Insights into global change effects on a Mediterranean rural landscape with badlands: a remote sensing approach on climate and land cover changes

Over the past decades, the combined effects of climate, in terms of thermo-pluviometric variability, and land-cover transformations have profoundly reshaped Mediterranean rural landscapes, altering their ecological balance and geomorphological stability. These pressures are particularly critical in badland environments, fragile erosional systems marked by steep slopes, limited vegetation, and dense networks of gullies and mass-wasting features, often associated with rural landscapes. This study investigates four decades (1984–2023) of vegetation dynamics within the Orcia River catchment in Tuscany (Italy), a UNESCO World Heritage Site containing representative sub-humid badlands, with the aim of explaining these dynamics in relation to climate variability and land-use changes. Monthly Normalized Difference Vegetation Index (NDVI) time series derived from Landsat imagery were analyzed together with MODIS Land Surface Temperature (LST), Global Precipitation Measurement (GPM) data, and ground-based meteorological records. Regional Land Use and Land Cover (LULC) maps were analyzed to evaluate land-cover transitions. Long-term vegetation and climate trends were assessed using the Mann–Kendall test and Sen's slope estimator on NDVI pixels filtered using the Pixel Quality Assessment (PQA) band and on climatic satellite and ground-based datasets (2004–2023). Results revealed a steady and statistically significant greening trend across the study area since 1984, with most pixels showing NDVI increases of about 0.005 units per year. Vegetation changes were mostly insignificant or slightly negative during 1984–2003, whereas a more pronounced increase occurred after 2004 (0.005–0.010 units yr−1, up to 0.015 along river corridors). Satellite and ground-based meteorological station data showed a warming trend, particularly in minimum temperatures, whereas precipitation remained generally stable. About 42% of the area underwent land-cover change, primarily due to forest expansion and a reduction in grazing and sparsely vegetated areas, mostly linked to the badlands surface. NDVI–LULC intersection analyses showed that most NDVI variations coincided with land-use transitions, while NDVI increases in stable areas suggest management-driven change in vegetation cover. This greening process seems to be enhanced by the registered warming trend, as suggested by the positive correlation between MODIS-NDVI and MODIS-LST values within the southern forested region. Our findings demonstrate the synergistic influence of climate warming and land-cover change on Mediterranean landscapes. The general greening process, which leads to a reduction of badland surfaces, appears to be driven by more favourable climate conditions, which enhance vegetation vigour, and by the abandonment of traditional agricultural practices, allowing natural vegetation recovery.