The impact of land use on non-native species incidence and number in local assemblages worldwide

Risks posed by invasive species to the provision of ecosystem services in Europe

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.

Economic impact disharmony in global biological invasions

A dominant syndrome of the Anthropocene is the rapid worldwide spread of invasive species with devastating environmental and socio-economic impacts. However, the dynamics underlying the impacts of biological invasions remain contested. A hypothesis posits that the richness of impactful invasive species increases proportionally with the richness of non-native species more generally. A competing hypothesis suggests that certain species features disproportionately enhance the chances of non-native species becoming impactful, causing invasive species to arise disproportionately relative to the numbers of non-native species. We test whether invasive species with reported monetary costs reflect global numbers of established non-native species among phyla, classes, and families. Our results reveal that numbers of invasive species with economic costs largely reflect non-native species richness among taxa (i.e., in 96 % of families). However, a few costly taxa were over- and under-represented, and their composition differed among environments and regions. Chordates, nematodes, and pathogenic groups tended to be the most over-represented phyla with reported monetary costs, with mammals, insects, fungi, roundworms, and medically-important microorganisms being over-represented classes. Numbers of costly invasive species increased significantly with non-native richness per taxon, while monetary cost magnitudes at the family level were also significantly related to costly invasive species richness. Costs were biased towards a few 'hyper-costly' taxa (such as termites, mosquitoes, cats, weevils, rodents, ants, and asters). Ordination analysis revealed significant dissimilarity between non-native and costly invasive taxon assemblages. These results highlight taxonomic groups which harbour disproportionately high numbers of costly invasive species and monetary cost magnitudes. Collectively, our findings support prevention of arrival and containment of spread of non-native species as a whole through effective strategies for mitigation of the rapidly amplifying impacts of invasive species. Yet, the hyper- costly taxa identified here should receive greater focus from managers to reduce impacts of current invasive species.

Soil pollution and the invasion of congener Sphagneticola in crop lands

The input of agro-pollutants, such as microplastics and nanopesticides, on farmlands is widespread and may facilitate biological invasions in agroecosystems. Here, the effects of agro-pollutants that promote invasion of congener species is studied by examining the growth performance of native Sphagneticola calendulacea and its invasive congener, S. trilobata, when grown in a native only, invasive only and mixed community. Sphagneticola calendulacea naturally occurs in croplands in southern China, while S. trilobata was introduced to this region and has since naturalized, encroaching onto farmland. In our study, each plant community was subjected to the following treatments: control, microplastics only, nanopesticides only, and both microplastics and nanopesticides. The effects of the treatments on soils of each plant community were also examined. We found that aboveground, belowground, and photosynthetic traits of S. calendulacea were significantly inhibited by the combined microplastics and nanopesticides treatment in the native and mixed communities. The relative advantage index of S. trilobata was 69.90% and 74.73% higher under the microplastics only and nanopesticides only treatments respectively compared to S. calendulacea. Soil microbial biomass, enzyme activity, gas emission rates, and chemicals in each community were reduced when treated with both microplastics and nanopesticides. Yet, soil microbial biomass of carbon and nitrogen, CO₂ emission rates and nitrous oxide rates were significantly higher (56.08%, 58.33%, 36.84% and 49.95% respectively) in the invasive species community than in the native species community under microplastics and nanopesticides. Our results suggest that the addition of agro-pollutants to soils favors the more resistant S. trilobata and suppresses the less tolerant S. calendulacea. Soil properties from the native species community are also more impacted by agro-pollutants than substrates supporting the invasive species. Future studies should explore the effects of agro-pollutants by comparing other invasive and native species and considering human activities, industry, and the soil environment.