PLANT SUCCESSION ON SICILIAN TERRACES

189 phytosociological relevés have been made in five areas of Sicily, three on volcanic substrates and two on limestones, to study plant community succession trends within abandoned terraced vineyards and cereal fields. Disturbance status and abandonment age was recorded for each sample plot. DCA of these relevés suggests that four are the most important factors driving succession, i.e. geological substrate, bioclimate, age of abandonment and disturbance. In most cases - if there are some dispersal centres near the old fields - undisturbed and less disturbed terraces evolve quite rapidly towards the local potential “climax” community. Different trends have been recorded on the areas which underwent and still undergo frequent and severe disturbance: succession is biased or even blocked in a steady state, so that grassland, garrigue, mantle or herb-dominated communities prevail. The species composition of the plant communities subject to disturbance seems to be strongly connected with the time gap between abandonment and first disturbance occurrence. The “mixed” ecological-structural-phytosociological approach here adopted to describe plant communities was quite effective to interpret abandoned terraces communities and their dynamism.