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The invasive apple snail (Pomacea maculata) appeared in 2010 in the Ebro Delta Natural Park, an important area for rice production and waterbird conservation in the eastern Mediterranean. To control crop damage, farmers stopped flooding their rice fields in winter, an agri-environmental scheme (AES) applied for more than 20 years in some European and American regions to favor flora and fauna from wetlands, including wintering waterbirds. Thus, apple snail control is controversial because of its potential side effects on international waterbird conservation efforts. Despite the fact that 10 years have passed since the first flooding limitations, and the alarms raised by the managers of the Natural Park, the side effects of apple snail management on waterbird conservation have not been evaluated. Here we fill this gap by analyzing a 35-year time series to assess whether abundance trends of 27 waterbird species, from five functional groups, decreased in the Ebro Delta after stopping winter flooding. We considered the effects of confounding local factors by also assessing trend changes in l’Albufera, a similar nearby not invaded wetland where flooding has not been interrupted. In addition, as a control of the positive effect of winter flooding, we also assessed whether abundance trends increased in both wetlands after applying this AES winter flooding. Our results showed complex and decoupled trend changes across species and geographical areas, without statistical evidences, in general or for any particular functional group, on the positive effect of winter flooding in both wetlands neither on the negative effect of its cessation in Ebro Delta. These results suggest the safety of this apple snail control in terms of waterbird abundance at a landscape scale. In addition, these results question, at least in two important wintering areas in Europe, the attractor role associated with the flooding agri-environmental scheme applied for decades.

Invasive alien species (IAS) are one of the main threats to biodiversity conservation, with significant socio-economic and ecological impacts as they disrupt ecosystem services and compromise human well-being. Global change may exacerbate the impacts of IAS, since rising temperatures and human activities favour their introduction and range expansion. Therefore, anticipating the impacts of biological invasions is crucial to support decision-making for their management. In this work, the potential impacts of four invasive alien plant species: Ailanthus altissima, Baccharis halimifolia, Impatiens glandulifera and Pueraria montana, on the provision of three ecosystem services in Europe were evaluated under current and future climate change scenarios. Using a risk analysis protocol, we determined that the most affected services are food provisioning, soil erosion regulation and the maintenance of biological diversity. To evaluate future impacts, species distribution models were calibrated using bioclimatic, environmental and human impact variables. We found that most of continental Europe is suitable for the establishment of A. altissima, B. halimifolia and I. glandulifera, while the potential distribution of P. montana is more limited. Models anticipate a shift in the distribution range for the species towards the north and east of Europe under future scenarios. Bivariate analysis allowed the identification of trends for future impacts in ecosystem services by simultaneously visualising the potential distribution of invasive species and the provision of ecosystem services. Our models project an increase in critical and high impact areas on the analysed ecosystem services, with Western Europe and the British Isles as the most affected regions. In comparison, lower impacts are projected for the Mediterranean region, likely as a consequence of the northwards expansion of invaders. Measures need to be taken to mitigate the expansion and impact of invasive species as our wor

Impact assessments can help prioritising limited resources for invasive species management. However, their usefulness to provide information for decision-making depends on their repeatability, i.e. the consistency of the estimated impact. Previous studies have provided important insights into the consistency of final scores and rankings. However, due to the criteria to summarise protocol responses into one value (e.g. maximum score observed) or to categorise those final scores into prioritisation levels, the real consistency at the answer level remains poorly understood. Here, we fill this gap by quantifying and comparing the consistency in the scores of protocol questions with inter-rater reliability metrics. We provide an overview of impact assessment consistency and the factors altering it, by evaluating 1,742 impact assessments of 60 terrestrial, freshwater and marine vertebrates, invertebrates and plants conducted with seven protocols applied in Europe (EICAT; EPPO; EPPO prioritisation; GABLIS; GB; GISS; and Harmonia+). Assessments include questions about diverse impact types: environment, biodiversity, native species interactions, hybridisation, economic losses and human health. Overall, the great majority of assessments (67%) showed high consistency; only a small minority (13%) presented low consistency. Consistency of responses did not depend on species identity or the amount of information on their impacts, but partly depended on the impact type evaluated and the protocol used, probably due to linguistic uncertainties (pseudo-R2 = 0.11 and 0.10, respectively). Consistency of responses was highest for questions on ecosystem and human health impacts and lowest for questions regarding biological interactions amongst alien and native species. Regarding protocols, consistency was highest with Harmonia+ and GISS and lowest with EPPO. The presence of few, but very low, consistent assessments indicates that there is room for improvement in the repeatability of asse

Species introduced through human-related activities beyond their native range, termed alien species, have various impacts worldwide. The IUCN Environmental Impact Classification for Alien Taxa (EICAT) is a global standard to assess negative impacts of alien species on native biodiversity. Alien species can also positively affect biodiversity (for instance, through food and habitat provisioning or dispersal facilitation) but there is currently no standardized and evidence-based system to classify positive impacts. We fill this gap by proposing EICAT+, which uses 5 semiquantitative scenarios to categorize the magnitude of positive impacts, and describes underlying mechanisms. EICAT+ can be applied to all alien taxa at different spatial and organizational scales. The application of EICAT+ expands our understanding of the consequences of biological invasions and can inform conservation decisions.

