Evaluation of biophysical indices from TM Landsat 5 images in heterogeneous landscape in Southwestern Amazon

The southwest area of the Brazilian Amazon is composed of a landscape mosaic with transition grasslands and tropical rain forest. The basin of the Puruzinho River, located in the "Arc of Deforestation" in the Purus-Madeira interfluve, has undergone changes in land use and land cover. The objective of this study was to evaluate the spatial variation of biophysical indices of a heterogeneous landscape in the Basin of Puruzinho River. The normalized difference vegetation index (NDVI), leaf area index (LAI), surface temperature, surface albedo and surface net radiation (Rn) were estimated by SEBAL (Surface Energy Balance Algorithm for Land) from TM Landsat 5 images, and analyzed on areas of dense forest, grasslands, deforested area and urban area of Humaitá-AM. All biophysical indices were significantly different considering the land use and land cover. The biophysical indices showed an opposite pattern between the urban area and the dense forest, with lower NDVI, IAF and net radiation and higher surface temperature and surface albedo in the urban area. Therefore, the variables estimated by SEBAL were adequate to assess the effect of land use changes on the estimated variables and to distinguish disturbed areas from natural areas.

Amazonia; deforestation; radiation balance; spatial analysis