Avaliação da Detecção de Desmatamento por Métodos de Sensoriamento Remoto no Estado do Tocantins, Brasil, entre 2006/2007 e 2010/2011

Abstract

Amazonia and Cerrado are the largest Brazilian biomes that have been affected by the clear-cutting of native vegetation. This study analyzed the deforestation in Tocantins state in Brazil from 2006/2007 to 2010/2011. Deforestation was measured using the DETER system (conducted by National Institute of Spatial Research, INPE) which uses data from Moderate Resolution Imaging Spectroradiometer sensor (MODIS; 250-m spatial resolution) and the results were compared with detections pointed out by visual interpretation of medium spatial resolution images (CBERS 2, Landsat 5 and Resourcesat). Out of the 4,278,372 ha area visually monitored by interpretation of images (places prevailed by the Cerrado's biome), we demarcated 842 indicatives of deforestation totaling 60,098 ha. Out of the 3,963,037 ha area monitored by the DETER system (places prevailed by the Cerrado's biome), we found 114 alerts accounting for 12,489 ha. From those detections, 20.9% were inspected in field, agreeing to deforestation as pointed out by 72.8% of the indicatives by visual interpretation and 81.5% of the DETER alerts. The remaining indicatives and alerts were commission errors by confusion with old deforestation, native vegetation, and burnt area. We estimated a real deforestations of 0.92 ha/ km² in the region of the Cerrado biome predominance (monitored by visual interpretation of images) and 0.27 ha/ km² in the area of Amazonia biome predominance (covered by the DETER monitoring). Features of each monitoring method highlighted the higher vulnerability of Cerrado in relation to Amazônia with respect to deforestation.