Introduction: Growth in understanding of ecological restoration necessitates updated guidance for effective, equitable, and outcome-oriented restoration across terrestrial, inland water, and coastal and marine ecosystems. The third edition of the Society for Ecological Restoration (SER) International Principles and Standards for the Practice of Ecological Restoration provides an expanded, evidence-based framework for ecological restoration aligned with the United Nations Decade on Ecosystem Restoration and other global frameworks. Objectives: This revision clarifies terminology, updates Principles with current science and practice, provides expanded Standards of Practice, and improves the Five-star System. Methods: While key elements of the previous version were retained, substantial revisions were made. Results: This document synthesizes eight Principles of ecological restoration and details Standards of Practice spanning assessment, planning, implementation, ongoing management, and monitoring and evaluation. Standards are applicable across ecosystems and biomes, sectors, and diverse social and cultural contexts. Included are: (1) a clarified definition of ecological restoration emphasizing recovery of native ecosystems; (2) refined terminology and updated Standards of Practice; (3) zero-star baselines and increased quantification of the Five-star System; (4) an updated Restorative Continuum that refines the relationships between restorative activities and major restoration types and illustrates application to all major ecosystem types; and (5) expanded discussion of several complex topics. Conclusions: Applying the SER Standards can help reduce risk and uncertainty and enhance ecological restoration outcomes, including creating synergies with other restorative and conservation activities.

Introduction Forest restoration is growing rapidly, increasing demand for reliable and generalizable information on management impacts. However, evidence on the efficacy and adverse effects of treatments, particularly in high-elevation ecosystems, remains limited. Objectives: We monitored the efficacy and ecological effects of mechanical cutting and prescribed burning to restore Pinus albicaulis forests and evaluated the effectiveness of the monitoring design.Methods We used data from a 15-year, replicated before-after-control-impact study to evaluate treatment effects on adult P. albicaulis tree mortality, basal area of competing conifers, and P. albicaulis seedling density. We also quantified the precision of estimation associated with the monitoring design.Results Tree mortality was high (77-100%) within all units, likely reflecting pre-existing Cronartium ribicola infection and a region-wide Dendroctonus ponderosae outbreak rather than treatment effects. Mortality of small-diameter P. albicaulis trees declined with greater basal area removal. Treatments reduced basal area for only one competing conifer, P. contorta. Pinus albicaulis seedling density declined across treatments, with significant effects at only one of 2 units. Despite using widely accepted sampling protocols, the relative margin of error for study variables was high (19, 48 and 73%, respectively, for P. albicaulis basal area, tree mortality, and seedling density).Conclusions Treatments did not fulfill most restoration objectives for P. albicaulis, and widespread disease and insect outbreak impact likely masked treatment effects. Given the likelihood of forest disturbances and that data needs for inference may exceed the scope of individual projects, a coordinated, large-scale, long-term monitoring network is recommended.

The ecological restoration of threatened ecosystems is a global priority, particularly for those with only a few remaining intact fragments. A critical first step in restoring such ecosystems is the development of restoration targets based on the compositional and structural conditions that would have existed in the absence of degradation, which requires a reference model. However, many restoration projects lack adequate reference information, especially regarding spatial structure and species interactions. In this study, we assessed tree species composition, size diversity, and spatial structure in three of the last remaining stands of Nothofagus alessandrii forests in central Chile, with the aim of informing reference models for ecological restoration. Despite relatively high species richness (n = 14-19), the sites exhibited moderate species diversity (Shannon index: 0.62-0.68). All sites showed a negative exponential diameter distribution and moderate size inequality (Gini coefficient approximate to 0.55). Trees were spatially clustered in conspecific groups with radii ranging from 2 to 6 m, and species interaction varied across spatial scales (1-15 m), exhibiting both attraction and repulsion. Smaller trees displayed higher levels of interspecific mingling than larger individuals. Our findings provide critical data for designing restoration prescriptions, evaluating project outcomes, and guiding the spatial pattern of N. alessandrii plantations. More broadly, this study demonstrates the value of incorporating spatial structure and biotic interactions into reference models. Spatially explicit reference conditions, such as those summarized here, offer an ecologically realistic foundation for restoring forest ecosystems.

