The bryophyte epiphytic vegetation in the part of the Trieste Karst comprised within the Italian national borders has been studied with the Braun-Blanquet method. The study region is mainly covered with Ostrya carpinifolia, Fraxinus ornus and Quercus pubescens coppices and has a submediterranean-subatlantic climate. Four main vegetation types could be distinguished by numerical classification of the relevés: Tortuletum laevipilae, Leucodontetum sciuroidis, Hypnum cupressiforme-community and Neckero-Anomodontetum viticulosi. The ecological requirements of these communities have been defined by measurement of abiotic parameters and by indirect gradient analysis performed through ordination of the relevés. It could be demonstrated that the main ecological factor conditioning the distribution of the bryophyte epiphytic synusiae in the study region is bark moisture which is directly controlled by light intensity.
