Fisionomia e distribuzione dei prati montani (maggenghi) in 150 anni di avanzamento spontaneo del bosco (Val di Pejo, Trentino)

Through the classification of current and historical aerial photosbetween 1973 and 2006, we analysed the evolution of size, shape and connectivity of 59 mountain meadows (maggenghi) of the Pejo district (Trentino, Northern Italy). The maggenghi are scattered patches within a forested matrix. We conducted the same analysis on an Austro-Hungarian cadastral map of 1859. The total surface covered by maggenghi was 137.4 ha in 1973, and decreased to 78.3 ha (57%) in 2006. The mean shape and connectivity index in 1973 are significantly lower than those of 2006. Within a 1-km radius around the studied patches, woodlands increased by 7% in the same time range. Among the 25 maggenghi present in 1958, 12 has been subdivided into 39 smaller fragments and 13 has been reduced in their size without any fragmentation. A general process of meadow patches evolution which included area and connectivity reduction and shape simplification has been noticed. This process is common to many other alpine landscapes. The study of these processes is fundamental for policies aimed to conservation of mountain meadows, as well as to identify the single patches deserving conservation for their current and historical landscape structure, as many studies report their significant effects on local floristic diversity.