By Irena Axmanová, Veronika Kalusová, Jiří Danihelka, Jürgen Dengler, Jan Pergl, Petr Pyšek, Martin Večeřa, Fabio Attorre, Idoia Biurrun, Steffen Boch, Timo Conradi, Rosario G. Gavilán, Borja Jiménez-Alfaro, Ilona Knollová, Anna Kuzemko, Jonathan Lenoir, Artem Leostrin, Jana Medvecká, Jesper Erenskjold Moeslund, Dragica Obratov-Petkovic, Jens-Christian Svenning, Ioannis Tsiripidis, Kiril Vassilev & Milan Chytrý
Human activities enabled the spread of many species outside their natural ranges. These alien plants may successfully establish in new regions, some of them growing even better than native plants and changing the original vegetation. However, their numbers and impact differ among regions and habitats. In our study, we focused on European grasslands and used the most comprehensive dataset of vegetation plots available – European Vegetation Archive (http://euroveg.org/eva-database). We wanted to list the most widespread alien species and to compare differences in the level of invasion among countries and habitats.
We found that approximately 6.5% (536 species) of all plants were aliens (non-native plants introduced to the given country after 1500 AD, so-called neophytes). Most of the aliens were relatively rare in grasslands and not specialized to any finer habitat type. Many of them were short-lived species that produce many seeds and take advantage of disturbed patches, such as Erigeron annuus and Erigeron canadensis.
We found more invaded vegetation in the northern part of Europe (Fennoscandia, the Baltic countries and Poland), where there were relatively higher numbers of aliens from other continents, as well as alien species coming from southern Europe. When considering only aliens from outside Europe, the most invaded was the Pannonian region, where the high abundance of open habitats and summer-warm climate are suitable for establishment and persistence of many alien plant species.
In general, if we compare our findings with lowland forests, riparian or human-made habitats (fields, vegetation in the cities and their surroundings), European grasslands have lower invasion levels. However, some grassland types, such as sandy grasslands or wet lowland grasslands, are more vulnerable and more easily invaded by alien plants than others. In contrast, almost free of aliens are grasslands at high elevations, where the environment is harsh and human impact low. Some grassland types seem to be prone to invasions only when traditional management (grazing or mowing) is abandoned.
This is a plain language summary for the paper of Axmanová et al. published in the Journal of Vegetation Science (https://doi.org/10.1111/jvs.12994). The post was prepared by Irena Axmanová, Milan Chytrý and Veronika Kalusová.