Search

Aim: The trait-based vulnerability assessment (TVA) uses Boolean rules to assess species sensitivity, adaptive capacity and exposure to climate change to identify those that are climate-change vulnerable. The protocol is being increasingly used to assess climate-change impacts to a diversity of taxa, as it requires fewer data compared to niche and mechanistic models. However, uncertainty in TVA results remains unevaluated. We present the first quantitative investigation of the impacts of uncertainty on TVA, using global freshwater crayfish (574 species) as a representative data-poor taxon. Location: Global. Methods: To assess uncertainty in trait selection, we measured the completeness of information for each trait and how these contributed to the number of vulnerable species. To explore the sensitivity of TVA outcomes to arbitrary threshold selection, we randomly scored 25% species as high for quantitative traits and compared the results to the standard TVA. To investigate uncertainty in climate model selections, we tested the TVA using 66 alternative global climate scenarios. Results: Given the structural rules used in TVA, as more traits are included in the protocol, more species are identified as vulnerable to climate change. Some traits also have more dominant contributions. Species vulnerability was relatively robust to arbitrary thresholds in quantitative trait variables. The number (79–156) and identity of vulnerable species varied depending on which climate scenario was selected. Ensemble means of climate models identified fewer vulnerable species, potentially softening the extremes of individual climate models. Main conclusions: Assessors applying TVA across taxa and geographical scales should use ecological thresholds for quantitative traits, where possible; most importantly perform sensitivity analyses, including (a) critically assessing assumptions and correlations underpinning the selection of traits in different dimensions; and (b) capturing variability among climate-change models. Further research is required to fill data gaps that improve the robustness of TVA.

Aim: The koala is a widely distributed Australian marsupial with regional populations that are in rapid decline, are stable or have increased in size. This study examined whether it is possible to use expert elicitation to estimate abundance and trends of populations of this species. Diverse opinions exist about estimates of abundance and, consequently, the status of populations. Location: Eastern and south-eastern Australia Methods: Using a structured, four-step question format, a panel of 15 experts estimated population sizes of koalas and changes in those sizes for bioregions within four states. They provided their lowest plausible estimate, highest plausible estimate, best estimate and their degree of confidence that the true values were contained within these upper and lower estimates. We derived estimates of the mean population size of koalas and associated uncertainties for each bioregion and state. Results: On the basis of estimates of mean population sizes for each bioregion and state, we estimated that the total number of koalas for Australia is 329,000 (range 144,000-605,000) with an estimated average decline of 24% over the past three generations and the next three generations. Estimated percentage of loss in Queensland, New South Wales, Victoria and South Australia was 53%, 26%, 14% and 3%, respectively. Main conclusions: It was not necessary to achieve high levels of certainty or consensus among experts before making informed estimates. A quantitative, scientific method for deriving estimates of koala populations and trends was possible, in the absence of empirical data on abundances.

Aim To identify the relative importance of commonly available site and species factors on the probability of extirpating a plant species at the site scale. Location Australia. Methods We reviewed the plant eradication literature and listed the factors commonly cited as influencing eradication success. We then analysed a database of 408 site-scale extirpation attempts, across 17 species eradication programmes, by modelling the time until extirpation to determine the relative influence of these factors on the probability of extirpation, given time. Results The most commonly cited factors influencing eradication success can be classified into two groups as follows: those related to the ‘organisation’, being typically binary variables and amenable to management; and those related to the ‘site/species’, which typically were continuous values and usually beyond the control of the management agency. Detectability period, search distance, monitoring rate, infestation size, propagule longevity, time to reproductive maturity and previous eradication success all influenced the extirpation rate. Conversely, climate suitability, land use and general accessibility (distance to nearest manager) were relatively unimportant. By relating the influential site/species factors to a time-dependent model, managers and policymakers can explicitly estimate the probability of successful extirpation at a site, given a particular time horizon. These estimates can then be aggregated up to the species scale to allow managers to set realistic goals regarding eradication time frames and resource requirements. Main conclusions Our paper illustrates how the probability of extirpation at the site scale can be quantitatively estimated and how these estimates can be used to inform decisions regarding broader species-scale eradication programmes. We expect that the use of such quantitative approaches to select better eradication targets will improve eradication success rates over time.

Aim Risk assessments in applied scientific disciplines have evolved somewhat in isolation, adopting conventions, assumptions and tools from other disciplines almost haphazardly. This editorial provides background for the articles in this special issue, which sample six broad themes in risk assessment in conservation biology and presenting new innovations and applications. Location Global. Methods The articles in the special issue address themes related to species distribution modelling, population viability analysis, threatened species management, biosecurity, uncertainty analysis, cost–benefit analysis and foresight. We sought articles that address new and emerging topics in each of these areas. Results The articles identify new and potentially useful innovations in a variety of areas relevant to conservation biology. Collectively, they paint a picture of risk assessment as an important element in supporting transparent, rational decisions and effective policy. Main conclusions Policy makers and conservation managers aspire to set evidence-based priorities, and technical specialists aim to have their methods used in decision-making. Scientists will succeed if, as the articles in this issue exemplify, they develop a sound understanding of the context of the decisions in which their tools are to be used and shape them accordingly.

