The ability to retrieve forest stem volume using CARABAS (coherent all
radio band sensing) SAR images (28-60 MHz) has been investigated. The
test site is a deciduous mixed forest on the island of Oland in south
ern Sweden. The images have been radiometrically calibrated using an a
rray of horizontal dipoles. The images exhibit a clear discrimination
between the forest and open fields. The results show that the dynamic
range of the backscattering coefficient among the forest stands is hig
her than what has been found with conventional SAR using microwave fre
quencies. The backscatter increases with increasing radar frequency. T
his work shows an advantage compared to higher frequencies for stem vo
lume estimation in dense forests.