Agricultural expansion and intensification have boosted global food production but have come at the cost of environmental degradation and biodiversity loss. Biodiversity-friendly farming that boosts ecosystem services, such as pollination and natural pest control, is widely being advocated to maintain and improve agricultural productivity while safeguarding biodiversity. A vast body of evidence showing the agronomic benefits of enhanced ecosystem service delivery represent important incentives to adopt practices enhancing biodiversity. However, the costs of biodiversity-friendly management are rarely taken into account and may represent a major barrier impeding uptake by farmers. Whether and how biodiversity conservation, ecosystem service delivery, and farm profit can go hand in hand is unknown. Here, we quantify the ecological, agronomic, and net economic benefits of biodiversity-friendly farming in an intensive grassland–sunflower system in Southwest France. We found that reducing land-use intensity on agricultural grasslands drastically enhances flower availability and wild bee diversity, including rare species. Biodiversity-friendly management on grasslands furthermore resulted in an up to 17% higher revenue on neighboring sunflower fields through positive effects on pollination service delivery. However, the opportunity costs of reduced grassland forage yields consistently exceeded the economic benefits of enhanced sunflower pollination. Our results highlight that profitability is often a key constraint hampering adoption of biodiversity-based farming and uptake critically depends on society’s willingness to pay for associated delivery of public goods such as biodiversity.

One of the most invoked mechanisms mediating the positive effect of pollinator diversity on plant reproduction is pollinator's niche complementarity (i.e. partitioning of resource use by different pollinator species). However, the influence of spatial and temporal pollinator's niche complementarity on crop pollination function is rarely tested. We investigated the influence of spatial and temporal niche complementary in explaining sunflower crop production by comparing pollination activity at the edge and centre of crop fields and over the day. We found weaker evidence for spatial niche complementarity than for temporal niche complementarity in pollinator visitation rates. Only the visitation rate of hoverflies slightly differed between the centre and the edge of the fields. Nevertheless, we observed no differences in seed weight between the edge and the centre of the fields, but interestingly, plants allowed to be pollinated only by small-sized pollinators experienced a decline in seed production with distance from the edge. Pollinators did show complementary peak activity periods throughout the day, with Bombus terrestris and honeybees preferring to forage early in the day and at cooler temperatures than B. lapidarius and solitary bees. Unexpectedly, only morning- and only afternoon-pollinated plants produced similar seed weights, but these were higher than in all-day exposed plants. These findings indicate that sunflower fields shelter a small number of complementary pollinator species groups, which become rapidly redundant as diversity increases. Overall, we show that temporal and spatial niche complementarity effects on yield can unfold in unexpected ways, which are hard to predict without testing for the specific mechanisms.

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

Upon arrival to a new area, alien species have to overcome a series of biotic and abiotic barriers to survive, reproduce, and spread and thus, succeed along the invasion continuum. Failing to understand the role of the different sets of barriers and factors operating across the stages of the invasion continuum limit our ability to predict invasion dynamics, leading to misinformed management. Here, we explore how the European plant Cytisus scoparius overcomes the survival and reproductive barriers to establish along the roadsides of Nahuel Huapi National Park (Argentina). We evaluate the direct and indirect influence of climatic and landscape factors, species traits and their interaction with patch cover, plant height, and pollinator visitation rates as proxies of population persistence, plant growth, and reproduction, respectively. Cytisus scoparius cover was positively associated with the length of water shores and urban cover, factors that may relate to the arrival of propagules, new introduction events, and high levels of disturbance. Plant height was positively associated with annual precipitation and mean temperature. Visitation rates positively related to shrubland cover and to a lesser extent to slope, two factors that may influence pollinator availability and long-distance detectability, respectively. However, factors positively affecting survival had no effect (in the case of height) or negative effect (in the case of cover) on visitation rates, probably due to the saturation of the pollinator pool within large flowering patches. Despite the strong environmental gradients, climatic variables did not seem to influence the cover nor the visitation rates of C. scoparius. The microhabitat provided by roadsides seemed to buffer the climatic variability acting at larger spatial scales. This study shows how the relevance of different barriers across the invasion process can vary due to the characteristics of the species and of the spatial context. Actions directed

