A Unified Classification of Alien Species Based on the Magnitude of their Environmental Impacts

摘要: Species moved by human activities beyond the limits of their native geographic ranges into areas in which they do not naturally occur (termed aliens) can cause a broad range significant changes to recipient ecosystems; however, impacts vary greatly across species and ecosystems are introduced. There is therefore critical need for standardised method evaluate, compare, eventually predict magnitudes these different impacts. Here, we propose straightforward system classifying alien according magnitude environmental impacts, based on mechanisms impact used code International Union Conservation Nature (IUCN) Global Invasive Database, presented here first time. The classification uses five semi-quantitative scenarios describing under each mechanism assign levels impact-ranging from Minimal Massive-with assignment corresponding highest level deleterious associated with any mechanisms. scheme also includes categories that Not Evaluated, have No Alien Population, or Data Deficient, assigning uncertainty all classifications. We show how this applicable at ecological complexity spatial temporal scales, embraces existing metrics. In fact, analogous already widely adopted accepted Red List approach categorising extinction risk, so could conceivably be readily integrated practices policies many regions.