Relationships between burned area, forest cover loss, and land cover change in the Brazilian Amazon based on satellite data

[摘要] Fires are used as a tool in the deforestation process. Yet, the relationshipbetween fire and deforestation may vary temporally and spatially dependingon the type of deforestation and climatic conditions. This study evaluatesspatiotemporal dynamics of deforestation and fire represented by burned areaover the 2002–2012 period in the Brazilian Legal Amazon. As a first step,we compared newly available Landsat-based maps of gross forest cover lossfrom the Global Forest Change (GFC) project with maps of deforestationextent from the Amazon Deforestation Monitoring Project (PRODES) produced bythe Brazilian National Institute for Space Research (INPE). As a secondstep, we rescaled the Landsat-based data to the 500 m resolution of theModerate Resolution Imaging Spectroradiometer (MODIS) burned area data(MCD64A1) and stratified this using MODIS land cover data to study the roleof burned area in forest cover loss and deforestation. We found that whileGFC forest cover loss and PRODES deforestation generally agreed on spatialand temporal dynamics, there were several key differences between thedata sets. Both showed a decrease in the extent of forest cover loss ordeforestation after 2004, but the drop was larger and more continuous inPRODES than in GFC. The observed decrease in forest cover loss ordeforestation rates over our study period was mainly due to lower clearingrates in the evergreen broadleaf forests in the states of Mato Grosso,Pará, and Rondônia. GFC indicated anomalously high forest cover loss inthe years 2007 and 2010, which was not reported by PRODES. The burned area dataindicated that this was predominantly related to increased burned areaoccurring outside of the tropical forest area during these dry years, mainlyin Pará. This indicated that fire and forest loss dynamics in woodlandsor secondary forests may be equally important as deforestation in regulatingatmospheric CO₂ concentrations. In addition to the decrease in forestcover loss rates, we also found that post-deforestation fire use declined;burned area within 5 years after forest cover loss decreased from 54 to39 % during our study period.

[学科分类] 地球化学与岩石