The mismeasure of conservation

Effectiveness of protected areas in the Caucasus Mountains in preventing rangeland degradation

As land use intensifies globally, it increasingly exerts pressure on protected areas. Despite open, nonforested landscapes comprising up to 40% of protected areas globally, assessments have predominately focused on forests, overlooking the major pressures on rangelands from livestock overgrazing and land conversion. Across the southern Caucasus, a biodiversity hotspot extending over 5 countries, we conducted a broadscale assessment of the extent to which protected areas mitigate land-use pressure on rangelands in them. Using satellite-based indicators of rangeland vegetation greenness from 1988 to 2019, we assessed the effectiveness of 52 protected areas. This period encompassed the collapse of the Soviet Union, economic crises, armed conflicts, and a major expansion of the protected area network. We applied matching statistics combined with fixed-effects panel regressions to quantify the effectiveness of protected areas in curbing degradation as indicated by green vegetation loss. Protected areas were, overall, largely ineffective. Green vegetation loss was higher inside than outside protected areas in most countries, except for Georgia and Turkey. Multiple-use protected areas (IUCN categories IV-VI) were even more ineffective in reducing vegetation loss than strictly protected areas (I & II), highlighting the need for better aligning conservation and development targets in these areas. Mapping >10,000 livestock corrals from satellite images showed that protected areas with a relatively high density of livestock corrals had markedly high green vegetation loss. Ineffectiveness appeared driven by livestock overgrazing. Our key finding was that protected areas did not curb rangeland degradation in the Caucasus. This situation is likely emblematic of many regions worldwide, which highlights the need to incorporate degradation and nonforest ecosystems into effectiveness assessments.

Assessing indirect biodiversity conservation benefits of fisheries closures in the Gulf of St. Lawrence, Canada

Marine biodiversity loss is a pressing global issue, intensified by human activities and climate change. Complementary to marine protected areas (MPAs), Other Effective Area-Based Conservation Measures (OECMs) have emerged as a key tool to mitigate this loss by providing long-term biodiversity protection. However, while OECMs primarily target specific taxa, they can also offer indirect biodiversity conservation benefits (BCBs) to a wider range of taxa. In this study, we assess the indirect BCBs of eleven OECMs in the Gulf of St. Lawrence, focusing on their role in supporting the life-history processes of commercially important species such as Atlantic halibut, Greenland halibut, and redfish. We apply an integrated assessment that combines knowledge and data previously unconnected to provide information to support OECM management. Our analysis reveals that eight of the eleven OECMs overlap with potential spawning habitats for these species, suggesting important life-history benefits. However, projected climate-driven changes in bottom temperature, oxygen concentration, and pH levels pose a threat to these habitats, potentially undermining the long-term effectiveness of OECMs. These findings underscore the need for adaptive management strategies that incorporate climate-informed ecosystem indicators and broaden the conservation focus beyond economically important species. Such approaches are crucial to ensuring that OECMs continue to provide both direct and indirect BCBs in the face of accelerating climate change, thereby contributing to global marine biodiversity conservation efforts.

Considering Multiecosystem Trade-Offs Is Critical When Leveraging Systematic Conservation Planning for Restoration

Conservationists are increasingly leveraging systematic conservation planning (SCP) to inform restoration actions that enhance biodiversity. However, restoration frequently drives ecological transformations at local scales, potentially resulting in trade-offs among wildlife species and communities. The Conservation Interactions Principle (CIP), coined more than 15 years ago, cautions SCP practitioners regarding the importance of jointly and fully evaluating conservation outcomes across the landscape over long timeframes. However, SCP efforts that guide landscape restoration have inadequately addressed the CIP by failing to tabulate the full value of the current ecological state. The increased application of SCP to inform restoration, reliance on increasingly small areas to sustain at-risk species and ecological communities, ineffective considerations for the changing climate, and increasing numbers of at-risk species, are collectively intensifying the need to consider unintended consequences when prioritizing sites for restoration. Improper incorporation of the CIP in SCP may result in inefficient use of conservation resources through opportunity costs and/or conservation actions that counteract one another. We suggest SCP practitioners can avoid these consequences through a more detailed accounting of the current ecological benefits to better address the CIP when conducting restoration planning. Specifically, forming interdisciplinary teams with expertise in the current and desired ecosystem states at candidate conservation sites; improving data availability; modeling and computational advancements; and applying structured decision-making approaches can all improve the integration of the CIP in SCP efforts. Improved trade-off assessment, spanning multiple ecosystems or states, can facilitate efficient, proactive, and coordinated SCP applications across space and time. In doing so, SCP can effectively guide the siting of restoration actions capable of promoting the full suite of biodiversity in a region.

