The use of airborne CARABAS-II VHF (20-90 MHz) SAR data for retrieval of fo
rest parameters has been investigated, The investigation was performed at a
test site located in the southwest: of Sweden consisting mainly of Norway
spruce forests. Regression models predicting forest parameters from radar b
ackscattering amplitude were developed and evaluated. The results showed a
linear relationship between backscattering amplitude and forest stem volume
, stem diameter, and tree height. The analysis also showed that the radar s
ignal is strongly affected by ground slope conditions. The root mean square
errors from the regression analysis, restricted to forest stands on near-h
orizontal ground, were found to be 66 m(3) ha(-1), 3.2 cm, and 2.3 m for st
em volume, stem diameter, and tree height respectively. No saturation of th
e backscattered signal was observed up to the maximum stem volume of 625 m(
3) ha(-1), corresponding to a biomass of 375 tons ha(-1). The results imply
that VHF SAR data have significant potential for operational use in forest
ry.