Contrasting diversity patterns of native and alien species across multiple taxa in Central European river corridors

River corridors are among the most important natural pathways for invasive species to spread into landscapes. Nevertheless, the ecological processes underlying invasions of riparian habitats are poorly understood for many taxonomic groups. We sampled bryophytes, vascular plants, and molluscs along three West Carpathian rivers (Central Europe) to identify spatial trends and drivers of native and alien species diversity across multiple taxa. Generalised additive models revealed decreasing downstream diversity patterns across all studied rivers and taxonomic groups. In contrast, alien diversity showed the opposite trend, displaying a high degree of idiosyncrasy among the rivers. Random forest analysis revealed that climate-induced variables (altitude and related temperature) played a more pronounced role in the diversity of alien species than in the diversity of native species. The diversity of native species was more influenced by local land use and habitat alternations (molluscs) or by source-to-mouth river interactions along the longitudinal gradient (plants). Dispersal limitation and temperature constrain alien species distributions along river corridors, while a multitude of natural and anthropic influences drive native species diversity. The climate-driven distribution of alien plants and molluscs suggests future altitudinal and longitudinal shifts in non-native species along river corridors, which will be exacerbated by ongoing climate warming and associated environmental changes.