Jamie Kirkpatrick argued that biodiversity conservation in fragmented landscapes is hampered by misapplication of island biogeography theory, which posits that species richness of islands is positively related to island size and negatively related to island isolation. The species-level mechanisms underpinning these relationships were later elaborated in metapopulation theory. Several empirical manipulations from around the world supported the predicted outcomes of fragmentation processes. The corollary, that small habitat fragments lose species, lack viability and thus contribute little to biodiversity conservation, has become a pervasive paradigm in design of protected area networks, environmental regulation and impact assessment, and ecological restoration practice. Jamie challenged the foundations of these applications as an 'ecological myth', citing evidence from his studies in Tasmania's midlands on the enduring conservation values of small fragments. Here, we investigated patterns and decadal-scale changes in plant species diversity in woodland fragments on the Cumberland plain, a southeastern Australian landscape fragmented by land clearing for agriculture similar to 200 years ago and now undergoing rapid urbanisation. After accounting for variations in pre-survey rainfall and sampling season, we found that, changes in species composition, loss of native species or addition of non-native species over 20 years were largely independent of patch size and connectivity, despite possible signals of past effects of patch geometry. Relationships varied between land tenure types, suggesting a dependence on land management legacies or biophysical properties that vary between tenures. Our study adds to the large, diverse and reliable body of empirical evidence that small isolated patches can have conservation values that larger more connected patches do not. We recommend policies and practices that: (1) embody a strong evidenced-based approach to conservation, development and restoration decisions that accounts for site-specific contributions of patches to landscape biodiversity, irrespective of patch size and connectivity; and (2) reject 'ecological myths' derived from misapplications of ecological theory that ignore its fundamental assumptions.

Insights into declines in ecosystem resilience and their causes and effects can inform preemptive action to avoid ecosystem collapse and loss of biodiversity, ecosystem services, and human well-being. Empirical studies of ecosystem collapse are rare and hampered by ecosystem complexity, nonlinear and lagged responses, and interactions across scales. We investigated how an anthropogenic stressor could diminish ecosystem resilience to a recurring perturbation by altering a critical ecosystem driver. We studied groundwater-dependent, peat-accumulating, fire-prone wetlands known as upland swamps in southeastern Australia. We hypothesized that underground mining (stressor) reduces resilience of these wetlands to landscape fires (perturbation) by diminishing groundwater, a key ecosystem driver. We monitored soil moisture as an indicator of ecosystem resilience during and after underground mining. After landscape fire, we compared responses of multiple state variables representing ecosystem structure, composition, and function in swamps within the mining footprint with unmined reference swamps. Soil moisture declined without recovery in swamps with mine subsidence (i.e., undermined), but was maintained in reference swamps over 8 years (effect size 1.8). Relative to burned reference swamps, burned undermined swamps showed greater loss of peat via substrate combustion; reduced cover, height, and biomass of regenerating vegetation; reduced postfire plant species richness and abundance; altered plant species composition; increased mortality rates of woody plants; reduced postfire seedling recruitment; and extirpation of a hydrophilic animal. Undermined swamps therefore showed strong symptoms of postfire ecosystem collapse, whereas reference swamps regenerated vigorously. We found that an anthropogenic stressor diminished the resilience of an ecosystem to recurring perturbations, predisposing it to collapse. Avoidance of ecosystem collapse hinges on early diagnosis of mechanisms and preventative risk reduction. It may be possible to delay or ameliorate symptoms of collapse or to restore resilience, but the latter appears unlikely in our study system due to fundamental alteration of a critical ecosystem driver. Efectos de las interacciones entre los estresantes antropogénicos y las perturbaciones recurrentes sobre la resiliencia y el colapso de los ecosistemas.

