A multi-scale and multi-disciplinary approach to monitor landscape dynamics: a case study in the Catalan pre-Pyrenees (Spain)

(un facteur d'impact)ACLInternational audienceA multi-scale and multi-disciplinary method was tested in the Catalan pre-Pyrenees in order to understand the relationship between landscape change, landscape processes, and ecological and social characteristics of landscapes. The three scales, and their corresponding methods, help us understand the processes of landscape change: on a general scale, a standardisation due to forest spread; on a detailed scale, a fragmentation of non-forest habitats; and on a local scale, the regeneration and scattering of woody species. Major landscape alterations have been observed through remotely sensed data. Closed forest area grew 140% at the expense of non-forest habitats such as pastures (-75%) and cultivated lands (-95%) during the past 50 years. Ecological metrics show a landscape standardisation (SHDI divided by 3) and a fragmentation of farmed landscapes. These changes, following a spatial pattern based on topography, explain the dynamic of the woody species in residual pastures, despite the persistence of cattle grazing as observed during field surveys. Yet, the forest, which constitutes the matrix of landscape, is not stable because of competition between species. The landscape change is related to the decline of the population (divided by 4.5 during the past 50 years) and the agricultural activities (number of farms divided by 2 or 3 during the past 20 years), and the favourable mild climate. The sustainable development of this territory should make the objectives of conservation, biodiversity and landscape protection and the preservation of their Mediterranean features compatible, and support agricultural activities that will contribute to this biological diversity and cultural identity