A landscape approach for detecting and assessing changes in areas prone to desertification by means of remote sensing and GIS

Land degradation and desertification processes represent a serious problem in many Italian regions, as in the north-western part of Sardinia (Nurra region) where urbanization overgrazing and fires have induced environmental degradation and rapid land-use change, thus altering entire landscapes. In semi-arid and arid environments, in particular, where fragile ecosystems are dominant, land cover and landscape change often reflects the most significant impact on the environment due to human activity. In the present research, we tested the concepts of a landscape approach in areas prone to desertification, where this kind of investigation has not experimented on up until now. Up to now landscape ecology has been rarely combined with the issue of desertification, in particular in the Mediterranean region. By means of remote sensing, Geographical Information System and the software FRAGSTAT, three Landsat MSS and TM images, covering the period between 1972 and 2000, werw classified and a stepwise indicator approach was adopted in order to detect the location, the direction, the magnitude of the changes and the spatio-temporal dynamic of landascape in a area prone to desertification. Relevant processes affecting the study area were therefore identified, as in the municipalities of Stintino and Porto Torres, where forest fragmentation, expansion of agricolture and urban sprawl can be considered among the main degradation factors and causes of the sensitivity to desertification. The results of the study that actually achieved monitoring of land cover and landscape change over time, have made an important step towards warning the authorities of the circumstances of the past and current landscape changes and their consequences.