Mapping halophyte species over salt marsh and tidal flats using TerraSAR-X

Abstract

The accurate mapping and monitoring of salt marshes is important in understanding their responses to sea-level changes, as well as marsh accretion and anthropogenic modification. This study presents a method and application results of mapping different halophytes over tidal flats and salt marshes using TerraSAR-X. Halophytes in salt marshes are sensitive to sea-level changes, sedimentation, and anthropogenic modifications. The boundary of an herbaceous halophyte patch is, however, difficult to determine using remotely sensed data because of its sparseness. We examined the ecological status of the halophytes and their distribution changes using TerraSAR-X and optical data. We also determined the optimum season for halophyte mapping. An annual plant, Suaeda japonica (S. japonica), and a typical perennial salt marsh grass, Phragmites australis (P. australis), were selected for halophyte analysis. Suaeda is a globally popular genus thriving in salt marsh, and there are about 110 species in the Suaeda genus thriving in salty habitats. Suaeda is particularly sensitive to sea level fluctuation. The seasonal variation for P. australis was not significant (1.06 dB standard deviation). Seasonal variation for the annual plant was, however, more significant (1.47 dB standard deviation) than that for the perennial grass, with a pattern of lower backscattering in winter and a peak in the summer. The border between S. japonica and ng different halophytes over tidal flats and salt marshes using TerraSAR-X. Halophytes in salt marshes are sensitive to sea-level changes, sedimentation, and anthropogenic modifications. The boundary of an herbaceous halophyte patch is, however, difficult to determine using remotely sensed data because of its sparseness. We examined the ecological status of the halophytes and their distribution changes using TerraSAR-X and optical data. We also determined the optimum season for halophyte mapping. An annual plant, Suaeda japonica (S. japonica), and a typical perennial salt marsh grass, Phragmites australis (P. australis), were selected for halophyte analysis. Suaeda is a globally popular genus thriving in salt marsh, and there are about 110 species in the Suaeda genus thriving in salty habitats. Suaeda is particularly sensitive to sea level fluctuation. The seasonal variation for P. australis was not significant (1.06 dB standard deviation). Seasonal variation for the annual plant was, however, more significant (1.47 dB standard deviation) than that for the perennial grass, with a pattern of lower backscattering in winter and a peak in the summer. The border between S. japonica and