Radar images are presently being used in association with optical remote sensing data to characterize the different processes of land use in Brazilian Amazon region. Considering the current development in remote sensing techniques for estimating forest biomass, where L, X and C band images have their limitations, it was recently accomplished a scientific airborne mission with image polarimetric P-band imagery acquisition at lower Rio Tapajós region, Brazil. This study analyses the biomass variation of the primary forest and secondary succession and it's influence on the response of backscatter values in the P-band polarimetric images. The start of this study was the understanding of the behavior of the structural variables of the vegetation cover (measured during the field survey) and its'correlation with the backscatter data obtained from PHH -, PHV - and PVV - band data. A statistical regression model was used to verify the relationship between biomass (estimate by different allometric equations) and P-band polarimetric data. Based on the regression equation that best fits the data sets, a biomass map was elaborated. This was done through the segmentation of the backscatter image, using Caesar 3.0 rwseg algorithm (based on the successive edge detecting and region growing procedures), with the σ° of each resulting segment was converted into biomass values by the best fit function. The final goal of this P-band experiment is to improve the regional inventory and monitoring biomass dynamics, as well as landscape changes, due to human action in Amazon.