There has been much recent interest in the concept of rewilding as a tool for nature conservation, but also confusion over the idea, which has in turn limited its utility. We outline a unified definition and a series of ten guiding principles for rewilding, drawing on a global advisory group of rewilding experts. These were developed through a survey of 59 rewilding pioneers, a summary of key organisations’ rewilding visions, and academic/practitioner workshops involving over 100 participants from around the world. The resulting principles are intended to clarify the concept of rewilding and to improve its effectiveness as a tool to achieve global conservation targets including actions of the UN Decade on Ecosystem Restoration and post‐2020 Global Biodiversity Framework. As such we note the potential contribution of other related conservation approaches such as the IUCN CEM NbS programme. The guiding principles developed here state implicitly that rewilding sits upon a continuum of scale, connectivity, and level of human influence, and aims to restore ecosystem structure and functions to achieve a self‐sustaining autonomous nature. We suggest that differences in rewilding perspectives lie largely in the extent to which this is seen as achievable, and ultimately, in those interventions which are necessary, feasible or acceptable. An understanding of the contextual setting of rewilding projects is often the key to success, and careful site‐specific interpretations will be most successful at achieving the aims of rewilding. Article impact statement: Rewilding is on a continuum of scale, connectivity, and human influence and aims to restore ecosystems to achieve self‐sustaining nature. This article is protected by copyright. All rights reserved

Extinction rates are expected to increase during the Anthropocene. Current extinction rates of plants and many animals remain unknown. This study represents the first effort to quantify extinctions among the vascular flora of North America north of Mexico since European settlement. We compiled data on apparently extinct species by querying plant conservation databases, searching literature, and vetting the resulting list with botanical experts. Because taxonomic opinion varies widely, we developed an Index of Taxonomic Uncertainty (ITU). The ITU ranges from A to F, with A indicating unanimous taxonomic recognition and F indicating taxonomic recognition by only a single author. The ITU allowed us to rigorously evaluate extinction rates. Our data suggest 65 taxa (51 species and 14 infraspecific taxa) representing 33 families and 49 genera of vascular plants have become extinct in our study area since European settlement. Seven of these taxa exist in cultivation but are extinct in the wild. We found most extinctions in western North America, but that disparity may reflect the timing of botanical exploration relative to settlement. Sixty‐four percent of extinct plants were single‐site endemics, and many occurred outside recognized biodiversity hotspots. Given the paucity of plant surveys in many areas of North America, particularly prior to European settlement, the actual extinction rate of vascular plants is undoubtedly much higher than indicated here. Article Impact Statement: The number of presumed extinct plants from the continental United States and Canada is much greater than previously recognized. This article is protected by copyright. All rights reserved

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.

First posted May 20, 2021 Director, Lower Mississippi-Gulf Water Science Center U.S. Geological Survey 640 Grassmere Park Drive Nashville, TN 37211 The unglaciated southeastern United States is a biodiversity hotspot, with a disproportionate amount of this biodiversity concentrated in grasslands. Like most hotspots, the Southeast is also threatened by human activities, with the total reduction of southeastern grasslands estimated as 90 percent (upwards to 100 percent for some types) and with many threats escalating today. This report summarizes the results of a multistakeholder workshop organized by the Southeastern Grasslands Initiative and the U.S. Geological Survey, held in January 2020 to provide a scientific needs assessment to help inform the Species Status Assessment (SSA) process under the U.S. Endangered Species Act, with a focus on grassland species and communities of conservation concern in the southeastern United States. This report reviews the ecology of southeastern grasslands, including influences on their origin, maintenance, and high species richness and endemism; presents findings from the workshop; and discusses science questions, hypotheses, and possibilities for future research projects to help fill key knowledge gaps. Participants in the January 2020 workshop, representing diverse expertise in various topics in southeastern grassland ecology, were tasked with identifying major threats to grassland species in the Southeast as well as potential ways to make the SSA process more efficient and effective. An underlying assumption and starting place for workshop discussion was that an ecosystem-based approach to the SSA process is more cost-efficient than a species-by-species approach, in large part because many species with similar biological requirements can be addressed by the same actions. Nevertheless, one partner in this effort, the U.S. Fish and Wildlife Service, does require specific attention be given to taxa that have been petitioned for Federal listing, though as often as possible these taxa are considered alongside a larger group of priority taxa with an ecosystem approach. For group discussions, workshop participants followed a modified “World Café” method, a structured conversational approach for knowledge sharing. Group discussions focused on five categories of threats to grassland communities and species: (1) habitat loss, fragmentation, and disruption of functional population connectivity; (2) climate change, especially changes in temperature and precipitation, including intensity and seasonality, and impacts on soil moisture, groundwater levels, and other ecosystem parameters; (3) changes to disturbance regimes, as influenced by climate and land-use change, extinctions, and human attitudes and behaviors; (4) invasive species (not limited to nonnative species); and (5) localized or subregional impacts such as sea-level rise. In addition to group discussions, workshop participants—as well as other grassland experts who were unable to attend the workshop—completed a preworkshop survey concerning challenges and opportunities for grassland conservation. Findings reported here under each of these topics represent ideas, problems, hypotheses, and questions identified by a diverse community of grassland managers and researchers which may be addressed by future research and monitoring in southeastern grassland ecosystems to help guide science-based conservation of grassland-dependent species.

