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Early Identification of Land Degradation Hotspots in Complex Bio-Geographic Regions (RS)

The detrimental impacts of these processes on land resources, which are widely recognized as environmental problems of global concern become really dramatic in arid, semi-arid and dry sub-humid regions (drylands), where land degradation is more properly defined as desertification. The development of low-cost and relatively simple tools to identify emerging land degradation across complex regions is fundamental to plan monitoring and intervention strategies.

The authors propose a procedure that integrates multi-spectral satellite observations and air temperature data to detect areas where the current status of local vegetation and climate shows evident departures from the mean conditions of the investigated region. The procedure was tested in Basilicata (Italy), which is a typical bio-geographic example of vulnerable Mediterranean landscape. They grouped Landsat TM/ETM+ NDVI and air temperature (T) data by vegetation cover type to estimate the statistical distributions of the departures of NDVI and T from the respective land cover class means. The pixels characterized by contextual left tail NDVI values and right tail T values that persisted in time (2002–2006) were classified as critical to land degradation.

According to the results, most of the critical areas (88.6%) corresponded to forests affected by erosion and to riparian buffers that are shaped by fragmentation, as confirmed by aerial and in-situ surveys. The procedure enables cost-effective screenings of complex areas able to identify raising hotspots that require urgent and deeper investigations.