MULTISCALE-MULTISENSOR APPROACH IN STUDYING WETLANDS OF THE PARANA RIVER DELTA REGION IN ARGENTINA

摘要

The Parana River Delta Region is a huge mosaic of wetlands which covers 17,000 km{sup}2 at the final portion of the Del Plata Basin in Argentina. This paper focuses on a brief review about how different sensors and a multi-scale approach bring insight on structural and functional features of wetlands, from regional to a specific ecosystem level in a top-down/botton-up approach. At broad scale, ENVISAT Wide Swath Mode (WSM) imagery along with optical SACC-MMRS and the last two decades of Normalized Vegetation Index (NDVI) time series of NOAA-AVHRR satellite systems were used to analyze landscape heterogeneity and wetland functioning in the whole region. The influence of "El Nino" flooding events was evaluated in different wetland landscape units. At fine scale, on the Lower Delta, detailed maps were produced using six Landsat Thematic Mapper images obtaining 28 wetland cover classes with an accuracy assessment of approximately 83%. In this region, special attention has also been given to the study of freshwater tidal marshes dominated by Scirpus giganteus. This marsh covers more than 40% of the Lower Delta surface, in the upper portion of the Del Plata Estuary. Net aboveground primary production (NAPP) field measurements were calibrated with NDVI derived from Landsat ETM+ surface reflectance values resulting in the first map of NAPP for the delta marshes. We also addressed the subject of ENVISAT ASAR imagery detecting aboveground biomass variations and water below the canopy.