Limits to the ability of carbon farming projects to deliver benefits for threatened species

Australia has proposed a legislated market for biodiversity based on an existing carbon credits scheme which generates Australian carbon credit units (ACCU) from land-based projects. This provides a unique opportunity to assess the potential for markets to benefit biodiversity. We assessed the extent to which projects under the ACCU scheme overlap potential threatened species habitat, compared that to overlap afforded by protected areas, and compared the ability of different project types to deliver potential benefits to species most impacted by habitat loss. Projects are primarily located in low-cost, marginal arid lands, a pattern that reflects that of the protected area estate. Projects are smaller and fewer in number in more productive lands close to human populations. These lands also overlap most threatened species habitat, hence those species most in need of habitat restoration are the least likely to have their habitat restored under the ACCU scheme. Projects, however, do overlap the geographic range of 32% of the 1,660 threatened species assessed, including for 275 species with <17% of their range in protected areas. Biodiversity markets must incentivize actions in areas of high biodiversity value underpinned by regulations that align with national priorities for biodiversity conservation.

A standard lexicon of terms for area-based conservation version 1.0

Target 3 in the Kunming-Montreal Global Biodiversity Framework (GBF) calls for protecting at least 30% of the world's lands and waters in area-based conservation approaches by 2030. This ambitious 30×30 target has spurred great interest among policy makers, practitioners, and researchers in defining and measuring the effectiveness of these types of approaches. But along with this broad interest, there has also been a proliferation of terms and their accompanying abbreviations used to describe different types of conservation areas and their governance, planning, management, and monitoring. The lack of standard terms is hindering the use and assessment of area-based approaches to conserve the world's biodiversity. It is difficult to track progress toward GBF Target 3 or to share learning with other practitioners if different groups of people are using different words to describe the same concept or similar words to talk about different concepts. To address this problem, the International Union for Conservation of Nature's World Commission on Protected Areas commissioned a task force to review existing terms and recommend a standard English-language lexicon for this field based on key criteria. The results were definitions of 37 terms across 6 categories, including types of protected and additional conservation areas (e.g., protected area, additional conservation area), sets of these areas (protected area network, protected area system), their governance and management (governance, rightsholders), assessment (effectiveness, equitability), spatial planning (key biodiversity area), and action planning (value, outcome, objective). Our standard lexicon can provide a common language for people who want to use it and a shared reference point that can be used to translate various terms used by different groups. The common understanding provided by the lexicon can serve as a foundation for collaborative efforts to improve the policies, implementation, assessments, research, and learning about this important set of conservation approaches.

Aquatic connectivity: challenges and solutions in a changing climate

The challenge of managing aquatic connectivity in a changing climate is exacerbated in the presence of additional anthropogenic stressors, social factors, and economic drivers. Here we discuss these issues in the context of structural and functional connectivity for aquatic biodiversity, specifically fish, in both the freshwater and marine realms. We posit that adaptive management strategies that consider shifting baselines and the socio-ecological implications of climate change will be required to achieve management objectives. The role of renewable energy expansion, particularly hydropower, is critically examined for its impact on connectivity. We advocate for strategic spatial planning that incorporates nature-positive solutions, ensuring climate mitigation efforts are harmonized with biodiversity conservation. We underscore the urgency of integrating robust scientific modelling with stakeholder values to define clear, adaptive management objectives. Finally, we call for innovative monitoring and predictive decision-making tools to navigate the uncertainties inherent in a changing climate, with the goal of ensuring the resilience and sustainability of aquatic ecosystems.

