Evolution of shoals and vegetation of Jiuduansha in the Changjiang River Estuary of China in the last 30 years
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Evolution of shoals and vegetation of Jiuduansha in the Changjiang River Estuary of China in the last 30 years Fengrun Wu1, 2, Chunfu Tong1, 2*, Mitch Torkelson3, Yan Wang4 1 State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China 2 Institute of Eco-Chongming, Shanghai 200062, China 3 Department of Biology, Creighton University, Omaha, NE 68178, USA 4 Shanghai Environmental Monitoring Center, Shanghai 200235, China
Received 24 October 2019; accepted 20 December 2019 © Chinese Society for Oceanography and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract
The evolution of the shoals and vegetation plays an important role in maintaining the stability of the river regime and the estuarine ecosystem. However, the interaction between the evolution of shoals and vegetation dynamic has rarely been reported. In this study, we determined the interaction between the shoal and vegetation evolution of Jiuduansha in the Changjiang River Estuary in the last 30 years. We did this through the collection and summarization of the existing data of the regional hydrological processes, wading engineering, and vegetation, and combined it with the analysis of nautical charts and remote sensing images. During the past 30 years, the expansion of the shoals within the 0 m isobath in Jiuduansha was obvious, with an increase of 176.5%, while the expansion of the shoals within the 5 m isobath was relatively slow. The regional hydrological characteristics in the Jiuduansha area changed dramatically, especially the sediment discharges. The area of vegetation in Jiuduansha increased from 9.1 km2 in 1990 to 65.68 km2 in 2015, while the variations in the different vegetation types were different. The best combination of environmental factors with a significant correlation on the shoals within the 0 m isobath is the area of Spartina alterniflora and Phragmites australis. The evolution of Jiuduansha shoals was significantly affected by the variations in hydrological characteristics. Meanwhile, on a long-term scale, the expansion of the shoals could promote the regional vegetation expansions due to the suitable elevation and environmental conditions it provides. The interaction between the shoal and vegetation evolution varied in the different vegetation types and different elevations. In the future, long-term monitoring and detailed data are needed to the systematical analysis of the interaction between the hydrological processes and the evolution of the shoal and vegetation. Key words: Jiuduansha shoals, Changjiang River Estuary, vegetation, evolution Citation: Wu Fengrun, Tong Chunfu, Torkelson Mitch, Wang Yan. 2020. Evolution of shoals and vegetation of Jiuduansha in the Changjiang River Estuary of China in the last 30 years. Acta Oceanologica Sinica, 39(8): 71–78, doi: 10.1007/s13131-020-1636-7
1 Introduction Shoals formed by the deposition of sediments are widely distributed in muddy and sandy estuaries (Xie and Pan, 2012; Nelson et al., 2013). They usually develop with hig
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