Spatial-temporal variation of the indexes of vegetación and evapottranspiración in areas of caatinga

Abstract

Caatinga vegetation comprises about 80% of the Northeast region and 11% of the national territory. This biome is predominantly made up of plant species of arboreal and shrub size, which guarantees a complex heterogeneity in the vegetation cover. Understanding the biophysical processes associated with this variation is of paramount importance for understanding ecosystem processes. Therefore, the objective of this work was to evaluate the spatio-temporal variation of vegetative indices and evapotranspiration in fragments of Caatinga with different phytophysiognomies, located in the municipality of Bom Jesus, Piauí. The images used came from the OLI and TIRS sensors of the Landsat 8 satellite, for the areas where there was the identification of three fragments of the Caatinga, Caatinga tree (CAbo), Caatinga tree-shrub (CAb) and Caatinga shrub (CAbu). Through the processing of the SEBAL algorithm, the NDVI, SAVI and IAF vegetation indices and biophysical indices of Surface Temperature (Ts) and Evapotranspiration (ETr) were obtained. It was observed that in relation to the average vegetation indexes, the fragments showed a distinction between vegetation cover and density, being associated with variations of Ts and ETr, in which the occurrence of lower temperatures and higher ETr was noteworthy in areas with higher densities of vegetables. Thus, the relevance of the vegetation cover for the maintenance of the biophysical processes on the terrestrial surface is emphasized.