AquaticHealth.net is an open-source aquatic biosecurity intelligence gathering and analysis application. The system collects information in much the same way as other similar systems (e.g. HealthMap, BioCaster). However, the information collected undergoes minimal automated analysis, and analysis is largely left to AquaticHealth.net's users. The result is an automated system of intelligence gathering, combined with a manual system of intelligence analysis. This approach relies on a large number of users, and so AquaticHealth.net relies on an open-intelligence analysis method: any user can publish their own analyses for all to see and analyse further. By combining automated data collection and human analysis, AquaticHealth.net will provide fast and accurate forecasts, accompanied with nuanced explanations. These methods can be applied to other areas of biosecurity and disease surveillance.

Aim We aim to explore the capacity of MCDA methods to successfully capture social impacts and integrate stakeholders’ participation into environmental decision applications. We follow a theoretical framework that deconstructs the concept of social impact into two components: human impacts and social change processes. Location Global. Methods We systematically reviewed the literature on MCDA in the Web of Science (ISI) database, finding 119 papers that meet our search criteria. For each paper, we identified the social change processes or human impacts objectives, along with the attributes that measured them. We also recorded the degree of stakeholder participation in each phase of the MCDA stages. Results We found that MCDA practitioners have increasingly integrated social concerns in the analysis of environmental problems, estimating the potential impacts, and developing participative procedures for stakeholders. We identified 252 objectives that represent human impacts or social change processes. Constructed attributes were the most commonly employed (56%), although natural (20%) and proxy (24%) attributes were also relevant. Estimating human impacts or social change processes can involve public participation, but is not a requirement for MCDA: 42% of papers (n = 50) include stakeholder engagement in one or more stages of the decision-making process. We found that stakeholders engage differently across case studies, demonstrating that this process is neither simple nor homogenous. Main conclusions Our review suggests that MCDA methods are appropriate techniques to integrate a wide range of social objectives and stakeholder engagement, supporting well informed and democratic decisions.

Aim Biosecurity responses to incursions aim to achieve pest- or disease-free status as quickly as possible. One of the critical initial response activities involves tracing known movements (trace events) to and from an infected or infested property (IP) that could spread the pest or pathogen. During an incursion response, managers allocate surveillance resources to follow up trace events in order of priority. Prioritizing trace events is difficult and typically subjective. We present a simulation model where several dispersal mechanisms spread a pest between areas. We use model outputs to test different search strategies, using citrus canker (caused by Xanthomonas citri) as a case study. Model scenarios are based on an outbreak of citrus canker that occurred in Queensland in 2004. Location Australia. Methods Model parameters were extracted from published scientific reports and elicited from experts. We used model outputs to assess three search strategies to determine how best to monitor citrus canker spread. Parameters governing disease detectability and host susceptibility were varied in a sensitivity analysis. Results In all simulation scenarios, the ‘adaptive radius’ rule performed best, whereby a circular search area was placed around the IP where the disease outbreak was first detected, with a radius proportional to the estimated number of months the property was infected. Importantly, none of the search rules tested detected all IPs without searching all areas with susceptible hosts in the region. Main conclusions We identify a simple rule of thumb for searching during a citrus canker outbreak that is robust to uncertainty. We cannot generalize the results of this study for tracing other pests or pathogens. The model has created a framework that may be used to explore other contexts and disease dynamics, leading perhaps to more general rules for disease outbreak management.

Aim Decision-making for conservation management often involves evaluating risks in the face of environmental uncertainty. Models support decision-making by (1) synthesizing available knowledge in a systematic, rational and transparent way and (2) providing a platform for exploring and resolving uncertainty about the consequences of management decisions. Despite their benefits, models are still not used in many conservation decision-making contexts. In this article, we provide evidence of common objections to the use of models in environmental decision-making. In response, we present a series of practical solutions for modellers to help improve the effectiveness and relevance of their work in conservation decision-making. Location Global review. Methods We reviewed scientific and grey literature for evidence of common objections to the use of models in conservation decision-making. We present a set of practical solutions based on theory, empirical evidence and best-practice examples to help modellers substantively address these objections. Results We recommend using a structured decision-making framework to guide good modelling practice in decision-making and highlight a variety of modelling techniques that can be used to support the process. We emphasize the importance of participatory decision-making to improve the knowledgebase and social acceptance of decisions and to facilitate better conservation outcomes. Improving communication and building trust are key to successfully engaging participants, and we suggest some practical solutions to help modellers develop these skills.

