OBSERVATIONS ON THE SENSITIVITY OF ERS-1 SAR IMAGE INTENSITY TO CHANGES IN ABOVEGROUND BIOMASS IN YOUNG LOBLOLLY-PINE FORESTS

A study was conducted to evaluate the sensitivity of the microwave ret urn recorded by the ERS-1 C-band synthetic aperture radar (SAR) to cha nges in above-ground woody biomass in young loblolly pine forests (dry weight biomass < 6 kg m-2). Radar backscattering coefficients were de rived from ERS-1 SAR imagery collected over 15 test stands near Durham , North Carolina, United States. Ground reference data were collected in order to characterize the aboveground biomass of the pine trees in the test stands. Significant linear correlations (at p = 0.001 or bett er) were found between the radar backscattering and the various compon ents of biomass (both wet and dry weight) of the pine canopy (e.g., bo le biomass, stem biomass, needle biomass, canopy biomass and total bio mass). The linear correlation coefficients ranged between 0.87 and 0.9 3. These results demonstrate the potential for using the C-band ERS-1 SAR to monitor biomass changes during the early successional stages in temperate coniferous forests, as well as throughout later successiona l stages in coniferous forests with lower overall growth rates, such a s those found in boreal regions.