Land use and human impact in the Mediterranean karst of southern Italy

Human activities such as land use transformation, changes in land cover and soil surface conditions, and increasing urbanization in catchment basins may result in serious consequences for the natural environment: episodes of degradation or pollution, and deterioration in the water quality are continuously registered in many areas of the world. In addition, the human impact is also frequently at the origin of the occurrence of extreme hydrological conditions such as floods and droughts. Many natural environments are particularly susceptible to negative impacts from human activities: among these, karst is one of the most vulnerable, due to a number of geological, morphological and hydrogeological features. Karst is in fact characterized by the very limited presence, if not absence, of water flowing at the surface; water tends to quickly infiltrate underground through the network of cavities produced by karst processes. This may favour the movement of contaminants toward the water table, and the resulting deterioration in water quality. The intimate connection between surface and underground drainage, and the rapidity with which surface water may enter and percolate down through the karst rock, result in an overall extreme fragility of the karst landscape, and in a high to very high vulnerability to human impacts. In no other landscapes, likely, the effects of negative impacts, in terms of landscape modifications, or of events of pollution, may be so destructive and not recoverable. The present contribution deals with description of some examples from a typical karst Mediterranean area: the karst of Apulia, in southern Italy, where land use transformation and degradation of the natural environment have produced heavy modification in the natural landscape, leading in many cases to pollution, or to deterioration of naturalistic sites (including caves), and moving toward desertification processes as well. Assessment of the possible impacts of land use changes has become an important priority in the karst of Apulia, driven by the need to develop concepts for sustainable land management in karst environment. Apulia region is in fact mostly underlain by intensely karstified limestones, where karst processes have had a prominent role in the development of the present landscape.