Urban sprawl and desertification risk: unraveling the latent nexus in a mediterranean country

The Mediterranean region is exposed to desertification risk because of the joint impact of soil degradation, land-use change and global warming, although the individual role of such drivers has been occasionally investigated. The present study clarifies the spatial linkage between desertification risk and urbanization, intended as a pervasive form of landscape transformation in Southern Europe, by analyzing trends over time in the Environmentally Sensitive Area Index (1960–2010) at different settlement densities in Italy. Seven density classes, representing a vast range of local contexts from pristine, natural sites to peri-urban conditions with moderate (or high) human pressure, were considered. While land surface with medium-high settlement density increased between 1960 and 2010, reflecting semi-dense urban growth (1960–1990) and settlement sprawl (1990–2010), the spatial distribution and extent of land sensitive to desertification in Italy followed more complex dynamics over both time and space. Divergences in the level of desertification risk along the settlement density gradient increased markedly in 1990 and 2010. The highest level of risk was observed for land with intermediate settlement density, representing economically dynamic rural contexts with high (and possibly increasing) human pressure. Despite some exceptions, a lower level of risk was observed in urban and peri-urban areas with denser settlements. The spatially asymmetric increase in the level of desertification risk contributed to alter the polarization in affected and non-affected areas characteristic of early-1960s Italy. A rising impact of settlement density on desertification risk has been recorded in more recent years. Based on the empirical results of this study, National Action Plans to combat desertification in Mediterranean Europe are definitely required to incorporate specific measures of urban containment and mitigation of the negative effect of sprawl on land degradation at a local scale.