Over 1200 Non-Native Species Are Established in the Iberian Peninsula.

Abstract

Aim: As a consequence of globalisation, biological invasions have become an increasing concern due to multifaceted ecological and socio-economic impacts on biodiversity and ecosystem services. Despite the increasing availability and accessibility of data, a comprehensive assessment of established non-native species and their distribution in the Iberian Peninsula has not been conducted so far. Location: Iberian Peninsula, including Spain, Portugal, Andorra, and Gibraltar. Methods: We compiled a harmonised dataset of 1273 established non-native species from multiple regional, national, and global sources. We analysed taxonomic composition, introduction pathways, and native biogeographic realms. Temporal patterns were assessed using first-record data, while spatial patterns were mapped using high-resolution occurrence data from GBIF and national databases. Results: The majority of established non-native species are vascular plants and insects, specifically of the classes Magnoliopsida and Insecta and the families Asteraceae and Formicidae, respectively. Overall, the most common pathways of introduction were escapes from human facilities and transport-related mechanisms (contaminant and stowaway), but their importance varies among countries. Established non-native species were mostly native to the other regions within the Palearctic, followed by the Nearctic and Neotropical realms. Regarding the time of introduction, first records increased steadily until the last decades of the 20th century, when the introduction rate slowed down; yet new introductions persist. Finally, our spatial analysis identified that areas with high human population density and coastal zones recorded the highest number of established non-native species. Main Conclusion: The Iberian Peninsula hosts a high number and diversity of established non-native species. Given the ongoing rise in cumulative introductions and the role of unintentional human-driven pathways, strengthening prevention measures is vital to reduce future invasions. However, with many non-native species already established, effective management efforts are equally crucial to curb further spread and mitigate consequent impacts, especially in areas of conservation interest.