Effects of Spartina invasion on the soil organic carbon content in salt marsh and mangrove ecosystems in China

• Published in: The Journal of applied ecology 2022-07, Vol.59 (7), p.1937-1946
• Main Authors: Xu, Xiao, Wei, Shujuan, Chen, Hongyang, Li, Bo, Nie, Ming
• Format: Article
• Language: English
• Subjects: Aquatic plants; biological invasion; blue carbon; Bulk density; Carbon; Carbon content; carbon sink; Climate change; Climate change mitigation; coastal wetlands; Ecosystem integrity; Ecosystems; Introduced species; Invasions; Kandelia obovata; mangrove; Mangroves; Migratory birds; Organic carbon; Organic soils; salt marsh; Salt marshes; Sanctuaries; Soil density; soil organic carbon; Soils; Spartina alterniflora; Suaeda salsa; Wetlands
• ISSN: 0021-8901; 1365-2664
• DOI: 10.1111/1365-2664.14202

Coastal wetlands are large reservoirs of soil carbon (C) and have been invaded globally by the exotic species Spartina alterniflora. However, the effects of these invasions on soil C content remain unclear. We performed a meta‐analysis of 2479 soil organic C (SOC) content observations collected from 91 field studies conducted in coastal China, the world's largest introduced range for S. alterniflora. Spartina alterniflora invasions had no significant effect on the SOC content in vegetated native wetlands in coastal China. S. alterniflora increased the SOC content in the top 30 cm of salt marshes after invading only one of the nine marsh types, which was dominated by a dwarf succulent species, Suaeda salsa in the northern subtropics and decreased the SOC content in the top 60 cm of mangroves dominated by Kandelia obovata and mixed communities after invasion in the southern subtropics. S. alterniflora invasions did not significantly affect the SOC content in the other salt marsh or mangrove ecosystems. Moreover, the SOC content in S. alterniflora‐invaded ecosystems increased only on a decadal scale and then decreased, rather than increasing monotonically. Synthesis and applications. Our findings reveal that the SOC content of S. alterniflora‐invaded ecosystems is similar to or lower than that of most native ecosystems. As soil bulk density is often reduced by S. alterniflora invasions, the C storage capabilities of vegetated native ecosystems might be substantially reduced after S. alterniflora invasions. Moreover, the SOC content in these invaded ecosystems gradually decreased after long‐term S. alterniflora invasions (>20 years). Therefore, the displacement of native salt marsh or mangrove species by S. alterniflora may not be considered a natural climate solution to increase the C sink in coastal China. Future efforts are required to control S. alterniflora preferentially in coastal wetlands where S. alterniflora invasions do not increase the SOC content, and to conserve and restore native coastal wetlands, which are the core areas of the World Natural Heritage site serving as China's Migratory Bird Sanctuaries that have been severely threatened by S. alterniflora invasions, to increase ecological integrity and C sinks and to mitigate climate change. 摘要 作为土壤碳的大型储存库，滨海湿地在全球范围内受到了外来物种互花米草(Spartina alterniflora)的广泛入侵。然而，到目前为止，互花米草入侵对土壤碳含量的影响仍不清楚。 在互花米草全球最大的入侵地——中国滨海湿地，我们从91项研究中收集了2479个土壤有机碳(SOC)含量数据，通过整合分析方法，探究了互花米草入侵对土壤有机碳含量的影响。 研究结果表明，整体上互花米草入侵对中国滨海湿地(盐沼和红