TROPICAL FOREST BIOMASS MAPPING FROM DUAL FREQUENCY SAR INTERFEROMETRY ( X AND P-BANDS )

Radar sensors operating with different wavelengths and polarizations have been widely used for large-scale forest mapping and monitoring. The interferometric phase obtained by microwave sensors contains additional information on the three-dimensional structure of the scattering targets in the image. An experiment was performed in the Brazilian Amazon (Tapajós National Forest and surroundings) to provide airborne SAR data at Xand Pbands over tropical rain forest. In a first step of the presented research the regular radar backscatter results are joined with an interferometric height model to establish a statistical relationship to forest biomass (primary and secondary vegetation). Subsequently, that model is applied for generation of a thematic land cover map. Backscattering of P-band waves mainly occurs on the ground surface, and can be used for interferometric generation of a Digital Elevation Model. The X-band is reflected by dossel, and thus relates to the forest canopy in a Digital Surface Model. The difference between both models has been shown to represent height of vegetation. Care was taken in establishing statistical models that relate dendrometric parameters from forest types to both P-band backscatter and interferometric height. A best biomass model [biomass = 44.965 + 13.887 × h int + 10.556 × σ°HH ] was established after comprehensive testing of a range of specific allometric equations to achieve statistically high precision in biomass prediction. A segmentation algorithm (hierarchical region growth) was applied to the remote sensing dataset to provide means for application of the biomass model to homogeneous landscape units with similar biophysical characteristics and site histories. A final mapping result displays forest biomass, and accounts for different successional stages and primary forest in intervals.