Background and aims Although plant-soil feedback has been suggested as a mechanism that drives the success of invasive plants, studies that investigate differences in the intensity of plant-soil feedback among native and invasive populations of the same species are still lacking. However, such knowledge is important because it can provide an understanding of the mechanisms responsible for the spread of a species. Rorippa austriaca is a potentially invasive species -a successful range expander in Europe.Methods We compared the plant-soil feedback of R. austriaca in populations from its native and invasive range. We explored both intraspecific feedback as well as feedback on a co-occurring grass species. Results Our results revealed a strong negative feedback effect as a consequence of soil conditioning by R. austriaca from the native range. On the contrary, a negative feedback effect was not observed for invasive R. austriaca. Interestingly, R. austriaca from the invasive range had a higher biomass than native R. austriaca. Conclusion Our results might be explained by pathogen accumulation and soil modification by native R. austriaca, which had strong intra-and interspecific effects that seemed to be lost in the invasive R. austriaca. The loss of negative intraspecific plantsoil feedback and the increased growth of the invasive population may contribute to its successful range expansion. In spite of its increased growth, the co-occurring grass species is expected to successfully coexist with the invasive R. austriaca.

We found that Salvia nubicola distributed along a broad altitudinal gradient developed a range of defence strategies against insect herbivores. The strategies, however, do not seem to be used simultaneously in all populations even though most of them are correlated with the altitudinal gradient along which herbivore pressure is decreasing. Our study thus shows the importance of simultaneous study of different defence strategies since understanding trade-offs among them could be necessary for detecting the mechanisms by which plants are able to cope with changes in plant-herbivore interactions as a consequence of future climate change.

The aim of this study was to estimate genetic diversity and assess its importance for plant fitness in a species belonging to the most endangered species in Europe, Dracocephalum austriacum L., and to select the most valuable populations for conservation of genetic diversity within the species in the studied regions. We analyzed allozyme variation of 12 populations in three distinct regions (Czech Karst, Moravia and Slovak Karst) in Central Europe. The results showed high genetic diversity within populations (80.14%) and relatively low differentiation among populations within regions (9.42%) and between regions (10.45%). Seed production was significantly higher in larger, genetically more diverse and less inbred populations. The results suggest that genetic diversity has important effect on seed production in this species and thus can be expected to have strong direct consequences for plant fitness and vitality of the whole populations. They also show large variation in genetic diversity between populations and indicate which populations should get a priority in attempts to conserve all the genetic diversity within the region.