Overemphasis on blue carbon leads to biodiversity loss: A case study on subsidence coastal wetlands in southwest Taiwan

This paper presents a methodology that accounts for biodiversity in calculating the carbon storage of bio-carbon sinks. The feasibility of this approach is demonstrated in the coastal wetlands of Tainan City. The wetland profiles adopted for this calculation method include information on local mangroves, such as Avicennia marina, Lumnitzera racemose, Kandelia obovat, and Excoecaria formosan. In the study area, wetlands, mangroves, windbreak forests, and biodiversity habitats collectively cover an area of 7,789, 202, 240, and 1447 ha and have a carbon storage of 581,820, 53,222, 92,794, and 67,159 tons, respectively. This approach demonstrates that while maintaining the biodiversity of the original intertidal zone, mudflat or salt marsh ecosystem, better biodiversity and carbon sequestration can be achieved through mangrove planting and mosaic habitat management during the implementation of carbon sequestration projects, highlighting the key role of biodiversity in carbon sequestration projects. In particular, the findings indicate that dredging and sand removal in Tainan’s Zengwen Reservoir has substantially prevented coastal erosion and restored the ecology of the Zengwen Estuary Delt. Finally, A. marina mangroves should not be planted on salt pans with land subsidence, such as closed hydrological systems.