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Linking Improvement of Soil Structure to Soil Carbon Storage Following Invasion by a C4 Plant Spartina alterniflora

He, Yanghui, Zhou, Xuhui, Cheng, Weisong, Zhou, Lingyan, Zhang, Guodong, Zhou, Guiyao, Liu, Ruiqiang, Shao, Junjiong, Zhu, Kai, Cheng, Weixin
Ecosystems 2019 v.22 no.4 pp. 859-872
C3 plants, C4 plants, Spartina alterniflora, aggregate stability, carbon sequestration, chronosequences, ecosystems, soil aggregates, soil aggregation, soil organic carbon, soil structure, stable isotopes, total nitrogen, wetlands
Coastal wetlands are increasingly recognized as important ecosystems for long-term carbon (C) storage. However, how soil aggregation mediates C accumulation and sequestration in these ecosystems remains unclear. Using the ¹³C isotope tracer from the invasion of a C₄ plant, Spartina alterniflora, into the native ecosystem originally covered by C₃ plants across Eastern Chinese coastal wetlands, we investigated a potential C stabilization process via soil structural protection. We quantified changes in soil aggregates, soil organic carbon (SOC), soil total nitrogen (STN), and natural ¹³C isotope abundance within aggregate fractions across a chronosequence of 0-, 4-, 8-, and 12-year S. alterniflora invasion. Our results showed that soil aggregate stability increased significantly along the chronosequence. Meanwhile, SOC and STN concentrations increased with invasion time in the whole soil and aggregate fractions, which were linked to increasing soil aggregate stability. The contribution of S. alterniflora-derived SOC increased from 18.96 to 40.24% in the 0–20 cm layer and from 4.66 to 32.04% in the 20–40 cm layer across the chronosequence from 4 to 12 years with the highest proportion observed in macro-aggregates. Our results indicate that invasion of S. alterniflora to coastal wetlands can sequester more C largely due to formation and stabilization of soil aggregates by soil structural protection.