Dutch elm disease, ash dieback, Himalayan balsam and giant hogweed — all these invasive species have significant impacts on forest ecosystems. Prioritising non-native species according to the extent of their environmental impacts is becoming increasingly important for the management of protected areas.

In a study published in October 2021 in the open-access journal NeoBiota, experts from central and south-eastern Europe assessed fungal, plant and insect species using the EICAT framework and determined their influence on the threatened riparian forests of the Mur-Drava-Danube Biosphere Reserve. The IUCN EICAT standard (Environmental Impact Classification of Alien Taxa), which deals with the environmental impacts of invasive species, serves a similar function to the IUCN Red List, where threatened species are classified. Management measures were subsequently ranked by priority.

Native species under pressure

Together with local experts, a list of 198 non-native species (115 plants, 45 insects and 38 fungi) was compiled, whose populations have been recorded in south-eastern European forest ecosystems. For 114 species, the experts found reports of impacts. Eleven of these species caused the local extinction of a native species, while 35 led to population decline. "Fungi had by far the strongest impacts, mostly through competition and parasitism," explains biodiversity expert Katharina Lapin from the Federal Research Centre for Forests, Vienna.

This study is the first application of EICAT to all known non-native species across multiple taxonomic groups in a protected area. The impact ranking made it possible to identify taxa causing high impacts and to prioritise species for management in protected areas according to the extent of their impacts. The study's authors recommend systematically surveying non-native species in order to identify knowledge gaps and set priorities for their management with regard to spatiotemporal trends in impact magnitude.

Further information

Original article "Comparing environmental impacts of alien plants, insects and pathogens in protected riparian forests": NeoBiota 69: 1-28 (2021). https://doi.org/10.3897/neobiota.69.71651

Environmental Impact Classification for Alien Taxa (EICAT): https://www.iucn.org/theme/species/our-work/invasive-species/eicat

Enquiries: Christian Lackner, Federal Research Centre for Forests, 0664 8412702, christian.lackner@bfw.gv.at