Abstract: Mangrove forests are among the most productive coastal “blue carbon” ecosystems, and thus assessing and enhancing their carbon sequestration service value is crucial for addressing global climate change. Despite the growing activities in global blue carbon trading, the valuation of mangroves remains highly uncertain and is often underestimated. Taking the Gaoqiao mangrove forest in Zhanjiang as a case, we employed seven distinct methods to calculate its carbon sequestration service value and developed an assessment framework based on carbon enhancement strategies. Results showed that Rhizophora stylosa, Avicennia marina, Aegiceras corniculatum, and Bruguiera gymnorrhiza exhibited unit area carbon sequestration service value ratios of 1.59∶1∶1.18∶1.32, with R. stylosa and B. gymnorrhiza demonstrating the highest carbon sequestration value capacity. The total estimated value of mangrove carbon sequestration services ranged from 4.70 million to 61.90 million CNY. Methods such as the market price approach yielded conservatively low estimates by failing to account for the multifunctional ecological benefits, leading to a significant underestimation of their comprehensive value. Among the methods, Marginal Abatement Cost (MAC) and Carbon Capture and Storage (CCS) are most suitable for assessing carbon storage value, while the Social Cost of Carbon (SCC) and carbon tax methods are more appropriate for assessing carbon fixation value. Based on the dynamic assessment framework developed here, it is estimated that implementing moderate to high intensity management strategies could enhance the carbon sequestration service value of mangroves in the study area by 20% to 30% relative to the current baseline. Furthermore, our results clarified the applicable contexts of different valuation methods and revealed the significant carbon sequestration value and potential of mangrove ecosystems, thereby providing strong support for their scientific quantification and the formulation of comprehensive ecological conservation strategies.

Key words: mangrove, blue carbon, ecosystem service value, carbon fixation value, carbon storage value.