Many species listed under the US Endangered Species Act (ESA) face continuing threats and will require intervention to address those threats for decades. These species, which have been termed conservation‐reliant, pose a challenge to the ESA's mandate for recovery of self‐sustaining populations. Most references to conservation‐reliant species by federal agencies involve the restoration of population connectivity. However, the diverse threats to connectivity faced by different species have contrasting implications in the context of the ESA's mandate. For species facing long‐term threats from invasive species or climate change, restoration of natural dispersal may not be technically feasible in the foreseeable future. For other species, restoration of natural dispersal is feasible, but carries economic and political cost. Federal agencies have used a broad definition of conservation reliance to justify delisting of species in the latter group even if they remain dependent on artificial translocation. Distinguishing the two groups better informs policy by distinguishing the technical challenges posed by novel ecological stressors from normative questions such as the price society is willing to pay to protect biodiversity, and the degree to which we should grow accustomed to direct human intervention in species’ life cycles as a component of conservation in the Anthropocene Epoch.

Despite its successes, the U.S. Endangered Species Act (ESA) has proven challenging to implement due to funding limitations, workload backlog, and other problems. As threats to species survival intensify and as more species come under threat, the need for the ESA and similar conservation laws and policies in other countries to function efficiently has grown. Attempts by the U.S. Fish and Wildlife Service (USFWS) to streamline ESA decisions include multispecies recovery plans and habitat conservation plans. We address species status assessment (SSA), a USFWS process to inform ESA decisions from listing to recovery, within the context of multispecies and ecosystem planning. Although existing SSAs have a single‐species focus, ecosystem‐based research can efficiently inform multiple SSAs within a region and provide a foundation for transition to multispecies SSAs in the future. We considered at‐risk grassland species and ecosystems within the southeastern United States, where a disproportionate number of rare and endemic species are associated with grasslands. To initiate our ecosystem‐based approach, we used a combined literature‐based and structured World Café workshop format to identify science needs for SSAs. Discussions concentrated on 5 categories of threats to grassland species and ecosystems, consistent with recommendations to make shared threats a focus of planning under the ESA: (1) habitat loss, fragmentation, and disruption of functional connectivity; (2) climate change; (3) altered disturbance regimes; (4) invasive species; and (5) localized impacts. For each threat, workshop participants identified science and information needs, including database availability, research priorities, and modeling and mapping needs. Grouping species by habitat and shared threats can make the SSA process and other planning processes for conservation of at‐risk species worldwide more efficient and useful. We found a combination of literature review and structured discussion effective for identifying the scientific information and analysis needed to support the development of multiple SSAs. Article impact statement : Species status assessments can be improved by an ecosystem‐based approach that groups imperiled species by shared habitats and threats.