Disentangling linkages between satellite-derived indicators of forest structure and productivity for ecosystem monitoring

The essential biodiversity variables (EBV) framework has been proposed as a monitoring system of standardized, comparable variables that represents a minimum set of biological information to monitor biodiversity change at large spatial extents. Six classes of EBVs (genetic composition, species populations, species traits, community composition, ecosystem structure and ecosystem function) are defined, a number of which are ideally suited to observation and monitoring by remote sensing systems. We used moderate-resolution remotely sensed indicators representing two ecosystem-level EBV classes (ecosystem structure and function) to assess their complementarity and redundancy across a range of ecosystems encompassing significant environmental gradients. Redundancy analyses found that remote sensing indicators of forest structure were not strongly related to indicators of ecosystem productivity (represented by the Dynamic Habitat Indices; DHIs), with the structural information only explaining 15.7% of the variation in the DHIs. Complex metrics of forest structure, such as aboveground biomass, did not contribute additional information over simpler height-based attributes that can be directly estimated with light detection and ranging (LIDAR) observations. With respect to ecosystem conditions, we found that forest types and ecosystems dominated by coniferous trees had less redundancy between the remote sensing indicators when compared to broadleaf or mixed forest types. Likewise, higher productivity environments exhibited the least redundancy between indicators, in contrast to more environmentally stressed regions. We suggest that biodiversity researchers continue to exploit multiple dimensions of remote sensing data given the complementary information they provide on structure and function focused EBVs, which makes them jointly suitable for monitoring forest ecosystems.

Systematic nature positive markets

Environmental markets are a rapidly emerging tool to mobilize private funding to incentivize landholders to undertake more sustainable land management. How units of biodiversity in these markets are measured and subsequently traded creates key challenges ecologically and economically because it determines whether environmental markets can deliver net gains in biodiversity and efficiently lower the costs of conservation. We developed and tested a metric for such markets based on the well-established principle of irreplaceability from systematic conservation planning. Irreplaceability as a metric avoids the limitations of like-for-like trading and allows one to capture the multidimensional nature of ecosystems (e.g., habitats, species, ecosystem functioning) and simultaneously achieve cost-effective, land-manager-led investments in conservation. Using an integrated ecological modeling approach, we tested whether using irreplaceability as a metric is more ecologically and economically beneficial than the simpler biodiversity offset metrics typically used in net gain and no-net-loss policies. Using irreplaceability ensured no net loss, or even net gain, of biodiversity depending on the targets chosen. Other metrics did not provide the same assurances and, depending on the flexibility with which biodiversity targets can be achieved, and how they overlap with development pressure, were less efficient. Irreplaceability reduced the costs of offsetting to developers and the costs of ecological restoration to society. Integrating economic data and systematic conservation planning approaches would therefore assure land managers they were being fairly rewarded for the opportunity costs of conservation and transparently incentivize the most ecologically and economically efficient investments in nature recovery.

An assessment of the state of conservation planning in Europe

Expanding and managing current habitat and species protection measures is at the heart of the European biodiversity strategy. A structured approach is needed to gain insights into such issues is systematic conservation planning, which uses techniques from decision theory to identify places and actions that contribute most effectively to policy objectives given a set of constraints. Yet culturally and historically determined European landscapes make the implementation of any conservation plans challenging, requiring an analysis of synergies and trade-offs before implementation. In this work, we review the scientific literature for evidence of previous conservation planning approaches, highlighting recent advances and success stories. We find that the conceptual characteristics of European conservation planning studies likely reduced their potential in contributing to better-informed decisions. We outline pathways towards improving the uptake of decision theory and multi-criteria conservation planning at various scales, particularly highlighting the need for (a) open data and intuitive tools, (b) the integration of biodiversity-focused conservation planning with multiple objectives, (c) accounting of dynamic ecological processes and functions, and (d) better facilitation of entry-points and co-design practices of conservation planning scenarios with stakeholders. By adopting and improving these practices, European conservation planning might become more actionable and adaptable towards implementable policy outcomes. This article is part of the theme issue 'Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere'.