Global biodiversity targets focus on landscape and seascape connectivity as a foundational component of biodiversity conservation, including networks of connected protected areas. Recent advances allow the measurement and prediction of organismal movements at multiple scales. We provide a definition of connectivity that links movement to persistence and ecological function. Connectivity science can guide planning for biodiversity, ecosystem services, ecological restoration, and climate adaptation. Ongoing climate change and land and sea use are closing the window of opportunity for connectivity conservation. A coordinated global effort is required to implement scientific knowledge and to monitor, map, protect, and restore areas that promote movement and maintain well-connected ecosystems for biodiversity in the long term.

Increased frequency, severity, and duration of droughts and increased wildfire severity are impacting many conifer forests globally. Reforestation in these changing disturbance regimes requires tree seedlings capable of establishing in hotter and drier climates. We evaluated the morphological and physiological effects of drought conditioning on second-year ponderosa pine (Pinus ponderosa), western white pine (Pinus monticola), and western larch (Larix occidentalis) seedlings. Treatments included a well-watered control (75% of container capacity) and a water-limited (40% of container capacity) drought treatment. Ponderosa pine exhibited no significant treatment effects to above or below-ground biomass while treatment caused a significant reduction of height and root-collar diameter for both western white pine and western larch coupled with a significant reduction in root mass for western larch. The drought treatment resulted in significant reductions of gas exchange rates across all species, although mid-day water potentials and delta 13C indicate lack of cumulative stress. Drought conditioned ponderosa pine seedlings resulted in decreased total root nonstructural carbohydrates (NSCs) and droughted western white pine displayed increased total needle NSCs driven by increased needle soluble sugars. Drought conditioning responses in second-year seedlings in large pots proved to be species dependent allowing for further investigation of treatment intensity and duration for drought-adapted stocktypes.

A major barrier globally to achieving restoration goals is the identification and production of appropriate plant materials. To produce high-quality plant materials for restoration success, prevent negative consequences to plant populations, and conserve genetic diversity, it is critical to understand ecotypic variation among plant populations, especially in relation to environmental conditions. For Araucaria araucana, a highly threatened iconic South American tree that grows across a substantial climate gradient, this information is urgently needed to guide restoration and conservation efforts. We conducted a common garden experiment using seedlings from 12 populations of A. araucana across its range in Chile. This approach allowed us to assess regional (coastal versus Andes mountain ranges) and population-level variation in plant traits and relate this variation to environmental variables. Our results demonstrate that A. araucana exhibits differentiation at both regional and population levels, particularly in traits such as branch number and length (indicative of plant architectural differences) and needle width (reflecting variation in leaf investment). This variation is at least partly explained by climate variables, with the most significant differences attributed to regional variations in temperature annual range and mean vapor pressure deficit. Based on these findings, we recommend restoration efforts prioritize conserving genetic variation both among and within regions and their populations, while avoiding translocations of genotypes between coastal and Andes populations.

Recent global initiatives in ecosystem restoration offer an unprecedented opportunity to improve biodiversity conservation and human health and well-being. Ecosystems form a core component of biodiversity. They provide humans with multiple benefits – a stable climate and breathable air; water, food and materials; and protection from disaster and disease. Ecosystem restoration, as defined by the UN Decade on Ecosystem Restoration, includes a range of management interventions that aim to reduce impacts on and assist in the recovery of ecosystems that have been damaged, degraded or destroyed. This Guide promotes the application of the science of ecosystem risk assessment, which involves measuring the risk of ecosystem collapse, in ecosystem restoration. It explores how the IUCN Red List of Ecosystems and ecosystem restoration can be jointly deployed to reduce risk of ecosystem collapse.

