Inference of forest biomass using P-band circular-polarized radar signals

Examines the possibility of using P-band frequency, circular-polarized radar signals for mapping and monitoring of forest biomass from space while at the same time minimizing the limiting effect of Faraday rotation. Several examples from various types of forests (temperate, boreal, and tropical) are presented and analyzed. Predicted biomass levels from the radar are compared to estimates from forest inventories at both linear and circular polarizations. The results show that the two kinds of estimates are in good agreement, except when the phase difference between HH and VV-polarization is large in which case RR or LL-polarized radar signals overpredict forest biomass. This situation is encountered in the presence of flooded forest, or very wet trees. Also, in areas where the P-band radar response from the forest saturates (biomass greater than 200 tons/ha), it is shown that polarimetric information allows further analysis of the scattered signals to obtain additional information on the vegetation characteristics. One analysis technique uses a Cloude decomposition of polarimetric scattering. In the case of tropical rain forests, this analysis technique helps separate different vegetation communities and habitats which can subsequently be related to different biomass levels