Journal of Marine Sciences ›› 2023, Vol. 41 ›› Issue (1): 55-67.DOI: 10.3969-j.issn.1001-909X.2023.01.005

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Seasonal variation in coastal saltmarsh carbon stocks, south bank of Hangzhou Bay

CHEN Yining1,2(), ZHANG Ziyan1,3, CHEN Luzhen4, ZHANG Jialin4, LIU Bing1,5, XIA Xiaoming1,2, WANG Xinkai1,2, CAI Tinglu1,2,*()   

  1. 1. Second Institute of Oceanography, MNR, Hangzhou 310012, China
    2. Key Laboratory of Ocean Space Resource Management Technology, MNR, Hangzhou 310012, China
    3. College of Ocean, Zhejiang University, Zhoushan 316021, China
    4. Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen 361102, China
    5. College of Harbor, Coastal and Offshore Engineering, Hohai University, Nanjing 210098, China
  • Received:2022-11-28 Revised:2022-12-23 Online:2023-03-15 Published:2023-04-28

Abstract:

Carbon stock variation observation forms the basis for coastal saltmarsh blue carbon sink accounting. In order to accurately estimate the carbon sequestration rate of coastal saltmarshes over a short-term scale (seasonal to annual), this study carried out field observations and sample collections within a coastal saltmarsh on the south bank of Hangzhou Bay, covering different seasons of 2022. This study was primarily based on high-resolution surface monitoring by Surface Elevation Table (SET) systems. The results revealed a seasonal plant growth pattern between March and September for both the native species Scirpus mariqueter and the exotic species Spartina alterniflora. In terms of belowground biotic carbon stock changes, over the growing season, the carbon stock increase for Scirpus mariqueter reached 11 g C·m-2 whilst this value was 56 g C·m-2 for Spartina alterniflora. The SET data indicated a sedimentation rate of 13.02 cm·a-1 within the Spartina alterniflora saltmarsh, higher than that of the Scirpus mariqueter saltmarsh, 12.30 cm·a-1. Calculating the sedimentation rate data with sediment bulk density and organic carbon content, the sediment carbon accumulation rate of Scirpus mariqueter saltmarsh was estimated to be 460 g C·m-2·a-1, lower than 588 g C·m-2·a-1 of the Spartina alterniflora saltmarsh. Combining the biotic carbon stock increase and sediment carbon stock increase, the carbon sequestration rate for the Spartina alterniflora saltmarsh was found to be 644 g C·m-2·a-1, higher than the value of Scirpus mariqueter saltmarsh, 471 g C·m-2·a-1. Thus, the difference in carbon sequestration abilities of native and exotic species should be considered for future coastal blue carbon management.

Key words: coastal saltmarsh, vegetation, surface elevation, carbon accumulation, carbon sequestration rate

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