Innovation in ecological restoration is necessary to achieve the ambitious targets established in United Nations conventions and other global restoration initiatives. Innovation is also crucial for navigating uncertainties in repairing and restoring ecosystems, and thus practitioners often develop innovations at project design and implementation stages. However, innovation in ecological restoration can be hindered by many factors (e.g., time and budget constraints, and project complexity). Theory and research on innovation has been formally applied in many fields, yet explicit study of innovation in ecological restoration remains nascent. To assess the use of innovation in restoration projects, including its drivers and inhibitors, we conducted a social survey of restoration practitioners in the United States. Specifically, we assessed relationships between project-based innovation and traits of the individual practitioner (including, for example, age, gender, experience); company (including, for example, company size and company’s inclusion of social goals); project (including, for example, complexity and uncertainty); and project outcomes (such as completing the project on time/on budget and personal satisfaction with the work). We found positive relationships between project-based innovation and practitioner traits (age, gender, experience, engagement with research scientists), one company trait (company’s inclusion of social goals in their portfolio), and project traits (project complexity and length). In contrast, two practitioner traits, risk aversion and the use of industry-specific information, were negatively related to project-based innovation. Satisfaction with project outcomes was positively correlated with project-based innovation. Collectively, the results provide insights into the drivers and inhibitors of innovation in restoration and suggest opportunities for research and application.

Questions: Selective herbicides are frequently used in ecological restoration to control invasive non-native forbs and recover plant communities. However, the long-term efficacy of this practice, its non-target effects on native plants, and its role in facilitating secondary invasions are not well understood. Similarly, little is known about the extent to which herbicide drift may affect native plant communities.Location: Foothills grasslands of Montana, USA.Methods: We conducted a 6-year experiment to investigate changes in the abundance of a target invasive plant, knapweed (Centaurea stoebe subsp. micranthos) and plant community structure in response to the herbicides Tordon (R) (picloram) and Milestone (R) (aminopyralid), applied at a recommended rate and a diluted rate that simulated drift.Results: Knapweed cover and the richness of native and non-native forb species declined in the first 3 years in response to treatment at recommended rates, but not drift rates. Secondary invasion by non-native monocots was significant but weak. The cover of native forbs and the cover and richness of native monocots did not differ among treatments but changed significantly with the year. Surprisingly, 6 years after treatments, there were no differences among treatments in the cover of the target invasive plant or community structure.Conclusions: Our results demonstrate that the efficacy and non-target effects of herbicides in grassland restoration can be short-lived and idiosyncratic because of year effects. Restoration of knapweed invasions might require other active interventions, such as seeding or repeated spraying. Our study supports previous calls for long-term monitoring of herbicides application in ecological restoration.

Recent global initiatives in ecosystem restoration offer an unprecedented opportunity to improve biodiversity conservation and human health and well-being. Ecosystems form a core component of biodiversity. They provide humans with multiple benefits – a stable climate and breathable air; water, food and materials; and protection from disaster and disease. Ecosystem restoration, as defined by the UN Decade on Ecosystem Restoration, includes a range of management interventions that aim to reduce impacts on and assist in the recovery of ecosystems that have been damaged, degraded or destroyed. This Guide promotes the application of the science of ecosystem risk assessment, which involves measuring the risk of ecosystem collapse, in ecosystem restoration. It explores how the IUCN Red List of Ecosystems and ecosystem restoration can be jointly deployed to reduce risk of ecosystem collapse.

Whitebark pine (Pinus albicaulis Engelm.) is an ecologically important subalpine and treeline forest tree of the western U.S. and Canada. It is categorized as endangered by the IUCN and by Canada under the Species at Risk Act and was recently proposed for listing in the U.S. as threatened under the Endangered Species Act. Whitebark pine populations are declining nearly rangewide primarily from the spread and intensification of Cronartium ribicola J.C. Fisch., the exotic, invasive pathogen that causes white pine blister rust (WPBR); recent, large-scale outbreaks of mountain pine beetles (MPB) (Dendroctonus ponderosae Hopkins); altered fire regimes; and, multiple impacts from climate change. For more than two decades, researchers and managers within the U.S. Forest Service and Canadian forestry agencies have been developing restoration and conservation tools and techniques to help mitigate these threats. Four conservation and restoration principles for whitebark pine were previously emphasized: (1) conserve genetic diversity, (2) promote WPBR resistance, (3) protect seed sources, and (4) deploy restoration treatments, while mitigating for climate change. These principles are served by ten additional management or conservation actions that form the basis of a restoration and adaptive management plan but apply primarily to regions with moderate to high levels of WPBR and MPB outbreaks. Where the pathogen and MPB are absent or present at low levels, managers can implement proactive management to build resilience to prevent the future loss of ecological function. Here, we review the key management actions currently used for whitebark pine conservation and restoration in the U.S. and Canada, which include gene conservation, increasing natural genetic resistance to C. ribicola, cone collections, growing and planting seedlings or directly sowing seeds, protecting seed sources, prescribed fire and silvicultural thinning to reduce competition in late seral communities, proactive intervention, stand health surveys and monitoring, and monitoring the impacts of restoration for adaptive management. This review is the outcome of an experts' workshop held in association with the development of the National Whitebark Pine Restoration Plan (NWPRP), a collaborative U.S. multi- agency and tribal effort initiated in 2017 in consultation with the U.S. Forest Service and facilitated by the non-profit organizations, the Whitebark Pine Ecosystem Foundation and American Forests.

