Status, processes, and drivers of soil degradation in the Mediterranean region

Soil supports life on Earth and provides several goods and services of essence for human wellbeing. Over the last century, however, intensified human activities and unsustainable management practices, along with ongoing climate change, have been degrading soils’ natural capital, pushing it towards possible critical limits for its ability to provide essential ecosystem services. Soil degradation is characterized by negative changes in soil health status that may lead to partial or total loss of productivity and overall capacity to support human societies, e.g., against increasing climate risks. Such degradation leads to environmental, social and economic losses, which may in turn trigger land abandonment and desertification. In particular, the Mediterranean region has been identified as one of the most vulnerable and severely affected European regions by soil degradation, where the actual extent and context of the problem is not yet well understood. This study provides an overview of current knowledge about the status of soil degradation and its main drivers and processes in the European Mediterranean region, based on comprehensive literature review. In the Mediterranean region, 34% of the land area is subject to ‘very high sensitivity’ or ‘high sensitivity’ to desertification, and risk of desertification applies to over more than 65% of the territory of some countries, such as Spain and Cyprus (IPCC, 2019). The major degradation processes are: (i) soil erosion, due to very high erosion rates (>2 t/ha); (ii) loss of soil organic matter, due to high mineralization rates while the region is already characterized by low or very low soil organic matter (<2%); and (iii) soil and water salinisation, due to groundwater abstraction and sea water intrusion. However, additional physical, chemical and biological degradation processes, such as soil sealing and compaction, contamination, and loss of biodiversity, are also of great concern. Some of the degradation processes, such as soil erosion, have been extensively investigated and their spatial extent is relatively well described. Other processes, however, such as soil biodiversity, are poorly investigated and have limited data availability. In general, a lack of systematic inventories of soil degradation status limits the overall knowledge base and impairs understanding of the spatial and temporal dimensions of the problem. In terms of drivers, Mediterranean soil degradation has mainly been driven by increasing population, particularly in coastal areas, and its concentration in urban areas (and consequent abandonment of rural areas), as well as by land-use changes and intensification of socio-economic activities (e.g. agriculture and tourism). Additionally, climate change, with increasing extent and severity of extreme events (droughts, floods, wildfires), may also be a key degradation driver in this region. Improved information on soil degradation status (including spatio-temporal extent and severity) and enhanced knowledge of degradation drivers, processes and socio-economic, ecological, and biodiversity impacts are needed to better support regional soil management, policy, and decision making. Science and evidence based improvements of soil resource governance and management can enhance soil resilience to regional and global changes, and support the region to achieve related Sustainable Development Goals and the Land Degradation Neutrality targets.