Aboveground net primary production and stand dynamics of mangroves along a river on Iriomote Island, southwestern Japan

Abstract

In this study, we examined the standing aboveground biomass, biomass growth, litterfall and tree species population dynamics of mangrove forest along the Nakara River, Iriomote Island, southwestern Japan, to explain the spatial patterns of stand structure and aboveground net primary production in reference to the stand dynamics of mangrove tree species along the river. The entire aboveground biomass of the mangrove forest did not vary with topographic position at the stand level, while three mangrove species showed different distributional patterns along the river. Although Bruguiera gymnorrhiza was generally dominant, Rhizophora stylosa codominated in the downstream areas. Kandelia obovata occurred only at the river’s edge in the downstream area. The observed spatial patterns of aboveground productivity of each species depended mostly on their biomass. The distribution patterns of the mangrove tree species were based on parameters of their population dynamics, such as growth, recruitment and mortality. The effects of disturbance, especially the effects of typhoons, on the forest dynamics were prominent in this study period. The results of the study suggest that the spatial pattern of species distribution and productivity could be largely affected by the typhoon disturbances.