Vegetation patterns, functional traits and invasion dynamics across railway microhabitats in Slovenia

Abstract Purpose Railways are anthropogenic habitats shaped by various disturbances and management practices. Consequently, many studies report on significant plant diversity and vegetation heterogeneity in railway environments. We present results of the first systematic study of railway flora in Slovenia, focusing on microecological differentiation of railway zones and the role of railways as corridors for non-native species. Methods At 92 locations across 15 segments of the Slovenian railway network, we conducted floristic sampling by transect method, studying four distinctive railway zones – Sleeper Zone (SZ), Ballast Shoulder (BS), Ballast Toe (BT) and Intertrack Area (IA) separately. We compared taxonomic and functional diversity, ecological indicator values and vegetation cover among zones using generalised linear mixed models and multivariate analyses. Results We recorded 312 taxa from 67 families. Zone type significantly influenced species richness, vegetation cover and community composition. The BT supported the highest richness and densest vegetation, while the SZ and IA harboured thermophilous, heliophytic annuals adapted to the most extreme conditions. Hemicryptophytes and competitive species prevailed in outer zones; therophytes and ruderal species dominated inner zones. Ecological indicator values confirmed clear gradients of light, temperature and moisture across zones. Non-native species (13% of flora) were nearly ubiquitous, with invasive aliens present at 99% of sites, underscoring railways as invasion corridors. Conclusions Our results confirm the considerable diversity of Slovenian railway flora, microecological specificity of railway zones, and the importance of railways in the spread of non-native species – findings, which have previously been overlooked in Slovenia.