Which are the drivers that influence the performance of Ligularia sibirica populations from Romania?

Abstract

Given that Ligularia sibirica, a boreal relict species in Europe, occurs in Romania in a wide range of habitat types, we assumed that under different ecological conditions, the response of phytocoenoses will be different, affecting the populations’ performance. Thus, we aimed to determine L. sibirica’s optimum conditions, through the interactions between the environmental factors and phytocoenological composition. We grouped the communities with L. sibirica according to their ecological features, with cluster analysis. The effect of interactions between the ecological factors (expressed by the Ellenberg Indicators for nitrogen availability, soil reaction, moisture, and light) and species assemblage (from the resulting clusters) on the performance of L. sibirica (assessed through its cover abundance values), was tested with general linear models. Our results show that L. sibirica’s cover abundance is influenced by the nutrient content of the substrate and by the soil reaction, not only directly but also indirectly, through the increasing competition of the ecologically specialised species (under acidification or alkalinisation conditions) or of the generalist, more productive ones (in case of eutrophication). The results also highlighted the complexity of biotic interactions from the phytocoenoses, under different ecological conditions, the same species having either a competitive or facilitative effect on L. sibirica.