Burn-scar patterns and their effect on regional burnt-area mapping in insular South-East Asia

This study aimed to deepen understanding on the limits imposed by burn-scar patterns and size distribution on regional burnt-area mapping with medium to coarse resolution (250-1000 m) satellite imagery in insular South-East Asia. Burnt-area maps based on 16 high-resolution SPOT 4 HRVIR and 5 HRG images were analysed in combination with land-cover and soil maps. Although the number of small burn scars (< 25 ha) was high throughout the region, the proportion of total burnt-area found in small scars varied remarkably (from 3 to 97%) between study sites. Unlike land cover, soil type was found to be a good indicator for usability of medium to coarse-resolution burnt-area mapping owing to the high occurrence of large burn scars on peatland and other wetland areas. A medium-resolution burnt-area mapping simulation (where 500 x 500-m grid cells containing >= 50% burnt area were considered detectable) resulted in 86% detected burnt area in wetlands (peat and alluvial soils) as opposed to only 33% in non-wetland areas. We thereby conclude that burn scar patterns and size distribution permit reliable regional burnt-area mapping with medium to coarse-resolution satellite imagery in the wetlands of insular South-East Asia, whereas alternative methods may need to be used in non-wetland areas.