Horizon-scanning for Invasive Non-native Plants in Great Britain

In May 2008, the GB Strategy for Invasive Non-Native Species (INNS) recognised the need to prevent the introduction and spread of potentially invasive non-native species. Determining which species will become invasive is notoriously difficult, the best predictor being evidence of invasiveness elsewhere. To assist in prioritising and targeting of prevention work, Natural England sought a horizon-scanning exercise to identify non-native plants that are most likely to become invasive in Great Britain in the future.

The report lists potential, new, invasive, non-native plant species in Great Britain using existing information on INNS. These might be species that are already here but are not established, or species that are yet to arrive. Of 599 non-native plants assessed. 92 are ranked as critical (in terms of requiring more-detailed risk assessment as a priority), 55 as urgent, 72 as moderate risk and 380 as low risk (requiring no further assessment at present. Complete screening scores for all plants assessed are provided in Appendix1 (see the link on the Natural England website given on p.24).

One of the conclusions is that the need for a resource-efficient risk assessment with proven high predictive power in screening large numbers of non-native aquatic and terrestrial plants remains unabated. It is hoped that the results of this project will facilitate the development of such a system. It is envisaged that the report will stimulate debate and help to inform the targeting of resources.