Assessing heterogeneity from remote sensing images: The case of desertification in southern Portugal

A 10-year series of Landsat-5 Thematic Mapper images was used to test the hypothesis that increasing environmental heterogeneity at the landscape scale is evidence for desertification. The proposed methodology, based on spatiotemporal statistical analysis, was implemented for a study area in the innersouthern Alentejo region of Portugal. Major findings from the study include the increasing 'greenness' of vegetation patterns and an increasing trend towards spatial heterogeneity of both vegetation and soil variables. The former supports the global model of desertification, which proposes that feedback mechanisms stimulate the adaptation of vegetation to adverse environmental conditions by increasing biomass.