ESTIMATION OF FOREST ABOVEGROUND BIOMASS FROM DERIVATIVES OF VEGETATION-STRUCTURE PROFILES

Several studies have found that the vertical Fourier transform of lidar, interferometric SAR, and stereo photogrammetric profiles at empirically-determined spatial frequencies enables high-performance forest aboveground biomass estimation. Linear combinations of real and imaginary parts of Fourier transforms of Tomographic (multi-baseline) SAR (TomoSAR) profiles, from UAVSAR airborne data, generate ~20%-precision estimates of AGB in the Saskatchewan area of Canada. We found that this 20% precision can be improved to ~15%, a factor of 30% improvement in RMSE if, instead of using Fourier transforms of the profile itself, we use Fourier transforms of the spatial, vertical derivative of the profile. The formulation of this “derivative” algorithm is the subject of this paper.