Biomass estimation from polarimetric SAR interferometry over heterogeneous forest terrain

Polarimetric SAR interferometry (Pol-InSAR) permits an accurate forest height extraction by inverting the SAR data with the Random Volume over Ground-model (RVoG). These forest heights were subsequently converted to forest biomass through forest height-biomass relation (allometry). Both the height extraction (L-band) and the allometric biomass conversion proved a good performance over dense forest stands. In open forests and stands of variable canopy height (here referred to as heterogeneous stands), the behaviour of the height extracting algorithm is unknown, and height-biomass allometry cannot easily be applied. To facilitate a direct biomass comparison of the Pol-InSAR-height extraction with ground measurements, the effective height h_eff was introduced as a direct biomass equivalent. Examples from spruce dominated sites of variable stand densities showed a sensitivity of the height extraction to the stand density, though not in correlation with the h_eff. It might be promising to exploit additional information from the shape of the extracted heights-histogram for an accurate biomass estimation even over dense and heterogeneous forests