The rock-dwelling vegetation of the western Stara Planina mountains in Serbia

We conducted a study focusing on the rocky habitats of the Stara Planina mountains in Serbia with the primary objectives of identifying and classifying rock communities and determining the most significant environmental factors influencing their floristic composition. Analyzing a dataset comprising 181 relevés and 151 taxa, hierarchical cluster analysis delineated 21 groups of relevés corresponding to distinct communities or associations, belonging to two different classes (<i>Asplenietea trichomanis</i> and <i>Sedo-Scleranthetea</i>), six orders (<i>Potentilletalia caulescentis</i>, <i>Violo biflorae</i>-<i>Cystopteridetalia alpinae, Tortulo-Cymbalarietalia, Asplenietalia septentrionalo-cuneifolii, Androsacetalia vandelli</i>, and <i>Sedo-Scleranthetalia</i>) and seven alliances (<i>Edraiantho graminifolii-Erysimion comati</i>, <i>Violo biflorae-Cystopteridion alpinae, Cymbalario-Asplenion, Asplenion septentrionalis, Silenion lerchenfeldianae, Saxifragion cymosae</i>, and <i>Sedo-Scleranthion</i>). Canonical correspondence analysis revealed that temperature, moisture, and altitude are the main environmental gradients shaping the dominance of particular species within these communities and distinguishing them from one another. Field observations supported these findings and highlighted additional factors, including exposure, local topography, and shading, which significantly affect temperature patterns and, consequently, the floristic composition of these communities. The findings of this study contribute to filling gaps in knowledge of the rock vegetation of the Stara Planina Mts., especially considering the sparse existing phytocoenological data, which are focused on the <i>Silenion lerchenfeldianae</i> alliance.