Multifrequency and multipolarization radar backscattering from mangrove forests

The authors examine the dependence between multifrequency/multipolarization synthetic aperture radar (SAR) data and mangrove forest parameters. AIRSAR data at P-, L-, and C-band were acquired over French Guiana in June 1993. Structural parameters, namely, tree height, tree diameter at breast height (DBH), tree density, basal area, and total above-ground biomass were estimated in 12 stands representative of different mangrove forest stages. At the study site, total biomass ranges from about 5 to 437 tons of dry matter per ha (t DM ha^-1). Strong relationships were found between most forest parameters and radar data, with P-HV showing the greatest sensitivity to total biomass. Estimation of the forest parameters was performed through multiple stepwise regression techniques. While σ⁰ at P-HV saturated at about 160 t DM ha^-1, the use of several frequencies and polarizations allowed total biomass to be accurately estimated up to about 240 t DM ha^-1. Furthermore, the use of polarization ratios at different frequencies has provided useful information about the penetration capability of the radar wave as well as the dominant mechanisms occurring between the radar wave and the mangrove canopy