Systematic review of the uncertainty of coral reef futures under climate change

Climate change impact syntheses, such as those by the Intergovernmental Panel on Climate Change, consistently assert that limiting global warming to 1.5 °C is unlikely to safeguard most of the world's coral reefs. This prognosis is primarily based on a small subset of available models that apply similar 'excess heat' threshold methodologies. Our systematic review of 79 articles projecting coral reef responses to climate change revealed five main methods. 'Excess heat' models constituted one third (32%) of all studies but attracted a disproportionate share (68%) of citations in the field. Most methods relied on deterministic cause-and-effect rules rather than probabilistic relationships, impeding the field's ability to estimate uncertainty. To synthesize the available projections, we aimed to identify models with comparable outputs. However, divergent choices in model outputs and scenarios limited the analysis to a fraction of available studies. We found substantial discrepancies in the projected impacts, indicating that the subset of articles serving as a basis for climate change syntheses may project more severe consequences than other studies and methodologies. Drawing on insights from other fields, we propose methods to incorporate uncertainty into deterministic modeling approaches and propose a multi-model ensemble approach to generating probabilistic projections for coral reef futures.

Conservation planning for retention, not just protection

Most protected area (PA) planning aims to improve biota representation within the PA system, but this does not necessarily achieve the best outcomes for biota retention across regions when we also consider habitat loss in areas outside the PA system. Here, we assess the implications that different PA expansion strategies can have on the retention of species habitat across an entire region. Using retention of forest habitat for Colombia's 550 forest-dependent bird species as our outcome variable, we found that when a minimum of 30% of each species' habitat was included in the PA system, a pattern of PA expansion targeting areas at highest deforestation risk (risk-prevention) led to the retention, on average, of 7.2% more forest habitat per species by 2050 than did a pattern that targeted areas at lowest risk (risk-avoidance). The risk-prevention approach cost more per km2 of land conserved, but it was more cost-effective in retaining habitat in the landscape (50%-69% lower cost per km2 of avoided deforestation). To have the same effectiveness preventing habitat loss in Colombia, the risk-avoidance approach would require more than twice as much protected area, costing three times more in the process. Protected area expansion should focus on the contributions of PAs to outcomes not only within PA systems themselves, but across entire regions.

Effects of management objectives and rules on marine conservation outcomes

Understanding the relative effectiveness and enabling conditions of different area-based management tools is essential for supporting efforts that achieve positive biodiversity outcomes as area-based conservation coverage increases to meet newly set international targets. We used data from a coastal social-ecological monitoring program in 6 Indo-Pacific countries to analyze whether social, ecological, and economic objectives and specific management rules (temporal closures, fishing gear-specific, species-specific restrictions) were associated with coral reef fish biomass above sustainable yield levels across different types of area-based management tools (i.e., comparing those designated as marine protected areas [MPAs] with other types of area-based management). All categories of objectives, multiple combinations of rules, and all types of area-based management had some sites that were able to sustain high levels of reef fish biomass-a key measure for coral reef functioning-compared with reference sites with no area-based management. Yet, the same management types also had sites with low biomass. As governments advance their commitments to the Kunming-Montreal Global Biodiversity Framework and the target to conserve 30% of the planet's land and oceans by 2030, we found that although different types of management can be effective, most of the managed areas in our study regions did not meet criteria for effectiveness. These findings underscore the importance of strong management and governance of managed areas and the need to measure the ecological impact of area-based management rather than counting areas because of their designation.

