MONITORING PACIFIC COAST SALT MARSHES USING REMOTE SENSING

摘要: The rapid decline in the extent and health of coastal salt marshes has created a need for nondestructive methods evaluating condition marsh ecosystems. This paper describes simultaneous uses field sampling remote sensing approaches to understand ecosystem functions species distributions discusses implications monitoring using sensing. Three sites along Petaluma River near entrance into San Pablo Bay, California, which represented range soil salinity, water content, nutrients, were studied. Standing biomass was directly assessed by indirectly estimated through canopy reflectance. dominated almost monotypic stands Salicornia virginica, Spartina foliosa, Scirpus robustus. For Salicornia, we found positive relationship between salinity up threshold 42 g/kg, after declined monotonically with increasing salinity. No or at salinities >20 g/kg. Although significantly different levels nitrate ammonium nitrogen interstitial soils these sites, no strong relationships nitrogen. Soil nitrogen, contrast, positively related biomass. redox increased elevation distance from shoreline, while moisture H2S decreased. Canopy estimable remotely sensed spectral vegetation indices 58–80% accuracy depending on species. Simple Vegetation Index (VI) Atmospherically Resistant (ARVI) measured handheld spectrometers best estimators green high cover Salicornia. Adjusted (SAVI) (SARVI) gave estimates Global Environment Monitoring (GEMI) estimate Scirpus. developed spectra. VI used spatial patterns across Landsat satellite Thematic Mapper (TM) data. TM image showed corresponding zones abundance. Narrow band reflectance features spectrometer can be predict plant content (R2 = 63%). Interpolated field-measured shown relate variation moisture. Airborne Advanced Visible Infrared Imaging Spectrometer data, similar site. Results indicate that both production accurately determined measures. Species-specific differences characteristics may distribution abundance airborne images.