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Invasive alien species are one of the major threats to global biodiversity, ecosystem integrity, nature's contributions to people and human health. While scenarios about potential future developments have been available for other global change drivers for quite some time, we largely lack an understanding of how biological invasions might unfold in the future across spatial scales. Based on previous work on global invasion scenarios, we developed a workflow to downscale global scenarios to a regional and policy-relevant context. We applied this workflow at the European scale to create four European scenarios of biological invasions until 2050 that consider different environmental, socio-economic and socio-cultural trajectories, namely the European Alien Species Narratives (Eur-ASNs). We compared the Eur-ASNs with their previously published global counterparts (Global-ASNs), assessing changes in 26 scenario variables. This assessment showed a high consistency between global and European scenarios in the logic and assumptions of the scenario variables. However, several discrepancies in scenario variable trends were detected that could be attributed to scale differences. This suggests that the workflow is able to capture scale-dependent differences across scenarios. We also compared the Global- and Eur-ASNs with the widely used Global and European Shared Socioeconomic Pathways (SSPs), a set of scenarios developed in the context of climate change to capture different future socio-economic trends. Our comparison showed considerable divergences in the scenario space occupied by the different scenarios, with overall larger differences between the ASNs and SSPs than across scales (global vs. European) within the scenario initiatives. Given the differences between the ASNs and SSPs, it seems that the SSPs do not adequately capture the scenario space relevant to understanding the complex future of biological invasions. This underlines the importance of developing independent b

Future dynamics of biological invasions are highly uncertain because they depend on multiple social-ecological drivers. We used a scenario-based approach to explore potential management options for invasive species in Europe. During two workshops involving a multidisciplinary team of experts, we developed a management strategy arranged into 19 goals relating to policy, research, public awareness, and biosecurity. We conceived solutions for achieving these goals under different plausible future scenarios, and identified four interrelated recommendations around which any long-term strategy for managing invasive species can be structured: (1) a European biosecurity regime, (2) a dedicated communication strategy, (3) data standardization and management tools, and (4) a monitoring and assessment system. Finally, we assessed the feasibility of the management strategy and found substantial differences among scenarios. Collectively, our results indicate that it is time for a new strategy for managing biological invasions in Europe, one that is based on a more integrative approach across socioeconomic sectors and countries.

Biological invasion is recognised as one of the major threats to biodiversity, particularly in disturbance-prone ecosystems such as costal dunes. Many studies have associated alien plant invasion of dune ecosystem to human disturbances, but less is known about the role of soil properties in invasion after disturbance. Soil properties are crucial filters during plant succession and soil-related changes in the initial stage of species colonization might shape the final success of the invaders. We performed a manipulative experiment aimed at elucidating the effects of soil properties on plant colonization processes in highly invaded dune systems, as a proxy for plausible management actions to curb the success of exotic plant species over native ones, which was measured through species richness and abundance. In a barrier island of the Marano and Grado lagoon, Northern Adriatic Sea, we mechanically removed all the native and alien vegetation present in the back dune (also known as secondary dune), triggering a new ecological succession and further altered, for the following three months, soil properties by adding salt, nitrogen, and organic matter in a full factorial design with randomized blocks. The soil treatments reduced the overall species richness and abundance of alien plants. Further, soil treatment interactions strongly shaped community evenness and species richness. Soil salinity had a positive effect on native cover while decreasing the overall number of alien species, especially in soil with added organic matter. Our findings suggest that soil salinity, and its interplay with organic matter, might significantly reduce the initial success of alien species propagule pressure (i.e. alien plant germination), with likely implications for the trajectories of future plant communities. This study highlights that alien plant containment should be focused on early stages of succession, giving new perspective on future environmental management actions for dune restorat

The negative interaction between multiple invasive species, when an invasive predator benefits from a previously introduced and abundant prey, poses unanticipated challenges for the joint management of invaders. To illustrate this question, we describe the surge and collapse of the invasive apple snail Pomacea maculata population before and after the arrival of the invasive blue crab, Callinectes sapidus, in the Ebro River (NE Spain). These two invaders have coincided for the first time beyond their respective native and prior invasive ranges, and thus lack any previous shared eco-evolutionary history facilitating coexistence. We leverage data from a 9-year apple snail removal programme (2014–2022) conducted by authorities to evaluate the effectiveness of the management programme and describe the apple snail temporal dynamics in the Ebro River. Since its arrival in 2013, the apple snail population increased exponentially along the river and adjacent rice-fields despite labour-intensive eradication efforts. Unexpectedly, riverine populations of the apple snail declined by 90% in 2018 relative to the prior year without apparent association with previous management efforts. Simultaneously, the blue crab was first recorded in the Ebro River in 2018, and its distribution rapidly overlapped the whole area invaded by apple snails. We suggest that over-predation by the blue crab is the main cause of the decline observed in the apple snail, and discuss the implications of this new invader-invader interaction for management. This study underscores the unforeseen consequences of subsequent waves of invasion, and the importance of supporting management with a deeper understanding of ecological interactions among invasive predator and prey species., invader interaction

