Mapping invasive plant species in tropical rainforest using polarimetric Radarsat-2 and PALSAR data

Abstract

Radarsat-2 quad-pol data (C band) and both dual and quad-pol Phased Array L band Synthetic Aperture Radar (PALSAR) data are used to map invasive plant species and forest degradation in Betampona Natural Reserve, Madagascar. Polarimetric feature parameters including the amplitude of the HH-VV correlation coefficient, the polarization ratio HH/VV, the polarimetric phase differences and the linear depolarization ratio (HV/VV) are explored to indentify forest clusters and tree species. A full coherency matrix, a Freeman-Durden model based decomposition and a Cloud-Pottier eigenvalue-eigenvector decomposition are tested following a polarimetric speckle filtering procedure based on the Refined Lee filter. Then, Wishart unsupervised classification is performed, and the results are validated against ground truthing. Our results show that PALSAR polarimetric data holds great promise as a comprehensive survey method for the presence of invasive plant species in tropical rainforest.