Spatial Vegetation Variation Patterns in Southern Italy as Detected by AVHRR and MODIS Observations

Spatial variations in Southern Italy vegetation production were analyzed between 1995 and 2005. The analysis was carried out using Normalized Difference Vegetation Index (NDVI) time series derived from NOAA AVHRR images, retrieved from DLR/EOWEB archives and corrected using an ad-hoc method. The correction method exploits more accurate MODIS NDVI maps which only became available on NASA archives in the last three years. The changes occurred is "biomass production" in the last decade were analyzed by only considering vegetation behaviour during the growing seasons. This approach improves the results by excluding from the analysis the winter months, during which vegetation exhibits a stationary behaviour, NDVI data are less significant and the biomass production is poor. The correlation between vegetation relative change patterns and terrain altitude, as derived from SRTM topographic data, was also investigated. This analysis shows the presence of different changing patterns such as: i) a vegetation production degradation in several areas with variations up to -1% ; ii) a systematic vegetation production increase over the Apennines up to 6% . These results, in agreement with temperature trends for the winter months in the last years highlight climate change processes occurring in the Mediterranean areas: temperature mitigation facilitates "robust" vegetation, like conifer stands, deciduous stands and in general Mediterranean maquis, i.e, the kind of vegetation which can be found in upland and mountain zones. On the contrary, particularly in the plains, plant foliation in the autumn-winter period is strongly affected by sudden low temperature peaks and by human activities.