Although invasive alien species have long been recognized as a major threat to nature and people, until now there has been no comprehensive global review of the status, trends, drivers, impacts, management and governance challenges of biological invasions. The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) Thematic Assessment Report on Invasive Alien Species and Their Control (hereafter 'IPBES invasive alien species assessment') drew on more than 13,000 scientific publications and reports in 15 languages as well as Indigenous and local knowledge on all taxa, ecosystems and regions across the globe. Therefore, it provides unequivocal evidence of the major and growing threat of invasive alien species alongside ambitious but realistic approaches to manage biological invasions. The extent of the threat and impacts has been recognized by the 143 member states of IPBES who approved the summary for policymakers of this assessment. Here, the authors of the IPBES assessment outline the main findings of the IPBES invasive alien species assessment and highlight the urgency to act now.

Future dynamics of biological invasions are highly uncertain because they depend on multiple social–ecological drivers. We used a scenario-based approach to explore potential management options for invasive species in Europe. During two workshops involving a multidisciplinary team of experts, we developed a management strategy arranged into 19 goals relating to policy, research, public awareness, and biosecurity. We conceived solutions for achieving these goals under different plausible future scenarios, and identified four interrelated recommendations around which any long-term strategy for managing invasive species can be structured: (1) a European biosecurity regime, (2) a dedicated communication strategy, (3) data standardization and management tools, and (4) a monitoring and assessment system. Finally, we assessed the feasibility of the management strategy and found substantial differences among scenarios. Collectively, our results indicate that it is time for a new strategy for managing biological invasions in Europe, one that is based on a more integrative approach across socioeconomic sectors and countries.

The Environmental Impact Classification for Alien Taxa (EICAT) is an important tool for biological invasion policy and management and has been adopted as an International Union for Conservation of Nature (IUCN) standard to measure the severity of environmental impacts caused by organisms living outside their native ranges. EICAT has already been incorporated into some national and local decision-making procedures, making it a particularly relevant resource for addressing the impact of non-native species. Recently, some of the underlying conceptual principles of EICAT, particularly those related to the use of the precautionary approach, have been challenged. Although still relatively new, guidelines for the application and interpretation of EICAT will be periodically revisited by the IUCN community, based on scientific evidence, to improve the process. Some of the criticisms recently raised are based on subjectively selected assumptions that cannot be generalized and may harm global efforts to manage biological invasions. EICAT adopts a precautionary principle by considering a species’ impact history elsewhere because some taxa have traits that can make them inherently more harmful. Furthermore, non-native species are often important drivers of biodiversity loss even in the presence of other pressures. Ignoring the precautionary principle when tackling the impacts of non-native species has led to devastating consequences for human well-being, biodiversity, and ecosystems, as well as poor management outcomes, and thus to significant economic costs. EICAT is a relevant tool because it supports prioritization and management of non-native species and meeting and monitoring progress toward the Kunming–Montreal Global Biodiversity Framework (GBF) Target 6.

1. Invasive alien species are one of the major threats to global biodiversity, ecosystem integrity, nature's contributions to people and human health. While scenarios about potential future developments have been available for other global change drivers for quite some time, we largely lack an understanding of how biological invasions might unfold in the future across spatial scales. 2. Based on previous work on global invasion scenarios, we developed a workflow to downscale global scenarios to a regional and policy-relevant context. We applied this workflow at the European scale to create four European scenarios of biological invasions until 2050 that consider different environmental, socio-economic and socio-cultural trajectories, namely the European Alien Species Narratives (Eur-ASNs). 3. We compared the Eur-ASNs with their previously published global counterparts (Global-ASNs), assessing changes in 26 scenario variables. This assessment showed a high consistency between global and European scenarios in the logic and assumptions of the scenario variables. However, several discrepancies in scenario variable trends were detected that could be attributed to scale differences. This suggests that the workflow is able to capture scale-dependent differences across scenarios. 4. We also compared the Global- and Eur-ASNs with the widely used Global and European Shared Socioeconomic Pathways (SSPs), a set of scenarios developed in the context of climate change to capture different future socio-economic trends. Our comparison showed considerable divergences in the scenario space occupied by the different scenarios, with overall larger differences between the ASNs and SSPs than across scales (global vs. European) within the scenario initiatives. 5. Given the differences between the ASNs and SSPs, it seems that the SSPs do not adequately capture the scenario space relevant to understanding the complex future of biological invasions. This underlines the importance of developin