Quantifying population-level conservation impacts for a perpetual conservation program on private land

Area-based targets, such as percentages of regions protected, are popular metrics of success in the protection of nature. While easily quantified, these targets can be uninformative about the effectiveness of conservation interventions and should be complemented by program impact evaluations. However, most impact evaluations have examined the effect of protected areas on deforestation. Studies that have extended these evaluations to more dynamic systems or different outcomes are less common, largely due to data availability. In these cases, simulations might prove to be a valuable tool for gaining an understanding of the potential range of program effect sizes. Here, we employ simulations of wetland drainage to estimate the impact of the United States Fish and Wildlife Service Small Wetlands Acquisition Program (SWAP) across a ten-year period in terms of wetland area, and breeding waterfowl and brood abundance in the Prairie Pothole Region of North Dakota, South Dakota, and Montana. Using our simulation results, we estimate a plausible range of program impact for the SWAP as an avoided loss of between 0.00% and 0.02% of the carrying capacity for broods and breeding waterfowl from 2008-2017. Despite the low programmatic impact that these results suggest, the perpetual nature of SWAP governance provides promising potential for a higher cumulative conservation impact in the long term if future wetland drainage occurs.

Protected areas slow declines unevenly across the tetrapod tree of life

Protected areas (PAs) are the primary strategy for slowing terrestrial biodiversity loss. Although expansion of PA coverage is prioritized under the Convention on Biological Diversity, it remains unknown whether PAs mitigate declines across the tetrapod tree of life and to what extent land cover and climate change modify PA effectiveness1,2. Here we analysed rates of change in abundance of 2,239 terrestrial vertebrate populations across the globe. On average, vertebrate populations declined five times more slowly within PAs (-0.4% per year) than at similar sites lacking protection (-1.8% per year). The mitigating effects of PAs varied both within and across vertebrate classes, with amphibians and birds experiencing the greatest benefits. The benefits of PAs were lower for amphibians in areas with converted land cover and lower for reptiles in areas with rapid climate warming. By contrast, the mitigating impacts of PAs were consistently augmented by effective national governance. This study provides evidence for the effectiveness of PAs as a strategy for slowing tetrapod declines. However, optimizing the growing PA network requires targeted protection of sensitive clades and mitigation of threats beyond PA boundaries. Provided the conditions of targeted protection, adequate governance and well-managed landscapes are met, PAs can serve a critical role in safeguarding tetrapod biodiversity.

The Marine Spatial Planning Index: a tool to guide and assess marine spatial planning

Marine spatial planning (MSP) has the potential to balance demands for ocean space with environmental protection and is increasingly considered crucial for achieving global ocean goals. In theory, MSP should adhere to six principles, being: (1) ecosystem-based, (2) integrated, (3) place-based, (4) adaptive, (5) strategic, and (6) participatory. Despite nearly two decades of practice, MSP continues to face critical challenges to fully realize these principles, hindering its ability to deliver positive outcomes for people and nature. Here, we present the MSP Index, a tool for assessing progress in MSP processes based on MSP principles that can guide practitioners in operationalizing these principles. Using qualitative analysis of fundamental MSP guides, complemented with a literature review, we identified key features of MSP principles and developed these features into a scoring guide that assesses progress relative to each principle. We trialed and validated the MSP Index on six case studies from distinct regions. We found that the MSP Index allows for high-level comparison across diverse marine spatial plans, highlighting the extent to which MSP principles have permeated practice. Our results reveal successes, especially for the place-based principle, and failures to fully adhere to the adaptive and participatory principles of MSP. The Index serves as a guidance tool that would be best employed by practitioners and can inform science on the evolution of MSP. It is a user-friendly tool that translates MSP principles into practice, allowing for assessment of individual initiatives and comparison of diverse initiatives across ocean regions and nations.

Madagascar’s extraordinary biodiversity: Threats and opportunities

Madagascar’s unique biota is heavily affected by human activity and is under intense threat. Here, we review the current state of knowledge on the conservation status of Madagascar’s terrestrial and freshwater biodiversity by presenting data and analyses on documented and predicted species-level conservation statuses, the most prevalent and relevant threats, ex situ collections and programs, and the coverage and comprehensiveness of protected areas. The existing terrestrial protected area network in Madagascar covers 10.4% of its land area and includes at least part of the range of the majority of described native species of vertebrates with known distributions (97.1% of freshwater fishes, amphibians, reptiles, birds, and mammals combined) and plants (67.7%). The overall figures are higher for threatened species (97.7% of threatened vertebrates and 79.6% of threatened plants occurring within at least one protected area). International Union for Conservation of Nature (IUCN) Red List assessments and Bayesian neural network analyses for plants identify overexploitation of biological resources and unsustainable agriculture as the most prominent threats to biodiversity. We highlight five opportunities for action at multiple levels to ensure that conservation and ecological restoration objectives, programs, and activities take account of complex underlying and interacting factors and produce tangible benefits for the biodiversity and people of Madagascar.

