Assessment of forest degradation in Brazilian Amazon due to selective logging and fires using time series of fraction images derived from Landsat ETM+ images

摘要

A method has been developed to identify and map areas of forest degradation caused by either selective logging or fires in tropical humid ecosystems. Our study area is located in the Mato Grosso state of Brazil, in a region known as 'Deforestation Arc'. Eight consecutive Landsat Enhanced Thematic Mapper Plus (ETM+) images were available over this study area during the dry season of 2002 (from June to October). The proposed method is based on multi-temporal image segmentation and classification of a data set of soil and shade fraction images derived from Landsat ETM+ imagery. Areas of selectively logged forest are identified and mapped from the soil fraction images, whereas burned forest areas are identified and mapped from the shade fraction images combined with a map of deforestation happening during 2002. The main benefit of this approach is the capability to discriminate selectively logged forest from burned forest, which is a very important issue for estimating carbon emissions from forest degradation.