Influence of Slope Aspect on above Ground Biomass Estimation using ALOS-2 Data

Synthetic aperture radar data has been extensively used for above ground biomass estimation of forest. The potentials of SAR data for biomass retrieval is well understood and documented in flat surfaces, whereas limited work has been carried in hilly surfaces. This study aims to investigate the influence of slope aspect on above ground biomass estimation using ALOS-2 PALSAR-2 data over Nongkhyllem Forest Reserve and Wildlife Sanctuary, India. Approximately 3 dB difference in the backscattering coefficient has been observed between area facing towards the sensor and shadowed area having specific AGB. Further, early saturation of backscatter in shadowed areas than in the areas facing towards the sensor due to increase in propagation length of signal through vegetation. The HV backscatter has shown high sensitivity towards AGB with r and RMSE of 0.7 and 38.84 t/ha respectively in area faces towards the sensor, whereas poor sensitivity with 0.61 and 45.58 t/ha respectively in shadowed areas. The analysis showed that the model generated without considering the slope aspect may lead to overestimation in the areas facing towards the sensor and underestimation in shadowed areas.