Large areas of the Panama Canal Watershed have been converted to monocultures of teak (Tectona grandis), a non-native timber species that is generally not providing hoped-for economic and ecological benefits of Forest Landscape Restoration. Enrichment planting offers a potential strategy for revitalizing these underperforming plantations through the addition of high-value, native species to the understory, but more information is needed to guide implementation and management in this region and other tropical areas. We assessed the performance of six promising native species (Byrsonima crassifolia, Dalbergia retusa, Dipteryx oleifera, Hyeronima alchorneoides, Platymiscium pinnatum, Terminalia amazonia) as an enrichment planting in teak plantations, and specifically considered how light availability, crowding pressure and annual fertilization affected seedling performance, we measured survival and growth for the first 30 months post-planting for ∼3,000 seedlings; half received annual fertilization and half did not. We found that growth rate did not significantly affect survival among- or within-species, except for a positive relationship for D. oleifera. Overall seedling survival was high (83%), and, while species varied widely, there was not a strong effect of light, crowding or fertilization on survival. In contrast, overall growth of species was significantly affected by these factors. Across all species growth was negatively related to crowding and positively related to light availability and fertilization. There were among-species differences; while all but one species (D. oleifera) were negatively affected by crowding, only half responded positively to light availability (D. retusa, P. pinnatum, and B. crassifolia) and fertilization (D. retusa, P. pinnatum, and T. amazonia). Our findings suggest that all study species except for B. crassifolia, which suffered unacceptably high mortality, have high potential for use in enrichment planting in Panama teak plantations. Among-species differences in response to fertilization and growing environment highlight the need for continued studies to establish specific silvicultural guidelines for species in the enrichment planting context.

