Assessing Coastal Blue Carbon Sinks in Taiwan

Assessing Coastal Blue Carbon Sinks in Taiwan

Maintaining and enhancing blue carbon sinks have become an emerging priority to mitigate climate change. This study aims to assess the carbon sinks of coastal blue carbon ecosystems in Taiwan by collecting published journal papers, grey literature, and research reports to inventory the carbon sequestration and stock of the major coastal blue carbon ecosystems, including mangroves, seagrass beds, and salt marshes. The total area of salt marshes in Taiwan is 188 ha, of which the exotic species Spartina alterniflora in Kinmen accounts for 68˜ of the total. The largest area of coastal blue carbon systems in Taiwan is 5481 ha for seagrass beds, of which 5420 ha are distributed in Dongsha Island. Mangroves cover 681 ha. The carbon sequestration and stock of the representative species of salt marshes are 3.45~24.33 Mg C ha-1 yr-1 and 53.26~91.89 Mg C ha-1, respectively. The carbon sequestration and stock of the representative species of dominant intertidal seagrasses are 2.93~6.22 Mg C ha-1 yr-1 and 8.91~10.50 Mg C ha-1, respectively. The carbon sequestration and stock of subtidal seagrasses in Dongsha Island are 14.73 Mg C ha-1 yr-1 and 26.38 Mg C ha-1. The carbon sequestration and stock of mangrove species are 12.81~25.07 Mg C ha-1 yr-1and 134.50~292.23 Mg C ha-1. Based on the distribution area of each species, the total carbon sequestration capacity is 3,661 Mg C yr-1 for salt marshes, 80,619 Mg C yr-1 for seagrass beds, and 11,183 Mg C yr-1 for mangroves. The total carbon stock is 16,000 Mg C for salt marshes, 144,444 Mg C for seagrass beds, and 181,560 Mg C for mangroves. Combining the three blue carbon ecosystems, the total carbon sequestration capacity and stock is 95,463 Mg C yr-1 or 350,030 Mg CO2 yr-1 in Taiwan. Further actions are suggested to reduce the uncertainty in the carbon sinks of coastal blue carbon ecosystems in Taiwan.