Phytogeographic and syntaxonomic diversity of wall vegetation (<i>Cymbalario-Parietarietea diffusae</i>) in southeastern Europe

Walls represent globally distributed, locally extensive, artificial ecosystems. Wall vegetation is still poorly known in the Mediterranean and Temperate regions of southeastern Europe. The aim of this study is to classify and describe chasmophytic vegetation of walls, covering southeastern Europe from Slovenia to North Macedonia. From a total 463 phytosociological relevés, we identify and describe 12 distinct species – poor to moderately rich vegetation units using TWINSPAN evaluated by NMDS, and indicator values. The vegetation units are included within three alliances from two macroclimate regions: (1) vegetation of cool-temperate Europe of the <i>Cymbalario-Asplenion</i> alliance, and (2) Mediterranean vegetation of the <i>Galio valantiae-Parietarion judaicae</i> and <i>Artemisio arborescentis-Capparidion spinosae</i> alliances. The southernmost limit of the <i>Cymbalario-Asplenion</i> was determined in Central Bosnia. The presence of the <i>Artemisio arborescentis-Capparidion spinosae</i> in the eastern Adriatic is highlighted.