Executive Summary Mining has been, and remains, an integral part of human existence from Stone Age quarries through to the iron and coal that fueled the industrial revolution, to the new materials needed to support the shift to renewable energy. Mining and mining products are major contributors to national economies with mining value tripling in the past two decades. As of 2020, the global mining footprint was 57,000 km 2 and growing at a faster rate now than any other time in human history. Much of this footprint is operational, but in many areas where mining is now complete, the sites represent major environmental liabilities. Although site stabilization and managing waste materials remains a challenging part of mine closure in many parts of the world, the environmental liability of these sites means more than being just safe, stable, and nonpolluting, with companies increasingly expected to restore ecosystems that are representative of their pre‐mined (natural) state. The International Principles and Standards for the Ecological Restoration and Recovery of Mine Sites (Mine Site Restoration Standards, MSRS) present the first international framework for the delivery of socially and environmentally responsible ecological restoration after mining, regardless of whether restoration is legally mandated. The MSRS are designed to inspire and drive higher and better outcomes in post‐mining landscapes by both guiding and encouraging the highest level of restoration achievable that supports the global need for protecting and restoring nature. This comes at a time of unparalleled global human impacts where climate change, land degradation, and biodiversity loss threaten the very ecological fabric of the planet. Mining companies are a major global player in local and regional economies and by demonstrating leadership in protecting, enhancing, and restoring the environments in which they operate, they can maintain, and enhance their social license to operate. The MSRS aim to provide a framework for the mining industry, governments, and stakeholders, including Indigenous peoples and local communities, to address mining‐specific issues in delivering effective restoration of mine sites. The MSRS emphasize that achieving the highest possible ecological outcomes depends upon ingenuity, knowledge investment, and a supportive corporate ethos to build a culture of continuous improvement. This approach will maximize benefits for local communities, the environment, and ultimately the mining industry. For industry, the MSRS provide a framework that can be utilized to optimize restoration outcomes that will leave a positive legacy long after mining has ceased. Early adoption of the MSRS by industry can reduce environmental, financial, and corporate risk in achieving site relinquishment by demonstrating the highest possible commitment to stakeholders, increasing natural capital, responding to climate change and, recovering biodiversity, including threatened and culturally significant species. The agreed‐upon post‐mining land use (PMLU), in some cases, is the same general land use that was present prior to disturbance, which often includes fully functioning intact native ecosystems. In other cases, the PMLU may be different from the pre‐mining condition. Regardless, the potential for ecological restoration should not be invoked as a justification for destroying or damaging existing native ecosystems. When native ecosystems are impacted by mining, full recovery informed by reference models should be the target. Where this is not achievable a “recovery gap” between the initial native ecosystem and the post‐mining ecosystem is created. In highly man‐altered landscapes, processes and approaches to mine site restoration may require local solutions but should be undertaken within the Principles of these Standards. When followed, the MSRS can help limit the recovery gap, and where possible (e.g., if mining is implemented in an ecosystem that had previously been highly degraded by other activities), close that gap and move toward net ecological gain. The Standards are underpinned by eight principles that provide a framework to enable restoration decisions that are evidence‐based, resilient, and acceptable to mining companies, communities, and stakeholders. They are: Engage stakeholders throughout the life of mine. Draw on many types of knowledge. Be informed by reference ecosystems, while considering environmental change. Support ecosystem recovery processes. Assess against clear goals and objectives, using measurable indicators. Seek the highest level of recovery attainable. Gain cumulative value when applied at large scales. Employ a continuum of restorative activities. The MSRS recommend not just best practice, but future practice that harnesses the unique investment and technical capacity of the mining industry and applies it toward the most restorative post‐mining practices possible. These Standards align with the United Nations Decade on Ecosystem Restoration, the United Nations Sustainable Development Goals, The Mitigation Hierarchy, and international best practice in ecological restoration. They build on the International Principles and Standards for the Practice of Ecological Restoration with key concepts customized to meet the unique challenges of global mining. The MSRS represent a living document that will evolve and develop as technological ability, community and environmental expectations, and understanding of mine site restoration changes over time.

As global commitments to restoration are underway, science is needed to support capacity to achieve meaningful gains for ecosystems and human communities. In Chile, identification and generation of appropriate plant material is a barrier to achieving major restoration goals under the Paris Climate Agreement. Understanding genetic differentiation among plant populations is needed to maximize restoration success. For Araucaria araucana, a highly threatened iconic South American tree, this information is greatly needed to guide restoration and conservation efforts because this species occurs across a strong climate gradient. We grew seedlings from 12 populations of A. araucana across its range in Chile in a common garden to assess regional (coastal versus Andes mountain ranges) and population variation in key plant traits and relate this variation to environmental variables. We demonstrate that A. araucana is differentiated within regions and populations across its range in Chile by a suite of traits, particularly branch number and length (showing plant architectural differences) and needle width (showing leaf investment differences). We show that this variation is at least partly explained by climate and soil variables, with the most variation explained by differences between regions in temperature annual range. Thus, we recommend that restoration efforts focus on conserving genetic variation among and within regions and their populations and preventing the translocations of genotypes between coastal and Andes populations.

Context Literature on the ecological impacts of landscape change (LC) has increased dramatically over the last few decades. However, there has not been systematic evidence from a landscape ecology perspective about the evolution of research in this field as well as the main gaps in knowledge. Objectives Our objective was to track the advancement of research on ecological impacts of LC by identifying the main topics, as well as emerging trends, primary findings and main impacts of LC in a Chilean biodiversity hotspot. Methods We used CiteSpace to conduct a bibliometric analysis to represent the knowledge domain and to identify scientific literature related to the impacts of LC in a Chilean biodiversity hotspot between 1990 and 2019. Results We found that articles most frequently focused on compositional attributes of biodiversity (41%) and on analyzing impacts at the community (43%) and population level (34%). In particular, changes in community structure and composition and biologic interactions were the most frequently studied. Research on quantifying forest loss and fragmentation using spatially explicit modeling techniques over a long temporal scale were a turning point in LC impact research. We found several gaps in LC research, including lack of studies that simultaneously address multiple levels of the ecological hierarchy and that address linkages between ecological processes and the provisioning ecosystem services. Conclusions Studies that address the impacts of LC at multiple levels of ecological hierarchies and on ecosystem processes and services are needed. Furthermore, our findings highlight the importance of place-based research syntheses to identify research gaps and meet sustainability goals.

