Abstrakt
Alien species can change the recipient environment in various ways, and some of them cause considerable damage. Understanding such impacts is crucial to direct management actions.
Using the same scoring system for taxa as diverse as invertebrates, vertebrates and plants, we found that overall, alien mammals in Europe have the highest impact, while fish have the lowest. Terrestrial arthropods were found to have the lowest environmental impact, while fish had relatively low socio-economic impact.
For mammals and birds, the impacts in invaded ranges outside of Europe are broadly similar to those recorded for alien species within Europe, indicating that a consideration of the known impacts of a species in other regions can be generally useful when predicting the impacts of an alien species. However, it should be noted that this pattern is not consistent across all mammal and bird orders, and thus, such information should be considered with caution.
Comparing the impacts of alien species across taxa is necessary for prioritizing management efforts and effective allocation of resources. By applying the generic impact scoring system (GISS) to five major taxonomic groups, we provide the basis for a semiquantitative cross-taxa listing process (e.g. 'black lists' or 100-worst-lists).
If more data are collated from different geographical regions and habitats using standard GISS protocols, risk assessments for alien species based on rigorous measures of impact could be improved by taking into account local variation, and context dependence of impacts. This would also allow studies at lower taxonomic levels, and within-taxon analyses of functional groups and guilds.