Recovering the landscape history behind a Mediterranean edge environment (the Congost Valley, Catalonia, 1854-2005): the importance of agroforestry systems in biological conservation.

摘要

The three main landscape dynamics now underway in Europe - urban sprawl, agricultural intensification and rural abandonment - are observed in a Catalan study area located in an edge environment between a metropolitan fringe and two natural protected sites. In this context, ecological connectivity becomes a key to host biodiversity. By applying to the available land cover maps several landscape metrics and modelling, we perform a historical landscape analysis of the changes experienced in land-use patterns and ecological processes. The results show up the relevant connectivity role played by the traditional agro-forest mosaics that linked both sides of the edge, providing a heterogeneous but continuous land matrix able to maintain high species richness. However these agro-forest mosaics are currently disappearing due to the ongoing urban sprawl and agricultural intensification in the plain, and reforestation leading to rural abandonment in the mountains. The current location of Mediterranean orchids in the study area is used to demonstrate that the results obtained through the ecological landscape assessment are not an analytical construct, but reflect the actual loss of meadows and open grazing spaces formerly created in woodland areas by a traditional multiple-use of forest and pastures now abandoned. The results show up that recovering the historical dynamics behind the current land-use patterns is a necessity for the emerging approaches to integrated biological conservation seeking a more complex and multidimensional management of sustainable cultural landscapes.