Ecohydrological-Based Forest Management in Semi-arid Climate

The role of forests on the provision and regulation of non-marketed ecosystem services is well known (Thorsen et al. 2014). This is especially important in areas like the Mediterranean, where protective forests play a major role against soil erosion and degradation, landscape quality and stabilization of the hydrological cycle. Socio-economic and cultural changes affecting rural society from the 1960s have produced a demographic decline, and with it, an abandonment of rural activities, leading to an expansion and densification of forest and scrub. Forest encroachment may decrease the streamflow from upper catchments (Gallart and Llorens 2004); this study reports a decrease in average annual flow of major Spanish rivers between 37 and 59%, partly explained by the densification of upstream forests, and increasing interception loss. Moreover, some Mediterranean basins (e.g. Segura and Júcar in Spain) present very serious problems of water scarcity, because of a combination of low/irregular rainfall and high rates of evapotranspiration, that has resulted in overuse of groundwater resources (Estrela et al. 2000a, b). These problems may even endanger urban water supply (approx. 15% of the total water supply in Spain). In addition, the Mediterranean region is already suffering some significant impacts of the climate change, such as longer dry seasons, or lower soil moisture content (Giorgi and Lionello 2008; García-Ruíz et al. 2011). All these issues have raised concern about the importance of forests and water interactions in the Mediterranean (Birot et al. 2011).