Demystifying ecological connectivity for actionable spatial conservation planning

Connectivity underpins the persistence of life; it needs to inform biodiversity conservation decisions. Yet, when prioritising conservation areas and developing actions, connectivity is not being operationalised in spatial planning. The challenge is the translation of flows associated with connectivity into conservation objectives that lead to actions. Connectivity is nebulous, it can be abstract and mean different things to different people, making it difficult to include in conservation problems. Here, we show how connectivity can be included in mathematically defining conservation planning objectives. We provide a path forward for linking connectivity to high-level conservation goals, such as increasing species' persistence. We propose ways to design spatial management areas that gain biodiversity benefit from connectivity.

Defining performance thresholds for effective management of biodiversity within protected areas

Performance thresholds are an important tool for determining successful conservation outcomes. They provide an objective means of defining good ecological condition and have been endorsed as an essential part of best practice in protected area (PA) management within the International Union for the Conservation of Nature Green List of Protected and Conserved Areas Standard. With a growing number of PAs attaining Green List status globally, thresholds developed by PAs on the Green List present an excellent resource with which to identify the attributes of well-defined performance thresholds. We examined 349 thresholds associated with PAs on the Green List to determine whether they were specific and measurable (i.e., factors recognized as essential for setting well-defined targets). We assessed whether thresholds were defined quantitatively and whether definitions included ambiguous terms (e.g., stable numbers). We identified six different ways thresholds were expressed and found that many thresholds were expressed as management objectives, rather than ecological condition thresholds, although this trend improved over time. Approximately one-half of the performance thresholds lacked the necessary specificity to delineate successful outcomes. Our results enabled us to develop a checklist of information required to set robust performance thresholds. Recommendations include that thresholds should be quantitatively defined, including quantitative estimates of the limits of acceptable change (LAC) around the target condition. To ensure transparency, a rationale and associated evidence should be provided to support the threshold and the LAC. When accompanied by a rationale and quantitative estimate of the current condition of the value, unambiguously defined thresholds with a quantitative LAC provide an objective means of demonstrating that successful conservation outcomes have been achieved. These recommendations will help conservation managers apply the Green List Standard and improve the measurement of conservation outcomes more broadly.

Linking small-scale fisheries co-management to U.N. Sustainable Development Goals

Small-scale fisheries account for 90% of global fishers and 40% of the global catch. Effectively managing small-scale fisheries is, therefore, crucial to progressing the United Nations Sustainable Development Goals (SDGs). Co-management and community-based fisheries management are widely considered the most appropriate forms of governance for many small-scale fisheries. We outlined relationships between small-scale fisheries co-management and attainment of the SDGs, including evidence for impacts and gaps in dominant logic. We identified 11 targets across five SDGs to which small-scale fisheries co-management (including community-based fisheries management) can contribute; the theory of change by which these contributions could be achieved; and the strength of evidence for progress toward SDG targets related to various co-management strategies. Our theory of change links the 11 SDG targets by qualifying that progress toward some targets is contingent on others being achieved first. We then reviewed 58 case studies of co-management impacts from the Pacific Islands--a region rich in local marine governance--to evaluate evidence of where, to what degree, and with how much certainty different co-management strategies conferred positive impacts to each SDG target. These strategies included access restrictions, permanent area closures, periodic closures, and gear and species restrictions. Although many studies provide evidence linking multiple co-management strategies to improvements in resource status (SDG 14.4), there was limited evidence of follow-on effects, such as improvements in catch (SDG 2.3, 2.4), livelihoods (SDG 1.2), consumption (SDG 2.1), and nutrition (SDG 2.2). Our findings suggest that leaps of logic and assumptions are prevalent in co-management planning and evaluation. Hence, when evaluating co-management impacts against the SDGs, consideration of ultimate goals is required, otherwise, there is a risk of shortfalls between aspirations and impact.

