Observations on the relationship between SIR-C radar backscatter and the biomass of regenerating tropical forests

SIR-C SAR data were related to the above ground biomass of regenerating tropical forests in Amazonia, Brazil. C- and L- band SAR data in the conventional polarization configurations showed no significant relationship with forest biomass, which were estimated in the field to range from 63.8-141.1 tha -1. However, the strength of the relationships was increased through the use of backscatter ratios and stratification of the forests by dominant species. These results support the view that backscatter ratios enhance the relationship between radar backscatter and biomass, perhaps beyond some quoted radar saturation levels, by reducing the effect of differences due to forest type. They also demonstrate that an ability to differentiate between forests of different species composition, and canopy geometry, increases the strength of the relationship between the SAR backscatter and biomass.