Tree diversity assessment and above ground forests biomass estimation using SAR remote sensing: A case study of higher altitude vegetation of North-East Himalayas, India

摘要

Forest biomass is one of the significant components for assessing the productivity and sustainability of the forest's ecosystem. In the present study, the mapping and estimation of above ground biomass (AGB) was performed using field observations employing allometric equations and C band Sentinel 1A and L band Advanced Land Observation System (ALOS) Phased Array L-band Synthetic Aperture Radar (PALSAR) remote sensing satellite images for the parts of north eastern Himalayan forests, Arunachal Pradesh. Total 57 transects of 500 m x 10 m size was laid in West Kameng and Tawang districts (altitude range: 1047-4161 m) of Arunachal Pradesh, in which a total of 12203 individuals of 67 tree species (Diameter at Breast Height (DBH) range: 3.18-235.45 cm) was recorded. The study exhibited higher tree density (428 individuals' ha(-1)) and basal cover (7658.63 m(2)ha(-1)) in the studied forests. The highest above ground biomass was contributed by Castanopsis indica (103.82 t ha(-1)) followed by Pinus roxburghii (46.24 t ha(-1)) and Quercus semicarpifolia (23.14 t ha(-1)). Further, AGB was estimated using the Horizontal-Horizontal (HH), Horizontal-Vertical (HV) polarizations acquired by the ALOS PALSAR 50m mosaic (2008) dataset and Vertical-Vertical (VV), Vertical-Horizontal (VH) polarizations acquired by the Sentinel 1A dataset. The relationship between field based AGB and radar backscatter for selected sample plots was established using pair wise correlation. While comparing the two satellite-based SAR images, it is observed that high correlation between radar backscatter and field based AGB was observed in ALOS PALSAR as compared to Sentinel 1A SAR. This is due to higher sensitive to backscatter values and higher penetration level of L band ALOS PALSAR as compared to C band Sentinel 1A SAR. The correlation study indicates high correlation of HV polarizations in ALOS PALSAR (HV polarization R-2= 0.63; HH polarization R-2= 0.58) as compared to Sentinel 1A (VV polarization R-2=