Aim Megafire events generate immediate concern for wildlife and human well-being, but their broader ecological impacts likely extend beyond individual species and single fire events. In the first mechanistic study of fire effects focussed on ecosystems, we aimed to assess the sensitivity and exposure of ecosystems to multiple fire-related threats, placing impacts in the context of changing fire regimes and their interactions with other threats. Location Southern and eastern Australia. Time period 2019-2020. Major species studied Australian ecosystems. Methods We defined 15 fire-related threats to ecosystems based on mechanisms associated with: (a) direct effects of fire regime components; (b) interactions between fire and physical environmental processes; (c) effects of fire on biological interactions; and (d) interactions between fire and human activity. We estimated the sensitivity and exposure of a sample of 92 ecosystem types to each threat type based on published relationships and spatial analysis of the 2019-2020 fires. Results Twenty-nine ecosystem types assessed had more than half of their distribution exposed to one or more threat types, and only three of those were listed as nationally threatened. Three fire-related threat types posed the most severe threats to large numbers of ecosystem types: high frequency fire; pre-fire drought; and post-fire invasive predator activity. The ecosystem types most affected ranged from rain forests to peatlands, and included some, such as sclerophyllous eucalypt forests and heathlands, that are traditionally regarded as fire-prone and fire-adapted. Main conclusions Most impacts of the 2019-2020 fires on ecosystems became apparent only when they were placed in the context of the whole fire regime and its interactions with other threatening processes, and were not direct consequences of the megafire event itself. Our mechanistic approach enables ecosystem-specific management responses for the most threatened ecosystem types to be targeted at underlying causes of degradation and decline.

Australia's dry sclerophyll forests are fire-prone ecosystems characterised by a diverse and spectacular sclerophyll flora and occurring on infertile soils. In the east, they are distributed in an arc from south-east Queensland to the Adelaide region and in the eastern half of Tasmania. In the west, they are restricted to the south-west corner on the Darling scarp and Swan coastal plain. The distribution of dry sclerophyll forests has historically been interpreted as reflecting patterns of seasonal drought, but this theory has long been discarded in favour of one of edaphic control (nutrient-poverty). Both theories exemplify classical resource-based models of evolutionary or ecological convergence. Neither, however, can adequately account for patterns in the structure, floristics and dynamics of fire-prone ecosystems. In this chapter, we examine the influence of climate and geology on the distribution of dry sclerophyll forest in terms of both resource constraints and as drivers of fire-regimes. Climate, through its control of primary productivity and fire weather, and soils, which influence flammability via the expression of sclerophylly, underpin biogeographical patterns in the frequency, intensity and seasonality of fires, and thus, potentially, the distribution of dry sclerophyll forests. Fire is a primary focus of management and necessitates finding a delicate balance between fuel reduction and biodiversity conservation. Dry sclerophyll forests are relatively resilient to invasion by alien plant species but many species are susceptible to fungal pathogens such as Phytophthora cinnamomi. The most serious threats to dry sclerophyll forests in the future include spread of disease and changes in rainfall patterns and fire regimes associated with anthropogenic climate change.

Anthropogenic climate change is a key threat to global biodiversity. To inform strategic actions aimed at conserving biodiversity as climate changes, conservation planners need early warning of the risks faced by different species. The IUCN Red List criteria for threatened species are widely acknowledged as useful risk assessment tools for informing conservation under constraints imposed by limited data. However, doubts have been expressed about the ability of the criteria to detect risks imposed by potentially slow-acting threats such as climate change, particularly because criteria addressing rates of population decline are assessed over time scales as short as 10 years. We used spatially explicit stochastic population models and dynamic species distribution models projected to future climates to determine how long before extinction a species would become eligible for listing as threatened based on the IUCN Red List criteria. We focused on a short-lived frog species (Assa darlingtoni) chosen specifically to represent potential weaknesses in the criteria to allow detailed consideration of the analytical issues and to develop an approach for wider application. The criteria were more sensitive to climate change than previously anticipated; lead times between initial listing in a threatened category and predicted extinction varied from 40 to 80 years, depending on data availability. We attributed this sensitivity primarily to the ensemble properties of the criteria that assess contrasting symptoms of extinction risk. Nevertheless, we recommend the robustness of the criteria warrants further investigation across species with contrasting life histories and patterns of decline. The adequacy of these lead times for early warning depends on practicalities of environmental policy and management, bureaucratic or political inertia, and the anticipated species response times to management actions.

