Estimate of net primary production of aquatic vegetation of the amazon floodplain using SAR satellite data

2 Instituto Nacional de Pesquisas Espaciais (INPE), Brazil Abstract-Field measurements were combined with synthetic aperture radar images to evaluate the use of RADARSAT and JERS-1 for estimating biomass changes and mapping of aquatic vegetation, and subsequently estimating of net primary productivity of aquatic vegetation in the lower Amazon. The combination of C and L bands provides the best correlation (r =0.82) and an intermediate saturation point (620 gm -2 ) for estimating above water biomass of aquatic vegetation. A combination of RADARSAT and JERS-1 images from each water period was classified using a region growing algorithm, and yielded an accuracy higher than 95% for the seasonal vegetated areas of the floodplain. The combination of the seasonal mapped area of aquatic vegetation with the statistical SAR-algorithm for estimating above water biomass and the percentage of below water biomass yielded a total annual NPP of 1.9x10 12 g C yr -1 (±28%) for aquatic vegetation.