Dinamiche naturali in formazioni forestali a prevalenza di leccio nel Parco Regionale della Maremma

Abstract

Mediterranean sclerophyllous forests are coenoses worthy of great care because of their inherent bio-ecological value. The suspension of harvesting following the crisis of fuel wood market ruled the evolutive pattern of maquis over the last decades. In this phase, site quality seems to be the major driver of the holm oak-dominated forest recovery as well as of the lasting permanence of the sclerophyllous shrub forest. In this connection, stand dynamics has been monitored in three plots located in the strictly protected area of the “Parco Regionale della Maremma” (Grosseto - Tuscany), where natural evolution is in progress since at least five decades. The monitored stands are representative of different evolutive phases from the holm oak-dominated coppices to the typical maquis, as a function of the original stand structure and composition but also of the intensity and length of the applied coppice management system. The analysis was carried out by permanent transects; two inventories were undertaken in 1991 and 2006 to evaluate both compositional and structural variability and the dynamics in progress. Results at now highlight the role played by the residual site quality and specific composition in driving the evolutive pattern of tree species community. Under the absence of any silvicultural practice and better site conditions, the progress and specific incidence of regular mortality and the related aboveground biomass redistribution, supported the vegetation of holm oak and the other subsidiary species typical of more mature stages. The overall forest dynamics seemed anyway to proceed slowly and resulted in a steady physiognomy over a long time since the suspension of the historical disturbance made of repeated harvesting on short rotations.