Reforestation dynamics after land abandonment: a trajectory analysis in Mediterranean mountain landscapes

Reforestation after land abandonment across Mediterranean mountains, together with the related landscape pattern dynamics and its possible impacts on the natural flora and fauna are issues that need further research efforts. This research, based on multi-temporal land cover maps derived from remotely sensed data (1987, 2003, 2016) of the Central Apennines, sets out to (i) quantify land cover changes and (ii) explore forest re-growth accounting for the interdependencies between forest gain and spatial configuration through trajectory analyses. Landscape change was assessed by transition matrix. Forest composition and configuration over time were analyzed by trajectory analysis based on random sampling techniques. This approach, implemented here for the first time for analyzing forest re-growth, allows us to explore the relationship between forest gain (the percentage of landscape covered by forests) and changes in spatial pattern (patch density, edge density, and mean patch area). An increase in forest cover over the past 30 years underlined the intense process of natural re-colonization, which started after World War II, at the expense of the typical heterogeneity of Mediterranean cultural landscapes. The change in the spatial pattern of forested areas highlighted a significant transformation which is related to two processes: the centrifugal development of existing patches and the establishment of new nuclei. The trajectory analysis highlighted non-linear relationships between forest gain and spatial pattern, offering the basis envisage of their effects on biodiversity. Conservation-oriented management of Mediterranean mountain forests must acknowledge both the role of natural succession in generating complex mosaics and the importance of maintaining forest patches of different dimensions and configuration.