Estimation of Forest Biomass using Envisat - ASAR data

摘要

This paper presents experimental results obtained with ENVISAT-ASAR space borne data of VV, VH and HH polarizations over the parts of Karnataka in the Western Ghats, India. The aim is to quantify various levels of above ground forest Biomass, Volume and Basal area with the help of empirical relationship of the backscattering coefficients with the ground inventory. Extensive field data were collected to characterize forest vegetation parameters in the plots. Ground inventory data such as GBH, tree height were collected. The above ground tree biomass (ABG) is estimated from the collected ground data using the existing allometric equations at stand level in study area. Dual polarized ENVISAT C-band Advanced Synthetic Aperture Radar (SAR) data of IS2 beam mode i.e., incidence angle ranges from 18.8°-26.1° were analyzed. The DN values of the ENVISAT-ASAR data are converted to backscattering coefficients. The forest in the study area holds 129-203 Mg ha~(-1) (1Mg=10~3 kg) of Biomass. Scatter plots were drawn between backscattering coefficients and Volume, Basal Area and Biomass for VV, VH and HV polarizations. Results show that with increase in the biomass levels, backscattering coefficient also increases. The backscattering coefficient of HH has significant correlation with the biophysical parameters whereas VH and VV are not well correlated. This relationship can be utilized to estimate the forest biophysical parameters of the study area.