Spatio-temporal patterns of satellite images for environmental analysis

Spatial heterogeneity is assumed as an environmental system property, essential to understand either the environmental gradients and the systems functioning. Heterogeneity refers to some pattern of variation, both in space and time, but within some range. Usually the pattern and the range is physically adequate for the ecosystem it occurs, defining the system resiliency. A change of spatial heterogeneity can he viewed as an indicator of environmental changes, and a clue of some process. The goal of this paper is to test the usefulness of spatial analysis methodologies to capture spatio-temporal heterogeneity environmental gradients. A set of ten-year period of Landsat5-TM images are explored for soil properties and a local analysis of variances are performed to assess spatial patterns. This work is included in a wider research goal, referred to desertification assessment in southern Portugal, and thus previous results concerning vegetation patterns are integrated. Main results refer that there has been an increase of spatial heterogeneity patterns, both referred to soil anti vegetation, which means the ecosystem is evolving to a qualitative different stage of development. According to field works [11], the increase of spatial heterogeneity patterns is usually associated with a desertification process.