Ecology and niche assembly of Campanula tommasiniana, a narrow endemic of Mt Učka (Liburnian karst, north-western Adriatic)

Campanula tommasiniana is a typical chasmophyte occupying calcareous rock crevices and cracks along a wide range of ecological gradients, demonstrating a high degree of ecological plasticity and stress tolerance with regards to abiotic factors. Generally, three ecologically and floristically distinct groups of stands were recognized and typified according to a sigmatistic approach: (a) Seslerio juncifoliae-Campanuletum tommasinianae ass. nov., with stands occupying higher elevated sites fully exposed to sun and strong winds; (b) Seslerio autumnalis-Campanuletum tommasinianae ass. nov., representing stands predominantly developed within thermophytic beech stands, semi- to fully- shaded by the tree canopy; (c) Cystopteri fragilis-Campanuletum tommasinianae, sciophytic, stands adapted to moisture and coldwith high frequency and coverage of bryophytes. Results of DCA analyses using a unimodal model suggest that Campanula tommasiniana is primarily a plant of open and exposed sites of higher elevation despite being most frequently found in rock crevices within thermophytic and altimontane beech forests