Le dinamiche del paesaggio forestale: evoluzione temporale del bosco di neoformazione sui pascoli di Corte Pogallo - Parco Nazionale della Val Grande (VB)

The aim of the present study was to investigate forest expansion, dynamics and recolonization of former crop lands, fallows and hayfields in a mountainous area (Corte Pogallo - 777 m s.l.m.) located within Val Grande National Park (VB - Italy). The site has been characterized by mountainous forests for ages, until the beginning of XXth century, when a timbering company was settled there. The whole area has been hardly deforested until the 1960, when the settlement has been completely abandoned. By matching historical (1954, 2000) aerial photographs with several test plots on the ground, the dynamic evolution of the area at the study site was analyzed using a multi-scale sampling method. To assess the stand structure, two transects were established starting from the crop fields (occurring at the valley floor) up to the beech coppice stand (occurring along the mountain slope). A mixed composition of pioneer forest species and fruit trees was found at the ecotone, while pioneer species became more and more dominant along the slope up to the beech coppice stand (the former forest margin before abandonment). Using a GIS software, pinpoint sample data and historical aerial photographs were combined and compared. Maps of land-use change revealed that forests have recolonized about 71% of the former crop area since the last fifty years (1954-2000).