Coupling Scirpus recruitment with Spartina control guarantees recolonization of native sedges in coastal wetlands

• Published in: Ecological engineering 2021-08, Vol.166, p.106246, Article 106246
• Main Authors: Li, Shi-Hua, Ge, Zhen-Ming, Tan, Li-Shan, Zhou, Ke, Hu, Zhong-Jian
• Format: Article
• Language: English
• Subjects: Accretion; Aquatic plants; Colonization; Corms; Coupling; Decision making; Deposition; Eradication; Estuaries; Estuarine dynamics; Germination; Hydrodynamics; Intertidal environment; Management strategy; Marshes; Monitoring; Morphology; Mud flats; Native species; Planting density; Positive feedback; Progradation; Propagules; Recolonization; Recruitment; Recruitment (fisheries); Reinvasion risk; Restoration; Restoration efficiency; Revegetation; Salt marsh; Scirpus; Seedlings; Spartina; Vegetation; Vegetation establishment; Wetlands
• ISSN: 0925-8574; 1872-6992
• DOI: 10.1016/j.ecoleng.2021.106246

Recruiting native coastal vegetation and preventing the reinvasion of exotic Spartina alterniflora is a major challenge in China, due to harsh tidal environment for vegetation establishment and rapid Spartina colonization. This paper first reviewed the revegetation course of native Scirpus mariqueter in a coastal wetland in the Yangtze Estuary, where the adjacent Spartina was effectively eliminated. From 2014 to 2019, the area of planted Scirpus increased by 26.7 times, and the plant density and biomass growth amounted to the levels of mature sedge community. The establishment of Scirpus promoted the sedimentary accretion with an annual sedimentary rate of 9.2 cm yr−1, which was significantly higher than that in the mudflat. Six years of monitoring revealed that the revegetation approach with belowground propagules (corms) was effective for Scirpus establishment under strong hydrodynamic disturbances in the tidal mudflat because the morphology and germination rate of corms benefited the anchoring function of seedlings. Both recruited Scirpus and the original community expanded constantly due to positive feedback between plant progradation and sedimentary accretion. Then, we implemented a model simulation under the scenario of Spartina retention. The prediction showed that the high-speed invasion of Spartina would colonize and replace the whole Scirpus community in the study area during the period of 2014–2019. Hence, our results highlighted the importance of coupling Scirpus recruitment with Spartina eradication in guaranteeing recolonization of native coastal sedges. As a long-lasting management strategy, unremitting field monitoring and assistant decision-making tools (such as the forecasting models) on Spartina reinvasion risk are highly suggested for preserving the restoration of native marshes. •Rhizocorms of native Scirpus are ideal revegetation material in tidal environment.•Positive feedback between plant and sediment favors both Scirpus and Spartina.•Spartina reinvasion is a high risk for restoration of native Scirpus.•Management strategies are suggested for Scirpus recruitment and Spartina control.