AimMire ecosystems are threatened by global climate change but have important roles in biodiversity conservation, carbon storage, landscape-scale hydrological function and in providing ecosystem services. We aimed to: (1) estimate change in areas environmentally suitable for mires under future climates; (2) evaluate the sensitivities of projected change to uncertainties in future climate and model structure; (3) evaluate the effect of global mitigation actions on distribution change; (4) identify potential climate refuges for future adaptation actions.MethodsWe developed and evaluated correlative bioclimatic models for an Australian mire ecosystem by: (1) selecting environmental predictors representing ecological processes that mediate ecosystem occurrence and dynamics; (2) using a high-performance modelling algorithm; (3) quantifying predictive performance by cross-validation; (4) cross-checking responses to predictor variables between different algorithms; (5) comparing the modelled responses with expected mechanistic responses; (6) evaluating extrapolation risks by quantifying the deviation between future and current environmental domains of the study area and by assessing the temporal constancy of correlations between variables; (7) using a geographically stratified cross-validation to verify spatial consistency of the model; and (8) quantifying the robustness of predictions of climate change impacts to uncertainty in both climate and ecological models.ResultsAll combinations of global circulation models and distribution model projected declines of at least 30% in both area and suitability of environments for the mire ecosystem and in projecting a contraction of range to the southwest. We identified a likely refuge in the south of the distribution and two less certain, emerging areas of suitable environment west and south of the current distribution.Main ConclusionsWe conclude that southern mire ecosystems are highly susceptible to climate change. Our approach will be useful for the prediction of climate impacts on other ecosystems for which there is enough knowledge to map distributions and develop plausible hypotheses about environmental factors that influence them.

The establishment of a characteristic assemblage of native species is fundamental to the restoration of natural ecosystems. Species diversity is important in aesthetic terms (restored sites must resemble reference sites) and because restored ecosystems are more likely to be functional, self-sustaining and resilient in the face of periodic environmental perturbations if they contain the full range of species growth-forms, and regeneration and nutrient acquisition guilds.

Phytophthora cinnamomi, a soil-borne pathogen that infects the roots of plants, is listed as a Key Threatening Process under Commonwealth and NSW state biodiversity legislation due to its deleterious effects on native flora. In warm temperate eastern Australia, the disease may cause insidious declines in plant species that have slow rates of population turnover, and thereby threaten their long term persistence. Phytophthora cinnamomi has been known to occur in Royal National Park since the 1970s and systematic surveys for the pathogen were carried out a decade ago. Development of effective management strategies to mitigate the impacts of the disease requires information on the spatial distribution of risks posed by the disease. In this study, we use limited disease survey data to identify areas that are most at risk. We propose and apply a simple risk model in which risks of disease impact are proportional to the product of habitat suitability for the pathogen and abundance of susceptible biota. We modelled habitat suitability of the pathogen from available survey data and found that soil landscapes and topographic variables were the strongest predictors. Susceptible flora were concentrated on sandstone plateaus. Disease risks were greatest on the sandstone plateaus and lowest in the shale gullies with intermediate levels of risk on shale ridges and the coastal sand plain. The outcomes of this spatially explicit risk assessment will help inform the development of management strategies and priorities for the disease in the Park. Our approach lends itself to broader application to conservation planning in other landscapes and to other threats to biodiversity.

We evaluated the restoration of native plant assemblages by topsoil translocation in the Hunter Valley, south‐east Australia. Species' responses were characterized by defining nine plant functional types (PFTs) based on combinations of four response mechanisms (seed bank persistence, germination cues, resprouting mechanisms, and longevity) through which species were predicted to persist or decline following translocation. The effects of community type and delay in topsoil restoration on restoration outcomes were tested in an orthogonal experiment. Changes in species' frequency were detected using Bayesian statistics with prior probabilities derived from pre‐clearing data. Few species failed to reestablish following translocation; these were offset by recruitment of other native species not detected prior to clearing. Compositional changes were more pronounced when topsoil was stockpiled (cf direct reinstatement), although there was no trend related to the period of stockpiling. The PFT response model correctly predicted the rank probability of decline in three of the nine PFTs, while a further three were correctly placed in the top ranks but in the incorrect order. Three PFTs were incorrectly ranked because the response model was incorrect. Resprouters declined more frequently than seeders; however, species with physical seed dormancy declined less frequently than those with either transient seed banks or physiological, morphological, or morpho‐physiological dormancy, irrespective of resprouting ability. Species with short juvenile periods were more likely to increase. We conclude that PFTs based on fire‐response traits represent a practical means of predicting species' responses to translocation and a basis for prioritizing species for supplementary planting.

