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Citation: Sandvik, H., and B.-E. Sæther (2012) Ecological impact assessment of alien species: generic and quantitative classification criteria. – Talk given at the 3rd European Congress of Conservation Biology in Glasgow. Abstract: Risk communication about and management of alien species could be greatly improved by a generic ecological set of "Black List" criteria, analogous to the criteria used in classifying threatened species in Red Lists. We present a set of criteria that meets this requirement. It is generic in the sense of being applicable to all taxonomic groups and all habitats. In contrast to most previous classification schemes of alien species, it is quantitative and, therefore, transparent, testable, and easily adjustable to new knowledge or changing environmental conditions. The classification system is two-dimensional: it assesses the ecological impact of species along two independent axes, one measuring invasion potential, and the other ecological effects. Invasion potential is determined based on the estimated spread velocity; on the expected population lifetime; and on the proportion of different habitat types that are projected to be occupied. Ecological effect is inferred from interactions with native species; from state changes brought about in landscapes; and from the probability of transmission of genetic material and/or parasites to native species. Effects on threatened native species, and state changes in rare landscape elements, receive greater weight. The set of criteria is currently applied to all known alien species of Norway. Related publications: The set of criteria has now been published in Biodiversity and Conservation.
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