened ecological communities more broadly.

Traits with intuitive names, a clear scope and explicit description are essential for all trait databases. The lack of unified, comprehensive, and machine-readable plant trait definitions limits the utility of trait databases, including reanalysis of data from a single database, or analyses that integrate data across multiple databases. Both can only occur if researchers are confident the trait concepts are consistent within and across sources. Here we describe the AusTraits Plant Dictionary (APD), a new data source of terms that extends the trait definitions included in a recent trait database, AusTraits. The development process of the APD included three steps: review and formalisation of the scope of each trait and the accompanying trait description; addition of trait metadata; and publication in both human and machine-readable forms. Trait definitions include keywords, references, and links to related trait concepts in other databases, enabling integration of AusTraits with other sources. The APD will both improve the usability of AusTraits and foster the integration of trait data across global and regional plant trait databases.

Context Widespread soil nutrient limitations in savanna soils typically constrain plantation tree growth, and hence limit economic opportunities in tropical regions. Fertilisation offers an approach to overcome soil nutrient limitations, but requires research on nutrient contents and rates to maximise plant growth while avoiding nutrient imbalances that have stunted plant growth under some fertiliser regimes. Aims To test the hypothesis that multiple nutrient limitations exist in savanna soils, with nutrient deficiencies exposed in sequence with fertiliser addition. Methods Factorial field experiments tested the growth of the plantation timber species African mahogany (Khaya senegalensis) to applications of phosphorus, potassium, nitrogen and minor and trace elements (referred to as the T treatment) on a kandosol soil near Darwin, Australia. Key results Under high stocking rates to induce deficiencies sooner through utilisation of a high proportion of the available nutrient capital, positive responses and interactions to all four main treatments were recorded. There were step-wise responses to phosphorus, potassium, nitrogen and the T treatment. Treatments with greater mean tree growth were more uniform than lesser-growing treatments, even though the largest and smallest individuals were similar across treatments. Conclusions Consistent with our hypothesis, correcting one soil nutrient deficiency exposed another in sequence as nutrient reserves were depleted in a drying soil. Variation in tree performance across plots indicates that testing of soil nutrients and fertiliser responses need to be assessed in replicate and dispersed samples. Implications Khaya senegalensis demonstrated potential for plantation use in northern Australia with minimal mortality from termites and other causes, if supported with broad-spectrum fertilisation balanced to match plant growth and water availability.

Australia's Great Western Woodlands are the largest intact temperate woodland ecosystem on Earth, spanning an area the size of the average European country. These woodlands are part of one of the world's biodiversity hotspots and, despite subsisting on just 200-400 mm of rainfall a year, can store considerable amounts of carbon. However, they face growing pressure from a combination of climate change and increasingly frequent and large wildfires, which have burned over a third of these slow-growing, fire-sensitive woodlands in last 50 years alone. To develop conservation strategies that bolster the long-term resilience of this unique ecosystem, we urgently need to understand how much old-growth woodland habitat remains intact and where it is distributed across this vast region. To tackle this challenge, we brought together data from an extensive network of field plots distributed across the region and combined this with information on vegetation 3D structure derived from drone, airborne and spaceborne LiDAR. Using this unique dataset, we developed a novel modelling framework to generate the first high-resolution maps of woodland tree size and age structure across the entire region. We found that 41.2% of the woodland habitat is covered by old-growth stands, equivalent to an area of approximately 39,187 km2. Only 10% of these old-growth woodlands fall within current protected areas managed by the state government. Instead, most remaining old-growth woodlands are found either within the Ngadju Indigenous Protected Area (26.9%) or outside of formal protected areas on leaseholds and privately owned lands (57.2%). Our maps of woodland size and age structure will help guide the targeted management and conservation of the Great Western Woodlands. Moreover, by developing a robust pipeline for integrating LiDAR data from multiple platforms, our study paves the way for mapping the 3D structure and carbon storage of open and heterogeneous woodland ecosystems from space.

Context and challenges center dot Many ecological communities (ECs) are in decline due to the impacts of inappropriate fire regimes and other threatening processes, many of which compound the impacts of fire. center dot Although Australian legislation, and that of most states/territories, provides for listing of ECs as threatened ( TECs), national assessment of the impacts of the 2019-20 wildfires on ECs is constrained by inconsistent EC definition, classification and mapping across jurisdictions. center dot Of TECs that were nationally listed as threatened prior to the 2019-20 wildfires, three had > 40% of their distributions burnt, and another three had 20- 40% of their extent burnt. Of a broader group of 92 fire-impacted ECs, including many listed as threatened by state jurisdictions, five had more than 90% of their extent burnt and 26 had more than half of their extent burnt. center dot The impacts of fire on ECs are diverse, but not always negative, and consequences can include changes in species composition (including reduced abundance of foundational species), vegetation structure, ecosystem functions, resource availability and incidence and extent of other threats. center dot The interval between successive fires is critical to community persistence, with irreversible changes ('ecosystem collapse') to disequilibrium states likely in some ECs, especially if inappropriate fire regimes disrupt life-cycle processes or transform habitats of key species. Main findings center dot Priority management responses needed to recover fire-affected ECs, and reduce the likelihood of further loss in future fires, include post-fire control of introduced herbivores; control of disease; protection of unburnt refuges from fire; protection of burnt areas from further fire; and protection of hydrological integrity. center dot Major knowledge gaps (including the mechanisms of threats, their interactions and effective control methods) constrain effective management needed for recovery. center dot Underlying these threats is a more pervasive need to reduce anthropogenic climate change. If this cannot be achieved, there will be ongoing diminution at least of rainforest, montane ash, peatland and montane heathland ecosystems.

center dot Australian plant diversity is maintained by variable fire regimes, and a single fire event - even one as large as the 2019-20 season - will have both positive and negative outcomes for species. center dot We describe how impacts were assessed after the 2019-20 fires using vulnerability assessments and evidence from field-based observations. center dot Many species are recovering well, and surprise findings of new populations are being reported across burnt areas. center dot However, the 2019-20 fires have compounded threats already active across the range of many species, including Wollemi pine (Wollemia nobilis), Stirling Range dryandra (Banksia montana) and some terrestrial orchids.

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.

The wildfires that occurred in 2019-20 affected Queensland, the Australian Capital Territory, New South Wales, Victoria, Tasmania, South Australia and Western Australia. During these fires, relevant land management agencies rapidly mobilised to support management and recovery of biodiversity. There were some shared themes that facilitated state agencies to respond appropriately at the landscape scale to wildlife and habitat recovery. These include having collated and accessible information to support decision-making on the distribution, abundance, temporal trends, ecology, and threats to species and ecosystems; the development and maintenance of internal agency technical capacity and capability to guide and support on-ground action; and having the ability to draw on external expertise and partnerships to rapidly develop inclusive and well-informed response plans. Key challenges that now form lessons for the future include developing and implementing emergency response plans and strategies that more effectively coordinate across stakeholder groups; continuously improving policies and frameworks that more effectively manage conservation priorities before, during and after wildfire events; and further developing the knowledge, capacity, planning and partnerships required to meet the challenge of conserving biodiversity with the ongoing influence of climate change on wildfire events.