OBJECT BASED DETECTION OF MULTISCALE CHANGES IN BRAZILIAN SAVANNAH USING SAR IMAGERY Luis Carvalho 1 , Geoffrey Hay 2 , Mike Wulder 3 , Fionn Murtagh 4 1 passarinho@dcf.ufla.br, Department of Forest Sciences – Federal University of Lavras, Brazil. 2 gjhay@ucalgary.ca, Department of Geography – University of Calgary, Canada. 3 mike.wulder@nrcan-rncan.gc.ca, Canadian Forest Service – Natural Resources Canada, Canada. 4 fionn@cs.rhul.ac.uk, Department of Computer Science – University of London, England. 1. INTRODUCTION Savannah-like and woody vegetation in the Brazilian’s Biome called Cerrado have been considered some of the most endangered ecosystems in the world, despite the stronger emphasis given to the “charismatic” Amazon forest. Threaten is relatively more eminent due to the existence of fertile soils and suitable terrain relief within the Cerrado, which makes it attractive for agricultural activities [1]. Less than 3% of the Cerrado Biome is currently protected under National parks or nature conservation areas [2]. Finally and most alarming are the estimates that more than 80% of the Biome has already been completely cleared out or irreversibly degraded due to anthropogenic activities [3]. In spite of this well-known critical situation, illegal vegetation removal is still taking place indiscriminately and some figures suggest that, unless effective monitoring and law enforcement efforts are urgently implemented, the Brazilian savannah might disappear in less than 25 years [2]. Changes taking place within the Cerrado Biome present a multiscale nature. They range from a few hectares, deforested for charcoal production, to thousands of hectares affected by single fire events every year. Hence, an effective monitoring system should be able to deal with this variability related to the size of changed areas. This fact has important implication for the design of appropriate analysis chains and for the selection of suitable input datasets. A few efforts in Brazil have tackled operational monitoring of savannah areas with remote sensing. Carvalho and Scolforo [4] have been using Landsat data to detect savannah removal in southeastern Brazil since 2003 on a biyearly basis. Modis data has been used in the work of Sano and Ferreira [5] for monitoring the savannah of central Brazil. Cloud cover seriously limits both mentioned monitoring systems in terms of updating frequency, and a search for alternative data sets to overcome this limitation has been considered. Another important aspect refers to automation. The Cerrado Biome covers approximately 200 million hectares (23% of the Brazilian