Analysis of differences and commonalities in wildlife hunting across the Africa-Europe South-North gradient

Hunting and its impacts on wildlife are typically studied regionally, with a particular focus on the Global South. Hunting can, however, also undermine rewilding efforts or threaten wildlife in the Global North. Little is known about how hunting manifests under varying socioeconomic and ecological contexts across the Global South and North. Herein, we examined differences and commonalities in hunting characteristics across an exemplary Global South-North gradient approximated by the Human Development Index (HDI) using face-to-face interviews with 114 protected area (PA) managers in 25 African and European countries. Generally, we observed that hunting ranges from the illegal, economically motivated, and unsustainable hunting of herbivores in the South to the legal, socially and ecologically motivated hunting of ungulates within parks and the illegal hunting of mainly predators outside parks in the North. Commonalities across this Africa-Europe South-North gradient included increased conflict-related killings in human-dominated landscapes and decreased illegal hunting with beneficial community conditions, such as mutual trust resulting from community involvement in PA management. Nevertheless, local conditions cannot outweigh the strong effect of the HDI on unsustainable hunting. Our findings highlight regional challenges that require collaborative, integrative efforts in wildlife conservation across actors, while identified commonalities may outline universal mechanisms for achieving this goal.

Hunting and its impacts on wildlife are typically studied regionally, with a particular focus on the Global South. An assessment across a contrasting South-North gradient reveals differences in the ecological, social, and economic dimensions of hunting, but also identifies commonalities that point to general ways to reduce unsustainable hunting.

Towards evidence-based conservation of subterranean ecosystems

Subterranean ecosystems are among the most widespread environments on Earth, yet we still have poor knowledge of their biodiversity. To raise awareness of subterranean ecosystems, the essential services they provide, and their unique conservation challenges, 2021 and 2022 were designated International Years of Caves and Karst. As these ecosystems have traditionally been overlooked in global conservation agendas and multilateral agreements, a quantitative assessment of solution-based approaches to safeguard subterranean biota and associated habitats is timely. This assessment allows researchers and practitioners to understand the progress made and research needs in subterranean ecology and management. We conducted a systematic review of peer-reviewed and grey literature focused on subterranean ecosystems globally (terrestrial, freshwater, and saltwater systems), to quantify the available evidence-base for the effectiveness of conservation interventions. We selected 708 publications from the years 1964 to 2021 that discussed, recommended, or implemented 1,954 conservation interventions in subterranean ecosystems. We noted a steep increase in the number of studies from the 2000s while, surprisingly, the proportion of studies quantifying the impact of conservation interventions has steadily and significantly decreased in recent years. The effectiveness of 31% of conservation interventions has been tested statistically. We further highlight that 64% of the reported research occurred in the Palearctic and Nearctic biogeographic regions. Assessments of the effectiveness of conservation interventions were heavily biased towards indirect measures (monitoring and risk assessment), a limited sample of organisms (mostly arthropods and bats), and more accessible systems (terrestrial caves). Our results indicate that most conservation science in the field of subterranean biology does not apply a rigorous quantitative approach, resulting in sparse evidence for the effectiveness of interventions. This raises the important question of how to make conservation efforts more feasible to implement, cost-effective, and long-lasting. Although there is no single remedy, we propose a suite of potential solutions to focus our efforts better towards increasing statistical testing and stress the importance of standardising study reporting to facilitate meta-analytical exercises. We also provide a database summarising the available literature, which will help to build quantitative knowledge about interventions likely to yield the greatest impacts depending upon the subterranean species and habitats of interest. We view this as a starting point to shift away from the widespread tendency of recommending conservation interventions based on anecdotal and expert-based information rather than scientific evidence, without quantitatively testing their effectiveness.

