Biomass and structure estimation of primary and secondary tropical rain forests using AirSAR data

Summary form only given, substantially as follows. During the 1993 South American AirSAR Deployment fully polarimetric C-, L-, and P-band data have been acquired over a settlement area in Guaviare at the edge of the Colombian Amazon. Preliminary analysis showed obvious (qualitative) relations between backscatter level, tropical rain forest structure and age of secondary forests and other types of vegetation. A field survey carried out in selected plots resulted in an extensive ground truth data base comprising disturbed and undisturbed primary tropical rain forests (13 plots) and secondary forests of varying age (10 plots). For all plots a detailed inventory was made of, amongst others, lifeforms, dimensions of trunks, crowns and leaves, densities, strata and coverage per stratum. It is noted that different lifeforms, such as broad-leaved trees, palms, cecropia or platanillo, may have completely different backscatter characteristics and that their occurrence is strongly related to (secondary) forest age and human intervention. The inventory data was used to create input data for a radiative transfer model (UTACAN) developed at the University of Texas at Arlington. The complex structure of natural forests, and desired applicability for C-, L- and P-band, necessitated adaptation of the model. The present model can include many layers (three or more) and many types of scatterers per layer to describe different types of leaves and a range of branch and trunk dimensions and orientations. The first results of backscatter simulations are discussed.