The pace and magnitude of biodiversity loss has led to wide recognition that efforts to conserve individual species must be complemented by assessment and planning at community and ecosystem levels. Emerging protocols for assessing the conservation status of communities include as central criteria the current extent, historical reduction and contemporary rate of decline in geographic distribution. Estimation of these parameters is confronted by methodological challenges, data limitations and uncertainties that may vary from case to case. We describe an approach to these issues comprising five steps: (1) classification of the community using an analysis of data from systematic ground surveys; (2) mapping to produce a contemporary baseline distribution (1980s); (3) interpolation to produce a historical distribution (pre-European settlement); (4) interpretation of satellite imagery to update the distribution (various dates up to 2004) and (5) assessment of change in extent over historical and contemporary time scales incorporating plausible bounds of uncertainty around best estimates. The bounds can be based on areas for which image interpretation produces uncertain diagnosis of clearing and differences between credible alternative base maps of the same area. We demonstrated the approach using a case study of Coolibah–Black Box Woodland, a declining semi-arid woodland community in Australia and found that 61% (plausible range 50–67%) of the woodland community had been cleared since European settlement and that during 1998–2004 the community continued to decline on average by 135.3(±21.7)km2 each year, or 1.7(±0.3)% of each previous year’s distribution, apparently accelerating in recent years. Strengths of the approach include the use of biological data (cf. remote sensing) to distinguish the target assemblage from others, the use of historical and contemporary base lines to examine change over different time scales, and the use of bounded estimates to incorporate uncertainty into the assessment.

Offset schemes are advocated as a way that continued development and environmental restoration can be achieved concurrently. We used a simple modelling approach to evaluate proposed offsets schemes, with scenarios that required offsetting the impacts of clearing woodlands either by revegetation of cleared land or by improving the habitat value of degraded woodland. Each simulation used the attribute table of a single GIS polygon layer to obtain data and record results. We investigated the likely consequences of these schemes for three groups of species with different foraging resource requirements: shrub-dependent; canopy-dependent and old tree-dependent. Only the shrub-dependent group, whose requirements could be rapidly grown, saw increases in suitable habitat in the landscape within our 30year simulations. The habitat of the canopy-dependent group initially declined but began to increase towards the end of some simulations, while the old tree-dependent group’s habitat declined. When a simple measure of spatial configuration was considered further differences between the schemes were highlighted. The simulation results demonstrate that assessing only the eventual benefit score of a scheme can hide the losses sustained by some elements of biodiversity. We recommend this type of simple modelling approach as the first step in determining whether a proposed offsets scheme is worth investigating further. In particular, the ability to represent the scheme’s predicted consequences as maps and graphs assists decision makers in judging whether the scheme has sufficient merit to warrant a full assessment and subsequent implementation; or needs some adjustments to achieve its aims, or is seriously flawed.

Maps are important tools in natural resource management. Often, there may be multiple maps that represent the same resource, which have been constructed using very different philosophies and methods, at different scales, for different dates and areas. In such cases, conservation planners and other natural resource managers are faced with a choice of map that will best serve their decision making. However, the best available information for a given purpose is often a combination of data from a number of different source maps. In this paper we present a protocol for assessing and integrating multiple maps of vegetation for a particular area of interest. The protocol commences with a consideration of management or policy context and technical issues to determine the basic specifications for the map. It then defines and assesses a set of measurable attributes, representing the concepts of theme, accuracy, precision and currency, for all candidate maps available for compilation. The resulting ranks for accuracy, precision and currency are used to compute a suitability index, which is used to assemble a composite map from the most suitable candidate maps. The final step in the protocol is to display spatial patterns in thematic consistency, accuracy, precision and currency for the composite map. We demonstrate the application of the protocol by constructing a map that discriminates structurally intact native vegetation from cleared land for the whole of New South Wales, south-eastern Australia. The source data include 46 maps that cover various parts of the region at various scales and which were made at different dates using different methods. The protocol is an explicit and systematic method to evaluate the strengths and weaknesses of alternative data sets. It implements spatial integration in a way that promotes overall accuracy, precision and currency of map data. It also promotes transparent reporting of map limitations, to help map users accommodate risks of map errors in their decision making, and to inform priorities for future survey and mapping.

