Loss prediction of carbon stocks caused by Spartina alterniflora clearing in coastal wetlands of Yancheng, China

Spartina alterniflora as a C-4 plant has strong capacity for sequestering carbon, and due to its widespread establishment, potentially contributes to improving the carbon absorption capacity of coastal wetlands. However, its continuous expansion has seriously threatened the security and sustainable development of coastal wetland ecosystems. To cope with these issues, S. alterniflora clearing has been actively implemented in China in recent years. In this study, the CA-Markov model was applied to predict the spatial distribution of S. alterniflora in Yancheng coastal wetlands under natural growth conditions without human intervention in 2025 and 2030. The carbon stock loss was assessed by comparing the carbon stocks of S. alterniflora under natural and artificial clearing conditions. The inversion models of vegetation coverage and biomass were established to estimate the loss of carbon stocks caused by S. alterniflora clearing in Yancheng coastal wetlands. The area dominated by S. alterniflora in Yancheng coastal wetlands in 2025 and 2030 was predicted to be 176 km(2) and 205 km(2), and the average vegetation coverage was 0.73 and 0.75, respectively. Compared with 2022, the area increased by 47 km(2) in 2025 and 76 km(2) in 2030. From 1987 to 2022, carbon stocks of S. alterniflora in Yancheng coastal wetlands increased rapidly at first and then decreased slowly, from 0.26 x 10(5) t in 1987 to 1.41 x 10(5) t in 2022, with a maximum value of 1.65 x 10(5) t in 2002. By 2025 and 2030, the carbon stock loss caused by S. alterniflora clearing was predicted to be 1.93 x 10(5) t and 2.35 x 10(5) t, which was equivalent to a release of 7.08 x 10(5) t and 8.62 x 10(5) t of carbon dioxide. In 2025 and 2030, the loss of carbon stocks in section S4 (from Sheyang estuary to Doulong port) accounted for 33% and 29% of the total loss, and was the most seriously affected area. The study provided basic data for carbon compensation after S. alterniflora clearing and technical support for regional carbon management to aid future land management decisions.