Effects of environmental change on radar backscatter in the Oregon Transect

During multisensor experiments in the Oregon Transect Ecosystem Research (OTTER) project, the JPL AIR-SAR collected data over six study sites in western Oregon. The SAR flights took place in June and August 1990 and March 1991. The sites ranged from the dense forests of the coastal region to the sparse inland Juniper forests, thus providing a wide range of above-ground biomass values (8 Tons/HA to 960 Tons/HA). The authors have previously reported the results of studying the polarimetric SAR data from June 1990. They concentrate on March 1991 data. These data were obtained under flooded conditions and colder temperatures. The variations of radar backscatter with biomass and other forest parameters are studied and compared to those from June 1990. Differences between radar backscatters of several dB have been observed. The authors´ observations substantiate their earlier findings that the radar measurements cannot be used to uniquely obtain the biomass, and that instead, inversion algorithms to find the fundamental scattering properties of forest components need to be used