Understanding what species characteristics allow some alien plants to become invasive while others fail is critical to our understanding of community assembly processes. While many characteristics have been shown to predict plant invasiveness, the importance of plant-soil feedback (PSF) in invasions has been difficult to assess since individual studies include only a few species and use disparate methodology. We studied PSF of 68 invasive and non-invasive alien species in a single two-phase common garden experiment, and compared the relative importance of PSF, residence time, phylogenetic novelty and plant traits for plant invasiveness. Additionally, we explored relationships between PSF, residence time and phylogenetic novelty. PSF for seedling establishment, but not for biomass, was a significant predictor of invasive status, with invasive species having more positive PSF than non-invasive species. Its explanatory power was, however, much lower than that of specific leaf area, height, and residence time. Phylogenetically novel species experienced less negative PSF than species with native congeners, suggesting they benefit more from enemy release. PSF of non-invasive species, contrary to that of invasive species, was becoming more negative with increasing residence time. We demonstrated that PSF for seedling establishment plays a role in predicting plant invasiveness and is a better predictor than more commonly studied PSF for plant biomass. Other species traits, such as specific leaf area, however, predict plant invasiveness much better than the PSF.

Intraspecific plant-soil feedback of 68 alien species differing in their invasive status in the Czech Republic was assessed using a two phase garden experiment. We compared plant performance (seedling establishment, biomass) of the plants in the second experimental phase when grown in self-conditioned soil and in control (unconditioned) soil. Plant-soil feedback index was calculated as ln(x/s) where x is performance of each individual plant when grown in the conditioned soil and s is performance of a plant grown in a paired control pot. For each species, we also measured specific leaf area and we gathered data on other plant traits used for explaining plant invasiveness as well as on species comonness in the Czech Republic, their phylogenetic relatedness to native Czech flora and residence time in the Czech Republic from published literature and databases. We used the data for assessing the importance of plant-soil feedback for plant invasiveness and for determining the relationships between plant-soil feedback, phylogenetic relatedness and residence time.  

For more details on the experimental design and data collection please refer to Aldorfová et al. (2020),10.1111/oik.07186.