THE VEGETATION OF CALCAREOUS SNOW-VALLEYS, TALUS SLOPES AND PEBBLY RIVER-BEDS IN FRIULI (NE ITALY). The pioneer vegetation of the calcareous snow-valleys (Arabidion caeruleae), talus slopes (Audrosacion alpinae, Thlaspion rotundifolii, Petasition paradoxi, Stipion calamagrostis) and pebbly river-beds (Salicion incanae, Dauco--Melilotion) was studied in Friuli (Northeastern Italy).
16 coenoses have been defined also on the ground of the numerical classification of the vegetation data: Salicetum retuso-reticulatae, Sieversio-Oxyrietum digynae, Hieracietwn intybacei (new association), Papaveretum rhaetici, Papaveri julici-Thlaspietum rotundifolii, Leontodontetum montani, Dryopteridetum villarii, Moehringio-Gymnocarpietwn robertiani, Festucetum laxae, Athamanto cretensis-Trisetetum argentei (new association), Adenostyli glabrae-Heracleetum polliniani, Stipetum calamagrostis, Leontodonto beriniiChondrilletum, Petasites paradoxus-phytocoenon, Epilobio-Scrophularietum caninae and Calamngrostis pseudophragmites-phytocoenon. The floristic composition, the syntaxonomic relations, the synecology and synchorology, the chorological and life-forms spectra for each coenosis are discussed. The last chapter deals with the floristic pollution and anthropization of the most important rivers of the investigated region.