The impacts of invasive species can vary widely across invaded sites and depend on the ecological variable of study. In this paper, we describe the first harmonised database that compiles scientific evidence of the ecological impacts of invasive plant species at continental scale. We summarise results from 266 publications reporting 4259 field studies on 104 invasive species in 29 European countries. For each study, we recorded whether the effects were statistically significant and noted their direction (i.e. decrease or increase in the response variable when compared to uninvaded sites). We classified studies, based on the impacts on the levels of ecological organisation (species, communities and ecosystems), taxa and trophic level. More than half of the studies were conducted in temperate and boreal forests and woodlands and temperate grasslands. Notably, one third of the studies focused on just five invasive species. Most studies were on native species followed by studies on communities. Impacts on plants were more frequently studied than impacts on other taxa and trophic groups. Overall, 43% of the studies reported significant impacts, with more significant decreases (26%) than increases (17%) in the response variables. Significant impacts were more frequent on species and communities than on ecosystems; and on plants than on animals or microbes. This database is of interest for academic, management and policy-related purposes.

Invasive species significantly impact biodiversity and ecosystem services, yet understanding these effects at large spatial scales remains a challenge. Our study addresses this gap by assessing the current and potential future risks posed by 94 invasive species to seven key ecosystem services in Europe. We demonstrate widespread potential impacts, particularly on outdoor recreation, habitat maintenance, crop provisioning, and soil and nitrogen retention. Exposure to invasive species was higher in areas with lower provision of ecosystem services, particularly for regulating and cultural services. Exposure was also high in areas where ecosystem contributions to crop provision and nitrogen retention were at their highest. Notably, regions vital for ecosystem services currently have low invasion suitability, but face an average 77% increase in potential invasion area. Here we show that, while high-value ecosystem service areas at the highest risk represent a small fraction of Europe (0-13%), they are disproportionally important for service conservation. Our study underscores the importance of monitoring and protecting these hotspots to align management strategies with international biodiversity targets, considering both invasion vulnerability and ecosystem service sustainability.

Future dynamics of biological invasions are highly uncertain because they depend on multiple social–ecological drivers. We useda scenario-based approach to explore potential management options for invasive species in Europe. During two workshops involv-ing a multidisciplinary team of experts, we developed a management strategy arranged into 19 goals relating to policy, research,public awareness, and biosecurity. We conceived solutions for achieving these goals under different plausible future scenarios, andidentified four interrelated recommendations around which any long-term strategy for managing invasive species can be struc-tured: a European biosecurity regime, a dedicated communication strategy, data standardization and managementtools, and a monitoring and assessment system. Finally, we assessed the feasibility of the management strategy and found sub-stantial differences among scenarios. Collectively, our results indicate that it is time for a new strategy for managing biologicalinvasions in Europe, one that is based on a more integrative approach across socioeconomic sectors and countries

The Environmental Impact Classification for Alien Taxa (EICAT) is an important tool for biological invasion policy and management and has been adopted as an International Union for Conservation of Nature (IUCN) standard to measure the severity of environmental impacts caused by organisms living outside their native ranges. EICAT has already been incorporated into some national and local decision-making procedures, making it a particularly relevant resource for addressing the impact of non-native species. Recently, some of the underlying conceptual principles of EICAT, particularly those related to the use of the precautionary approach, have been challenged. Although still relatively new, guidelines for the application and interpretation of EICAT will be periodically revisited by the IUCN community, based on scientific evidence, to improve the process. Some of the criticisms recently raised are based on subjectively selected assumptions that cannot be generalized and may harm global efforts to manage biological invasions. EICAT adopts a precautionary principle by considering a species’ impact history elsewhere because some taxa have traits that can make them inherently more harmful. Furthermore, non-native species are often important drivers of biodiversity loss even in the presence of other pressures. Ignoring the precautionary principle when tackling the impacts of non-native species has led to devastating consequences for human well-being, biodiversity, and ecosystems, as well as poor management outcomes, and thus to significant economic costs. EICAT is a relevant tool because it supports prioritization and management of non-native species and meeting and monitoring progress toward the Kunming–Montreal Global Biodiversity Framework (GBF) Target 6.