Post-disturbance regrowth patterns in Mediterranean macchia
Traditionally, the southern botanists, facing much richer floras, dedicated their attention more to the disciplines of taxonomy and phytosociology. This created a detailed and extensive floristic knowledge on plant geographical distribution, poorly supported by an understanding of dynamic processes. This project was aimed to fill as much as possible of this lack of ecological approach in Mediterranean vegetation studies in Italy. The study area was located in the Campania region, southern Italy. The thesis programme was conceived as a series of investigations, starting with surveys and gradually narrowing down to specific experiments and analytical investigations. Site history is discussed as a key factor for the understanding of the regional variation of vegetation. Multivariate methods (Cluster Analysis, Principal Component Analysis) were used to analyse the vegetation composition data. They suggested that most observed changes of vegetation could reflect successional and degradation gradients rather than environmental differences. This view was supported by historical evidences of past-disturbance and dynamic processes, by study of ancient manuscripts, maps, paintings and photographs and by demographical data. The results of observations of both natural and experimental fires showed high ability to recover by vegetative sprouting and seed germination. Most fires were followed by 100&'37 survival with few exceptions in the case of the dry winter 1989 and of very hot fires. In these cases, Erica arborea was the most sensitive species. In contrast to fire, cutting depressed regrowth at one of the study sites located on most exposed and dry conditions. Recolonization after complete vegetation removal showed a different succession with an initial dominance of Dittrichia viscosa, later suppressed by Cistus spp. and Ampelodesmos mauritanicus. E.arborea did not recolonize after this kind of disturbance.