Fig 1. Illustration of EICAT and EICAT+ scenarios.

Conceptual scheme for the 5 semiquantitative scenarios used in EICAT and EICAT+ to assess negative impacts (on the left) and positive impacts (on the right) caused by a focal alien taxon (here, a shrub species) on native taxa of interest (a grass species and a bird species). Black arrows indicate the introduction and establishment of the alien taxon into a recipient ecosystem. The blue arrow indicates the reestablishment or extinction prevention of a native taxon due to an alien taxon (see also Fig 2). Shaded red figures indicate locations unoccupied by the native taxon (e.g., because of local extinctions in EICAT). Symbols were courtesy of the Integration and Application Network, University of Maryland Center for Environmental Science (ian.umces.edu/media-library).