Comparison of tree height estimations from C and L-band InSAR data

Average height of forest stand is an important parameter related to forest ecological function and carbon cycling. Estimation of stand height using remote sensing data becomes possible due to the new technologies. Interferometry synthetic aperture radar (InSAR) technology uses the phase information of radar returns to get three-dimensional information of the earth surface. The existence of trees in a radar pixel modifies the phase information, so InSAR data has been studied for its potential of tree height estimation. In this study, the C and L-band InSAR data acquired during STR-C/X SAR Mission (1994) were used to estimate average tree height of forest stands in the Daxinganling forest region in Northeast China. The DGPS is used to locate each forest sample plot and the tree heights were measured in 1999. Tree heights in 1994 were deduced from the 1999 field measurements and the tree growth table. The results from C and L bands were compared. Following conclusions were drawn from the study: (i) Stand height information can be acquired from the digital surface model (DSM) generated from InSAR data, (ii) If the forest stand is very uniform in terms of tree height and density, the C-band InSAR data gives better result than L band. Otherwise, the results from L-band InSAR data are more stable, (iii) Multi-temporal InSAR technology may be used to monitor stand height increment.