Variabilidade espacial do estoque de carbono nos manguezais da Baía da Ilha Grande (RJ)

Abstract

The present study had as general objective to analyze the spatial variability of the carbon stock of mangroves of the Ilha Grande Bay (RJ), in order to provide subsidies for the conservation of these environments. Specifically, the objective is to test the hypothesis that the total carbon stock and per compartment (above- and belowground biomass) is higher in fringe forests compared to transition forests. Twenty-one plots (replicates) were used for structural characterization, sampling of sediment cores and measurement of physical-chemical parameters (interstitial water salinity, pH and Eh) established in fringe and transition forests of Jabaquara (JAB) Saco Grande do Corumbê (SGC), Saco do Mamanguá (SMA) and Barra Grande River (RBG). The results indicate control of the relative dominance of species by physicochemical factors, especially salinity of interstitial water, with Avicennia schaueriana dominating in the areas of higher salinity and Laguncularia racemosa and Rhizophora mangle in areas of lower salinity. Regarding the carbon stock in the aboveground biomass, which presented similar behavior to the structural development, the fringe forests present a higher average when compared to the transition forests, except for the JAB forest, where means and variances are similar. Comparing the mean values of the carbon stock in the belowground biomass between the physiographic types, the pattern found was the opposite of what was expected: the transition forests had a higher stock on their belowground biomass than the fringe forests. As a result, total carbon stock in the biomass did not show a clear trend of variation between the physiographic types. When compared to the carbon stock values found in the literature, the averages found in this study are within or above the expected range for the latitudinal range, which can be an indicator of high conservation status for these systems.