Applying a common allometric equation to convert forest height from Pol-InSAR data to forest biomass

Abstract

Forest biomass (wood volume) is the most integrative forest structural parameter. Since no remote sensing technique can measure wood volume or biomass directly, a direct biomass determination from air- or spaceborne images always has a regression character. A different approach is to estimate forest biomass indirectly from a forest parameter that can be extracted more accurately than biomass, of which forest height is the closest related one. This makes it possible to utilize remote sensing methods that extract forest heights for biomass assessments: stereoscopic aerial photography, Lidar and Pol-InSAR. In this paper, forest heights were extracted from polarimetric interferometric SAR data (Pol-InSAR) over the spruce dominated test site ‘Fichtelgebirge’. The extracted heights proved a good correlation with the upper canopy height (h100, top height), and could be converted into forest biomass by means of height-biomass allometry. On this basis, the potential of Pol-InSAR systems for forest biomass estimation is critically discussed, and directions towards a performance optimisation are pointed out.