A major aim in invasion ecology is to understand the role of exotic species in plant communities. Whereas most studies have explored the traits of exotic species in the context of the introduced community, functional comparisons of entire assemblages of species in their native and introduced communities have rarely been analysed. Taking advantage of the unidirectional invasion of plant species of European origin (i.e. colonizers) into California, this study aims to investigate the relative importance of plant traits, environmental factors and invasion status in biological invasions. We compared the functional structure (i.e. trait composition and diversity) along resource availability gradients in recipient and native Mediterranean grassland communities in California and Spain, respectively. Traits were related to resource use in above-ground and below-ground organs and reproductive strategy. We also investigated how niche differences vary along environmental gradients between coexisting colonizer and native species assemblages within communities. There were clear differences in the functional structure of Mediterranean grassland communities between regions, which were associated with the resource availability gradient. Paradoxically, the most acquisitive communities occurred in resource-poor sites, highlighting that rapid acquisition and use of resources permit species to cope with environmental stress through stress avoidance. In Spain, colonizer species had greater specific leaf area than non-colonizers. Yet, differences between colonizer and non-colonizer species in Spain for other traits were mostly absent and did not change along the gradient. This might be a result of the greater native species richness as a consequence of the agricultural practices that have taken place in Europe for millennia and reflect that the entire species pool of grasslands is adapted to agricultural landscapes. In comparison, in California, colonizer species were more acquisitive in

Invasive alien species have widespread impacts on native biodiversity and ecosystem services. Since the number of introductions worldwide is continuously rising, it is essential to prevent the entry, establishment and spread of new alien species through a systematic examination of future potential threats. Applying a three-step horizon scanning consensus method, we evaluated non-established alien species that could potentially arrive, establish and cause major ecological impact in Spain within the next 10 years. Overall, we identified 47 species with a very high risk (e.g. Oreochromis niloticus, Popillia japonica, Hemidactylus frenatus, Crassula helmsii or Halophila stipulacea), 61 with high risk, 93 with moderate risk, and 732 species with low risk. Many of the species categorized as very high or high risk to Spanish biodiversity are either already present in Europe and neighbouring countries or have a long invasive history elsewhere. This study provides an updated list of potential invasive alien species useful for prioritizing efforts and resources against their introduction. Compared to previous horizon scanning exercises in Spain, the current study screens potential invaders from a wider range of terrestrial, freshwater, and marine organisms, and can serve as a basis for more comprehensive risk analyses to improve management and increase the efficiency of the early warning and rapid response framework for invasive alien species. We also stress the usefulness of measuring agreement and consistency as two different properties of the reliability of expert scores, in order to more easily elaborate consensus ranked lists of potential invasive alien species.

Invasive species science has focused heavily on the invasive agent. However, management to protect native species also requires a proactive approach focused on resident communities and the features affecting their vulnerability to invasion impacts. Vulnerability is likely the result of factors acting across spatial scales, from local to regional, and it is the combined effects of these factors that will determine the magnitude of vulnerability. Here, we introduce an analytical framework that quantifies the scale-dependent impact of biological invasions on native richness from the shape of the native species–area relationship (SAR). We leveraged newly available, biogeographically extensive vegetation data from the U.S. National Ecological Observatory Network to assess plant community vulnerability to invasion impact as a function of factors acting across scales. We analyzed more than 1000 SARs widely distributed across the USA along environmental gradients and under different levels of non-native plant cover. Decreases in native richness were consistently associated with non-native species cover, but native richness was compromised only at relatively high levels of non-native cover. After accounting for variation in baseline ecosystem diversity, net primary productivity, and human modification, ecoregions that were colder and wetter were most vulnerable to losses of native plant species at the local level, while warmer and wetter areas were most susceptible at the landscape level. We also document how the combined effects of cross-scale factors result in a heterogeneous spatial pattern of vulnerability. This pattern could not be predicted by analyses at any single scale, underscoring the importance of accounting for factors acting across scales. Simultaneously assessing differences in vulnerability between distinct plant communities at local, landscape, and regional scales provided outputs that can be used to inform policy and management aimed at reducing vulnerabili

Aim: Native biodiversity is threatened by the spread of non-native invasive species. Many studies demonstrate that invasions reduce local biodiversity but we lack an understanding of how impacts vary across environments at the macroscale. Using ~11,500 vegetation surveys from ecosystems across the United States, we quantified how the relationship between non-native plant cover and native plant diversity varied across different compositions of invading plants (measured by non-native plant richness and evenness) and environmental contexts (measured by productivity and human activity). Location: Continental United States. Time Period: Surveys from 1990s-present. Major Taxa Studied: Terrestrial plant communities. Methods: We fit mixed effects models to understand how native plant richness, diversity and evenness varied with non-native cover. We tested how this relationship varied when non-native cover interacted with non-native plant richness and evenness, and with productivity and human activity. Results: Across the United States, communities with greater cover of non-native plants had lower native plant richness and diversity but higher evenness, suggesting rare native plants can be lost while dominant plants decline in abundance. The relationship between non-native cover and native community diversity varied with non-native plant richness and evenness but was not associated with productivity and human activity. Negative associations were strongest in areas with low non-native richness and evenness, characterizing plant communities that were invaded by a dominant non-native plant. Main Conclusions: Non-native plant cover provides a first approximation of invasion impacts on native community diversity, but the magnitude of impact depended on non-native plant richness and evenness. Relationships between non-native cover and native diversity were consistent in strength across continental scale gradients of productivity and human activity. Therefore, at the macroscale, in

