Relationship between SAR and biomass derived from LiDAR in Mountain areas

In this paper, the response of ALOS (the Advanced Land Observing Satellite) PALSAR (the Phased Array type L-band Synthetic Aperture Radar) data to the forest biomass was analyzed in the Qilian Mountain area within Gansu province, western China. Due to not enough field biomass, the Light Detection and Ranging (LiDAR) data were used to extract biomass in a 20 m × 20 m cell. Then, the relationship between PALSAR backscattering coefficient in HH and HV polarization and LiDAR-derived forest above-ground biomass was analyzed. The result showed that at each biomass level, the range of backscatter coefficient in HH and HV polarization was very big and there was no obvious relationship between SAR backscatter coefficient and biomass in pixel scale, while after averaging backscatter coefficients in different biomass level, the backscatter coefficient in HV polarization increased with the increase of forest biomass and following one logarithm equation. The reason may be that forest structure is complex at pixel scale, while the average value partly removes the forest structure difference.