Viewpoint Managing non-native

Biological invasion is a controversial issue, even with respect to its own definition. From an ecological point of view, invasive alien species are those spreading in a novel environment (the geographical criterion). How-ever, some researchers and managers believe that a spe-cies must have a major impact on the novel environment to be considered invasive (the impact cri-terion) (Valéry et al. 2008). This distinction is not triv-ial: alien invasions are considered among the major threats to biodiversity and there is a heated debate on why and how to deal with them (Davis et al. 2011, Simberloff 2011a, Lambertini et al. 2011). In a recent article, Bauer and Woog (2011) pose the question whether the limited resources, political will and public support available should be targeted at non