Aim: Effective decisions for managing invasive species depend on feedback about the progress of eradication efforts. Panetta & Lawes. developed the eradograph, an intuitive graphical tool that summarizes the temporal trajectories of delimitation and extirpation to support decision-making. We correct and extend the tool, which was affected by incompatibilities in the units used to measure these features that made the axes impossible to interpret biologically. Location: Victoria, New South Wales and Queensland, Australia. Methods: Panetta and Lawes' approach represented delimitation with estimates of the changes in the area known to be infested and extirpation with changes in the mean time since the last detection. We retain the original structure but propose different metrics that improve biological interpretability. We illustrate the methods with a hypothetical example and real examples of invasion and treatment of branched broomrape (Orobanche ramosa L.) and the guava rust complex (Puccinia psidii (Winter 1884)) in Australia. Results: These examples illustrate the potential of the tool to guide decisions about the effectiveness of search and control activities. Main conclusions: The eradograph is a graphical data summary tool that provides insight into the progress of eradication. Our correction and extension of the tool make it easier to interpret and provide managers with better decision support. © 2013 John Wiley & Sons Ltd.

Aim Expert knowledge routinely informs ecological research and decision-making. Its reliability is often questioned, but is rarely subject to empirical testing and validation. We investigate the ability of experts to make quantitative predictions of variables for which the answers are known. Location Global. Methods Experts in four ecological subfields were asked to make predictions about the outcomes of scientific studies, in the form of unpublished (in press) journal articles, based on information in the article introduction and methods sections. Estimates from students were elicited for one case study for comparison. For each variable, participants assessed a lower and upper bound, best guess and level of confidence that the observed value will lie within their ascribed interval. Responses were assessed for (1) accuracy: the degree to which predictions corresponded with observed experimental results, (2) informativeness: precision of the uncertainty bounds, and (3) calibration: degree to which the uncertainty bounds contained the truth as often as specified. Results Expert responses were found to be overconfident, specifying 80% confidence intervals that captured the truth only 49-65% of the time. In contrast, student 80% intervals captured the truth 76% of the time, displaying close to perfect calibration. Best estimates from experts were on average more accurate than those from students. The best students outperformed the worst experts. No consistent relationships were observed between performance and years of experience, publication record or self-assessment of expertise. Main conclusions Experts possess valuable knowledge but may require training to communicate this knowledge accurately. Expert status is a poor guide to good performance. In the absence of training and information on past performance, simple averages of expert responses provide a robust counter to individual variation in performance. © 2012 Blackwell Publishing Ltd.

Aim: This study develops methods for efficient surveillance and monitoring systems to address a wide range of problems in biosecurity, ecology and conservation biology. It focuses especially on surveillance systems relevant for management that aims to reduce trade in threatened species and curb the spread of potential pests and diseases. Location: Melbourne, Australia. Methods: This paper develops different approaches to make decisions about the allocation of resources that aim to avoid unacceptable outcomes. The analysis solves for the optimal allocation of surveillance effort in each of two facilities as a function of the arrival rates of invasive species in two facilities (that is, when the arrival rates are known). However, when arrival rates are unknown, it is not possible to solve for this optimum. The analysis also provides a satisficing approach for situations in which arrival rates are unknown, in which a degree of tolerance for deviating from the optimal solution is specified. Results: The study provides simple analytical solutions to these two problems, analogous to results developed earlier in operations research. The analysis is illustrated with an example of the inspection of quarantine facilities for pests and diseases associated with trade. Main conclusions: The best surveillance strategy depends on the choice of an objective function and the attitude of the decision-maker to the robustness of the decision. The example application could be adapted to many other environmental surveillance scenarios. © 2012 Blackwell Publishing Ltd.

Increasing international trade has exacerbated the risks of ecological damage due to invasive pests and diseases. For extreme events such as invasions of damaging exotic species or natural catastrophes, there are no or very few directly relevant data, so expert opinion must be relied on heavily. Expert opinion must be as fully informed and calibrated as possible – by available data, by other experts, and by the reasoned opinions of stakeholders. We survey a number of quantitative and non-quantitative methods that have shown promise for improving extreme risk analysis, particularly for assessing the risks of invasive pests and pathogens associated with international trade. We describe the legally inspired regulatory regime for banks, where these methods have been brought to bear on extreme ‘operational risks’. We argue that an ‘advocacy model’ similar to that used in the Basel II compliance regime for bank operational risks and to a lesser extent in biosecurity import risk analyses is ideal for permitting the diversity of relevant evidence about invasive species to be presented and soundly evaluated. We recommend that the process be enhanced in ways that enable invasion ecology to make more explicit use of the methods found successful in banking.