1. Pollinators benefit from increasing floral resources in agricultural landscapes, which could be an underexplored co-benefit of mass-flowering crop cultivation. However, the impacts of mass-flowering crops on pollinator communities are complex and appear to be context-dependent, mediated by factors such as crop flowering time and the availability of other flower resources in the landscape. A synthesis of research is needed to develop management recommendations for effective pollinator conservation in agroecosystems. 2. By combining 22 datasets from 13 publications conducted in nine temperate countries (20 European, 2 North American), we investigated if mass-flowering crop flowering time (early or late season), bloom state (during or after crop flowering) and extent of non-crop habitat cover in the landscape moderated the effect of mass-flowering crop cover on wild pollinator abundance and species richness in mass-flowering crop and non-crop habitats. 3. During bloom, wild bee abundance and richness are negatively related to mass-flowering crop cover. Dilution effects were predominant in crop habitats and early in the season, except for bumblebees, which declined with mass-flowering crop cover irrespective of habitat or season. Late in the season and in non-crop habitats, several of these negative relationships were either absent or reversed. Late-season mass-flowering crop cover is positively related to honeybee abundance in crop habitats and to other bee abundance in non-crop habitats. These results indicate that crop-adapted species, like honeybees, move to forage and concentrate on late-season mass-flowering crops at a time when flower availability in the landscape is limited, potentially alleviating competition for flower resources in non-crop habitats. We found no evidence of pollinators moving from mass-flowering crop to non-crop habitats after crop bloom. 4. Synthesis and applications: Our results confirm that increasing early-season mass-flowering crop cov

Agricultural expansion and intensification have boosted global food production but have come at the cost of environmental degradation and biodiversity loss. Biodiversity-friendly farming that boosts ecosystem services, such as pollination and natural pest control, is widely being advocated to maintain and improve agricultural productivity while safeguarding biodiversity. A vast body of evidence showing the agronomic benefits of enhanced ecosystem service delivery represent important incentives to adopt practices enhancing biodiversity. However, the costs of biodiversity-friendly management are rarely taken into account and may represent a major barrier impeding uptake by farmers. Whether and how biodiversity conservation, ecosystem service delivery, and farm profit can go hand in hand is unknown. Here, we quantify the ecological, agronomic, and net economic benefits of biodiversity-friendly farming in an intensive grassland-sunflower system in Southwest France. We found that reducing land-use intensity on agricultural grasslands drastically enhances flower availability and wild bee diversity, including rare species. Biodiversity-friendly management on grasslands furthermore resulted in an up to 17% higher revenue on neighboring sunflower fields through positive effects on pollination service delivery. However, the opportunity costs of reduced grassland forage yields consistently exceeded the economic benefits of enhanced sunflower pollination. Our results highlight that profitability is often a key constraint hampering adoption of biodiversity-based farming and uptake critically depends on society's willingness to pay for associated delivery of public goods such as biodiversity.

Invasive alien species have widespread impacts on native biodiversity and ecosystem services. Since the number of introductions worldwide is continuously rising, it is essential to prevent the entry, establishment and spread of new alien species through a systematic examination of future potential threats. Applying a three-step horizon scanning consensus method, we evaluated non-established alien species that could potentially arrive, establish and cause major ecological impact in Spain within the next 10 years. Overall, we identified 47 species with a very high risk (e.g. Oreochromis niloticus, Popillia japonica, Hemidactylus frenatus, Crassula helmsii or Halophila stipulacea), 61 with high risk, 93 with moderate risk, and 732 species with low risk. Many of the species categorized as very high or high risk to Spanish biodiversity are either already present in Europe and neighbouring countries or have a long invasive history elsewhere. This study provides an updated list of potential invasive alien species useful for prioritizing efforts and resources against their introduction. Compared to previous horizon scanning exercises in Spain, the current study screens potential invaders from a wider range of terrestrial, freshwater, and marine organisms, and can serve as a basis for more comprehensive risk analyses to improve management and increase the efficiency of the early warning and rapid response framework for invasive alien species. We also stress the usefulness of measuring agreement and consistency as two different properties of the reliability of expert scores, in order to more easily elaborate consensus ranked lists of potential invasive alien species.