Inversion of leaf area index for invasive plant using ENVISAT ASAR

In this paper, leaf area index LAI retrieval of invasive plant species from C-band synthetic aperture radar (SAR) data was demonstrated to be feasible via experiment. Taking an invasive plant of spartina alterniflora in Dongtan of Chongming island, Shanghai, China as example, a specific method that inversion LAI of invasive plant from the ENVISAT dual-polarization Advanced Synthetic Aperture Radar (ASAR) imagery would be presented in the paper. In the experimental test, the functional relationship model between the LAI values and backscattering ratio values was at first built and the model parameters were then objectively calculated by fitting, using simulated LAI values according to published research work and backscattering ratio values converted from the ENVISAT ASAR images. Moreover, it is confirmed in our study that it is being computablely functional relationship between the LAI and the image pixel for either HH polarization mode image or VV polarization mode of ENVISAT ASAR image. The experimental conclusions are finally revealed that: 1) The 2-polynomial fitting is better than the 1-polynomial for both HH polarization mode image and VV polarization mode in approximation degree; 2) The difference of using the 1-polynomial fitting and the 2-polynomial fitting as adopting the HH polarization mode image is larger than the one as adopting the VV polarization mode image; 3) Adopting the HH polarization mode image is more effective than adopting the VV polarization mode image in inversion LAI for invasive plant from ENVISAT ASAR image; and 4) the related coefficient between the LAI and backscattering ratio corresponding to ENVISAT ASAR image were acquired up to 0.7100 in the HH polarization mode and 0.6657 in the VV polarization mode.