Pathways of introduction of alien species in Norway

1. Alien species constitute one of the major threats to global biodiversity. Stopping alien species at an early stage, preferably before establishment, is crucial for the effectiveness of management actions. To enable early detection and prevent future introductions, knowledge of pathways of introduction and their absolute and relative importance is crucial. 2. Based on an exhaustive impact assessment of all alien species in Norway (multicellular neobiota), the relation of taxonomy, lifestyle and ecological impact of alien species to their pathways of introduction are investigated. This taxonomically and ecologically unbiased dataset contains 2,267 unique pathways of 1,180 alien species. 3. Ecological and taxonomic patterns indicate that terrestrial organisms were predominantly introduced by means of escape (mainly plants escaped from gardens), parasites as contaminants (mainly fungi and insects parasitising plants), freshwater organisms by release (mainly vertebrates), and marine organ...