Development of ecosystem carbon stock with the progression of a natural mangrove forest in Yingluo Bay, China

Mangrove ecosystems play an important role in mitigating climate change with their capacity to sequester and store carbon. Mangrove can store larger amount of carbon in their soil than any other tropical forests in the same latitude. The coastline is a highly dynamic environment, mangroves can develop at the mudflat with stands of different ages paralleling the shoreline. Hence, this study aimed to assess the role of mangrove growth on ecosystem carbon stock. Four sites, including natural mangrove stands with different ages (15, 45 and 80-yr-old) and mudflat were selected. Vegetation biomass and the soil carbon content from 0 to 100 cm were analyzed. Ecosystem carbon stocks (including biomass carbon stocks and 0–100 cm soil organic carbon stocks) of 15-yr-old, 45-yr-old and 80-yr-old stands are 171.57 t ha−1, 274.53 t ha−1 and 380.72 t ha−1,respectively, and are 1.76, 2.82 and 3.91 times higher, than that of the bare mudflat ecosystem (111.23 t ha−1). Moreover, the vegetation carbon stocks in 15-yr-old, 45-yr-old and 80-yr-old forest stands account for 33.78%, 17.74%, and 12.33% of the ecosystem carbon density, respectively. The annual accumulation rates of the ecosystem carbon stocks are 3.61 t ha−1, 3.43 t ha−1 and 2.78 t ha−1 for 15-yr-old, 45-yr-old and 80-yr-old stands, respectively. The mangrove stand characteristics and its soil properties were changed with the mangrove ages. The contribution of vegetation biomass carbon stock to ecosystem carbon stock increased along the chronology, while the soil showed the opposite pattern. The annual accumulation rate of ecosystem carbon stocks decreased along the chronology.