PolInSAR Based Scattering Information retrieval for Forest Aboveground Biomass Estimation

Forests play a crucial role in storing carbon and are of paramount importance in maintaining global carbon cycle. Assessment of forest biomass at the regional and global level is vital for understanding and monitoring health of both tree species and entire cover. The changes in forest biomass are caused as a consequence of human activities, natural factors, and variations in climate. Thus, forest biomass quantification is necessary for gauging the changes in forest ecosystems. Hence, remote sensing techniques become indispensable for mapping forest biophysical parameters. Microwaves are capable of collecting data even in cloud cover and at night as the microwaves are of long wavelength. Microwaves help in retrieving scattering information of the target. The goal of this research was to map aboveground biomass over Barkot forest range in Dehradun, India. The current work focuses on the retrieval of PolInSAR based scattering information for the estimation of aboveground biomass. Radarsat-2 fully Polarimetric C-band data was used for the estimation of AGB in Barkot forest area. A semi-empirical model which is an extended water cloud model (EWCM) was utilized for AGB estimation. EWCM considers ground-stem interactions. Due to the overestimation of volume scattering polarization orientation angle shift was implemented on the PolInSAR pair. Field data was utilized for the accuracy assessment. The results show that coefficient of determination (R^2) value of 0.47, root mean square error (RMSE) of 56.18 (t ha-1) and accuracy of 72% was obtained between modelled biomass against field biomass. Hence, it can be inferred from the obtained results that PolInSAR technique, in combination with the semi-empirical modelling approach, can be implemented for estimating forest biomass.