Journal of East China Normal University(Natural Science) ›› 2022, Vol. 2022 ›› Issue (6): 169-177.doi: 10.3969/j.issn.1000-5641.2023.03.017

• Estuary and Coastal Research • Previous Articles    

Study on sediment stability between vegetation and bare flats in a muddy intertidal flat: A case study for Chongming Dongtan in the Yangtze River Estuary

Yingxin ZHANG1, Wenxiang ZHANG1,*(), Benwei SHI1,2, Yaping WANG1   

  1. 1. State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China
    2. Key Laboratory of Coastal Science and Integrated Management, First Institute of Oceanography, Ministry of Natural Resources, Qingdao, Shandong 266061, China
  • Received:2022-01-20 Accepted:2022-04-25 Online:2022-11-25 Published:2022-11-22
  • Contact: Wenxiang ZHANG E-mail:wxzhang@sklec.ecnu.edu.cn

Abstract:

With the present global warming scenario, the erosion of intertidal flats in estuarine zones often occurs due to rising sea levels and an increase in human activities. Intertidal flats have an important ecological function and economic value, including for carbon sequestration, preventing flooding, water purification, attenuating waves, and tourism development. Hence, it is of great theoretical and practical significance to study the stability of the wetland ecosystem for intertidal flats. Previous studies mainly focused on the stability of intertidal bare flats, while the stability of salt marsh ecosystems has attracted relatively less attention. The mechanisms of their respective influencing factors are, as of yet, poorly understood. In this study, we took a typical muddy intertidal zone of Chongming Dongtan in the Yangtze River Estuary as an example and made a comparative analysis on sediment stability for both the salt marsh zone and the adjacent bare flat using in-situ sampling and laboratory tests. The results indicate that: ① Sediment stability improves with an increase of clay content in the bare flat. ② Sediment stability in the salt marsh zone is significantly higher than that in the adjacent bare flat because of the “reinforcing” effect of the root system. ③ Underground biomass determines sediment stability for the same type of vegetation. The sediment becomes more stable with an increase of the underground biomass in vegetation. The sediment stability of different vegetation is determined by characteristics of the vegetation root system. The sediment stability of Spartina alterniflora vegetation zone with coarser roots was worse than that of Scirpus mariqueter with finer roots. Our results not only advance theoretical research on sediment stability in intertidal flats, but also provide scientific guidance for the construction of Green Sea Defence and other coastal green protection measures.

Key words: sediment stability, critical shear stress, muddy intertidal zone, salt marsh vegetation, sediment grain size

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