Towards a process-based evaluation of land vulnerability to soil degradation in Italy

This paper illustrates a process-based approach aimed at classifying large areas into different classes of vulnerability to Mediterranean land and soil degradation (LD and SD). A wide set of environmental and socio-economic variables was used to describe five soil degradation processes (soil erosion, salinisation, sealing, contamination, and compaction) and climate taken together as the final determinants of LD in Italy. The elementary variables contributed to generate six thematic indicators which depict the level of vulnerability of the country to each degradation process. The Multivariate Soil Degradation Vulnerability Index (MSDVI) provided an estimation of the level of land vulnerability by aggregating the six indicators. Multidimensional analyses and Geographic Information System tools were used to derive the thematic indicators and the synthetic index. Results demonstrated that in Italy, climate, soil erosion, and soil compaction/agricultural intensification represent the soil degradation processes with a potentially higher role in determining vulnerability to LD, even if with different spatial configuration patterns. On average, the most vulnerable area was insular Italy, followed by southern Italy; northern and central Italy were found less vulnerable to LD, however the MSDVI was found locally high also in northern Italy. The validation tests performed on MSDVI by field assessment and comparison with ancillary data indicated that the index is a reliable proxy of land vulnerability to soil degradation. Advantages of this approach compared to other procedures aimed at assessing LD were finally discussed.