ERS SAR backscatter: a potential real-time indicator of the proneness of modified rainforests to fire

The 1997–1998 fires impacted upon huge areas of forests in Indonesia. Remotely sensed data have played an important role in both monitoring and publicizing the unfolding environmental tragedy and in postburn assessments of fire damage. This paper examines the potential of an active satellite system (European Radar Satellite [ERS]-2 Synthetic Aperture Radar [SAR]) to monitor the proneness of a range of vegetation types in East Kalimantan to burn, using a fire-related, daily drought index (DDI) as a proxy. The results indicate significant correlations between the C-band SAR backscatter and DDI values for a range of modified vegetation types, including dipterocarp forest with low to moderate disturbance. A deterministic relationship between backscatter and the fire-related DDI may thus exist, which implies that backscatter data could be used to monitor real-time changes in the proneness of vegetation to fire. A drought correlation map provides a synoptic view in the study area of differences in proneness of vegetation to fire.