Fig. 1. Location of the study area

Fig. 2. Flowchart of this study

Fig. 3. The reflectance spectra of mangrove， water body， tidal flat and terrestrial vegetation

Fig. 4. The images of five mangrove indices for Yingluo Bay and Pear Bay

Fig. 5. Histograms of five mangrove indices

Fig. 6. The threshold range of five mangrove indices

Fig. 7. Mangrove distribution results extracted based on five indices and empirical thresholds for Yingluo Bay and Pear Bay

Fig. 8. The distributions of mangrove forests in Pearl Bay， Guangxi

Fig. 9. The distributions of mangrove forests extracted by five improved indices with NDWI optimization for Yingluo Bay and Pear Bay

Fig. 10. Probability map of mangrove distribution using five indices for Yingluo Bay and Pear Bay

Fig. 11. The distributions of Guangxi coastal mangrove forests extracted by MVI after NDWI optimization