REMOTELY SENSED L-BAND SAR DATA FOR TROPICAL FOREST BIOMASS ESTIMATION

Several attempts have been made to obtain forest stand parameters such as stand volume, stand density, basal area, biomass and carbon (C) stocks from synthetic aperture radar (SAR) data. However the relationship between these parameters and radar backscatter has been a challenging issue since the last several years. In this study, L-band ALOS PALSAR satellite image with a spatial resolution of 12.0 m was utilised to identify the relationship between radar backscatter and aboveground biomass of tropical forest stands. Forest Research Institute Malaysia (FRIM) which has about 420 ha of forest area was selected as the study area. Field survey was conducted in which 30 plots (50 × 50 m, 0.25 ha each) were established and all trees with diameters at breast height (dbh) of 5 cm and above were inventoried. The calculated plotbased biomass was correlated to the pixels of SAR backscatter corresponding to the plot size on the ground. The correlation function was used to determine stand biomass of the whole study area. Results showed that dense forest was sensitive to the backscatter on horizontal–vertical polarised (HV) image compared with horizontal–horizontal polarised (HH) image. It was also found that the L-band SAR backscatter had good capability to estimate aboveground biomass in mature stands of tropical forest.