Warming-induced mountain pine beetle (Dendroctonus ponderosae; MPB) outbreaks have caused extensive mortality of whitebark pine (Pinus albicaulis; WBP) throughout the species' range. In the highest mountains where WBP occur, they cross alpine treeline ecotones (ATEs) where growth forms transition from trees to shrub-like krummholz, some of which survived recent MPB outbreaks. This observation motivated the hypothesis that ATEs are refugia for WBP because krummholz growth forms escape MPB attack and have the potential to produce viable seed. To test this hypothesis, we surveyed WBP mortality along transects from the ATE edge (locally highest krummholz WBP) downslope into the forest and, to distinguish if survival mechanisms are unique to ATEs, across other forest ecotones (OFEs) from the edge of WBP occurrence into the forest. We replicated this design at 10 randomly selected sites in the U.S. Northern Rocky Mountains. We also surveyed reproduction in a subset of ATE sites. Mortality was nearly absent in upper ATEs (mean ± SE percent dead across all sites of 0.03% ± 0.03% 0-100 m from the edge and 14.1% ± 1.7% 100-500 m from the edge) but was above 20% along OFEs (21.4 ± 5.2% 0-100 m and 32.4 ± 2.7% 100-500 m from the edge). We observed lower reproduction in upper ATEs (16 ± 9.9 cones/ha and 12.9 ± 5.3 viable seeds/cone 0-100 m from the edge) compared to forests below (317.1 ± 64.4 cones/ha and 32.5 ± 2.5 viable seeds/cone 100-500 m from the edge). Uniquely high WBP survival supports the hypothesis that ATEs serve as refugia because krummholz growth forms escape MPB attack. However, low reproduction suggests ATE refugia function over longer time periods. Beyond our WBP system, we propose that plant populations in marginal environments are candidate refugia if distinct phenotypes result in reduced disturbance impacts.

Despite substantial conservation efforts, the loss of ecosystems continues globally, along with related declines in species and nature's contributions to people. An effective ecosystem goal, supported by clear milestones, targets and indicators, is urgently needed for the post-2020 global biodiversity framework and beyond to support biodiversity conservation, the UN Sustainable Development Goals and efforts to abate climate change. Here, we describe the scientific foundations for an ecosystem goal and milestones, founded on a theory of change, and review available indicators to measure progress. An ecosystem goal should include three core components: area, integrity and risk of collapse. Targets-the actions that are necessary for the goals to be met-should address the pathways to ecosystem loss and recovery, including safeguarding remnants of threatened ecosystems, restoring their area and integrity to reduce risk of collapse and retaining intact areas. Multiple indicators are needed to capture the different dimensions of ecosystem area, integrity and risk of collapse across all ecosystem types, and should be selected for their fitness for purpose and relevance to goal components. Science-based goals, supported by well-formulated action targets and fit-for-purpose indicators, will provide the best foundation for reversing biodiversity loss and sustaining human well-being.

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 limited its utility. We developed a unifying definition and 10 guiding principles for rewilding through a survey of 59 rewilding experts, a summary of key organizations' rewilding visions, and workshops involving over 100 participants from around the world. The guiding principles convey that rewilding exits on 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. These principles clarify the concept of rewilding and improve its effectiveness as a tool to achieve global conservation targets, including those of the UN Decade on Ecosystem Restoration and post-2020 Global Biodiversity Framework. Finally, we suggest differences in rewilding perspectives lie largely in the extent to which it is seen as achievable and in specific interventions. An understanding of the context of rewilding projects is the key to success, and careful site-specific interpretations will help achieve the aims of rewilding.