Coexistence and niche differentiation at large spatial scale in a West-European softwater plant community

There is growing evidence that species are able to coexist in communities through niche separation, and that consistent community structuring can take place at the biogeographical scale, as the same biotic interactions can determine species' fate at large scales. In this study, we document niche differentiation at a larger scale within a specific plant community of softwater lakes in Western Europe. Five species were selected for their relative frequency and wide geographical distribution within the dataset that we collected. Their niches were modelled both from presence-absence data and from ordinal abundance data, using mixed regression techniques (generalized linear mixed models and proportional odds mixed models, respectively). The modelled realized niches differed among the species on the West-European scale, although strict separation was not shown and geographical coverage is not complete. Plant strategy characterization of the species supported the assumption that functional traits underpin the niche differentiation among the species through fitness trade-offs. Mechanistic experimental research at a range of spatial scales is needed to test the importance of different community structuring mechanisms at the biogeographical scale, such as biotic interactions and environmental filtering.