Impact of Reforestation on Soil Quality with Emphasis in Mediterranean Mountain Habitats: A Systematic Review and Case Studies

Ecological restoration, both active and passive, comprises forest development, forest rehabilitation, and other activities that fall under the purview of eco-system services. To provide a formal framework, here we were hypothesized how do reforestation (through different forestry practices) affect the conservation of soil functionality?, that is: Reforestation/Afforestation/Forest restoration improves soil quality?; and specifically physical properties (such as structural stability, infiltration), chemical properties (such as CEC, soil organic matter content)?. For this purpose, here, we conducted a meta-analysis of numerous articles in order to compiled a large database of forest restoration studies, with emphasis on the Mediterranean region, to make robust conclusions about how it affects soil quality. Additionally, three case studies are synthetically presented concerning the short-, medium-, and long-term outcomes of forest restoration projects conducted in central and northern Spain. These cases corroborate the significant role of forest restoration in the control and enhancement of ecosystem services, particularly in relation to soil improvement, the enhancement of hydrological regulation processes within watersheds (runoff, infiltration, erosion), landscape amelioration, and the socio-economic aspects of rural environments. Ultimately, forest restoration is established as a necessary and essential practice in ecological restoration efforts to counteract the impacts of anthropogenic activities.