White cypress pine Callitris glaucophylla is an important native tree widespread in heavily cleared savanna woodlands of the south-east Australian wheat-sheep belt. C. glaucophylla woodlands have been the focus of vigorous debate regarding their structure and dynamics during Aboriginal times and following European settlement, and the causes of structural changes are poorly understood. Management of contemporary woodland remnants is therefore controversial, and has so far lacked a predictive, process-based approach. We sought to determine whether a simple process model with recruitment, growth and survival mediated by rainfall and competition, could accurately simulate medium-term dynamics of C. glaucophylla woodlands in which fire has typically been excluded. Model parameters were optimised using reference data from 6- to 36-year silvicultural trials in central-western New South Wales (NSW). Predictions of the calibrated model compared favourably to actual growth, survival and recruitment of C. glaucophylla in the reference data, as well as in an independent dataset not used in optimisation. We tested whether remaining differences between predictions and actual data were related to variation in site productivity (a function of moisture availability as influenced by soil and landscape factors not modelled). Growth was overestimated in low-productivity sites and underestimated in high-productivity sites. Growth predictions were improved by using site-specific expected maximum heights to reflect site productivity. We also tested whether the model and parameter set produce dynamics consistent with those observed over the last half century. Modelled growth, survival, recruitment and competition processes were consistent with data and observations in previous studies on historical dynamics and stand behaviour of C. glaucophylla. The model has a wide range of potential applications for understanding past and predicting future stand dynamics. To illustrate an application of the model to thinning, a strategy currently being implemented to manage tree densities in inland NSW, we compared predicted stand structures in simulations of different thinning treatments. The simulations showed that without careful manipulation of existing canopy cover, stands can re-fill to pre-thinning densities within relatively short periods of time.

Coastal floodplains are functionally important and highly endangered ecosystems in southeastern Australia, which have a long history of exploitation and environmental modification. In this study, we undertook a systematic survey of contemporary vegetation in two recently established nature reserves on the south coast of New South Wales and investigated historical records of the vegetation and environment to infer likely changes since European settlement. An analysis of floristic samples showed that the present-day floodplain vegetation includes a mosaic of woodlands, forests and saltmarsh/reedland (five communities) that contrast markedly in species composition and structure to eucalypt forests that occupy the surrounding hills (two communities). One hundred and forty-nine plant species were recorded in 24 0.04 ha samples within the reserves, with Poacaeae and Cyperaceae represented by the most species on the floodplain. Some parts of the floodplain contain substantial weed infestations, while other parts of the floodplain are largely free of weeds. The vegetation underwent a series of changes since the first recorded observations in 1805. At that time the floodplain included a mosaic of woodland, grassland and reedland. Native grassland now appears to be extinct as a result of subsequent clearing, intensive cattle grazing, pasture improvement and changes to drainage. A network of drains, initially constructed around 1900 and further developed in the 1960s, resulted in soil oxidation. This may have made the floodplain soils more suitable for woody plant species, but recruitment has been largely prevented by intensive cattle grazing. A recent expansion of Casuarina and Melaleuca scrub and forest is evident within the nature reserves since their dedication and exclusion of livestock in 2001, but not on adjoining properties where intensive cattle grazing continues. We conclude that the reserves include important samples of remnant floodplain vegetation and that the vegetation is in a continuing state of flux regulated by changing flood and tidal regimes and grazing regimes.

We consider the history of woodland clearing in central western New South Wales, Australia, which has led to the present highly cleared and fragmented landscape. A combined approach is used examining available historical land-use data and using regression analysis to relate the pattern of cleared and wooded areas in the recent landscape to environmental variables, taking into account the contagious nature of clearing. We also ask whether it would be possible to apply a simple simulation modelling approach to reconstruct a credible historical sequence of clearing in the study area. The historical data indicate that annual clearing rates have varied substantially in the study area and selective tree removal (ringbarking and thinning) has been common. These findings make it unlikely that a simple simulation approach would replicate the spatial and temporal sequence of woodland loss. Our regression results show that clearing patterns can be related to environmental variables, particularly annual rainfall and estimated pre-European vegetation type, but that patterns are dominated by contagion.