Fig. 3
Peat extent boundary (red line) in the Bengkalis study area that was delineated based on visual interpretation of (a) background RGB composite (spectral bands 6-7-5) Landsat-1 image of 5 October 1972 and peat thickness measurements (black and white dots). For comparison, the peat extent boundary is also shown on (b) Sentinel-2 background RGB image of 4 August 2016 (spectral bands 11-8-5). Note that nearly all peat was still forested in 1972