How percentage-protected targets can support positive biodiversity outcomes

Global targets for the percentage area of land protected, such as 30% by 2030, have gained increasing prominence, but both their scientific basis and likely effectiveness have been questioned. As with emissions-reduction targets based on desired climate outcomes, percentage-protected targets combine values and science by estimating the area over which conservation actions are required to help achieve desired biodiversity outcomes. Protected areas are essential for achieving many biodiversity targets, in part because many species are highly sensitive to human-associated disturbance. However, because the contribution of protected areas to biodiversity outcomes is contingent on their location, management, governance, threats, and what occurs across the broader landscape matrix, global percentage-protected targets are unavoidably empirical generalizations of ecological patterns and processes across diverse geographies. Percentage-protected targets are insufficient in isolation but can complement other actions and contribute to biodiversity outcomes within a framework that balances accuracy and pragmatism in a global context characterized by imperfect biodiversity data. Ideally, percentage-protected targets serve as anchors that strengthen comprehensive national biodiversity strategies by communicating the level of ambition necessary to reverse current trends of biodiversity loss. If such targets are to fulfill this role within the complex societal process by which both values and science impel conservation actions, conservation scientists must clearly communicate the nature of the evidence base supporting percentage-protected targets and how protected areas can function within a broader landscape managed for sustainable coexistence between people and nature. A new paradigm for protected and conserved areas recognizes that national coordination, incentives, and monitoring should support rather than undermine diverse locally led conservation initiatives. However, the definition of a conserved area must retain a strong focus on biodiversity to remain consistent with the evidence base from which percentage-protected targets were originally derived.

High exposure of global tree diversity to human pressure

Safeguarding Earth's tree diversity is a conservation priority due to the importance of trees for biodiversity and ecosystem functions and services such as carbon sequestration. Here, we improve the foundation for effective conservation of global tree diversity by analyzing a recently developed database of tree species covering 46,752 species. We quantify range protection and anthropogenic pressures for each species and develop conservation priorities across taxonomic, phylogenetic, and functional diversity dimensions. We also assess the effectiveness of several influential proposed conservation prioritization frameworks to protect the top 17% and top 50% of tree priority areas. We find that an average of 50.2% of a tree species' range occurs in 110-km grid cells without any protected areas (PAs), with 6,377 small-range tree species fully unprotected, and that 83% of tree species experience nonnegligible human pressure across their range on average. Protecting high-priority areas for the top 17% and 50% priority thresholds would increase the average protected proportion of each tree species' range to 65.5% and 82.6%, respectively, leaving many fewer species (2,151 and 2,010) completely unprotected. The priority areas identified for trees match well to the Global 200 Ecoregions framework, revealing that priority areas for trees would in large part also optimize protection for terrestrial biodiversity overall. Based on range estimates for >46,000 tree species, our findings show that a large proportion of tree species receive limited protection by current PAs and are under substantial human pressure. Improved protection of biodiversity overall would also strongly benefit global tree diversity.

Habitat Protection Indexes - new monitoring measures for the conservation of coastal and marine habitats

A worldwide call to implement habitat protection aims to halt biodiversity loss. We constructed an open-source, standardized, and reproducible workflow that calculates two indexes to monitor the extent of coastal and marine habitats within protected areas and other effective area-based conservation measures. The Local Proportion of Habitats Protected Index (LPHPI) pinpoints the jurisdictions with the greatest opportunity to expand their protected or conserved areas, while the Global Proportion of Habitats Protected Index (GPHPI) showcases which jurisdictions contribute the most area to the protection of these habitats globally. We also evaluated which jurisdictions have the highest opportunity to contribute globally to protecting habitats by meeting a target of 30% coverage. We found that Areas Beyond National Jurisdiction (ABNJ) have the greatest potential to do so. Our workflow can also be easily extended to terrestrial and freshwater habitats. These indexes are helpful to monitor aspects of the Sustainable Development Goal 14 and the emerging post-2020 global biodiversity framework, to understand the current status of international cooperation on coastal and marine habitats conservation.