Forest biomass estimation in New Zealand using full-polarisation SAR imagery

Synthetic aperture radar (SAR) has been proposed as a method for estimating above-ground biomass, and this paper describes a method to estimate biomass over flat or sloping terrain. A theoretical model is used to make a correction for the terrain slope, along with a second model to decompose the backscatter into canopy, trunk and understorey layers. The method is semi-analytical, since it uses field-based ground truth information to calibrate the model, yielding canopy and trunk contributions to the above-ground biomass, and a relative indication of biomass contribution due to surface scattering. Qualitative analysis shows that the results generally conform to the model, but that artifacts in the digital elevation model, and limitations of the three-layer model, cause some instability in the solution. Modifications to these steps are under investigation.