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Spartina alterniflora has rapidly and extensively encroached on China's coastline over the past decades. Among the coastal areas invaded by S. alterniflora , at most 93% are mudflats. However, the effect of S. alterniflora invasion on soil organic carbon (SOC) stocks of coastal mudflats has not been systematically studied on a national scale. Here, we quantified the nationwide changes in SOC stocks in coastal mudflats associated with S. alterniflora invasion between 1990 and 2020. We found that S. alterniflora invasion significantly enhanced SOC stocks in coastal China. Nonetheless, the benefit of S. alterniflora invasion of coastal SOC stock may be weakened by continuing human intervention. We found that S. alterniflora invading mudflats added 2.3 Tg SOC stocks to China's coastal blue carbon, while 1.78 Tg SOC stocks were lost mainly due to human activities, resulted in a net SOC stock gain of 0.52 Tg C. These findings overturned the traditionally thought that S. alterniflora invasion would reduce ecosystem services by highlighting that the historical invasion of S. alterniflora has broadly and consistently enhanced blue carbon stock in coastal China. [ABSTRACT FROM AUTHOR]

Copyright of Functional Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Functional Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Two carbon (C) sources are of particular interest for soil organic carbon (SOC) storage under nitrogen (N) deposition: 1) glomalin-related soil protein (GRSP) and 2) microbial residual carbon (MRC) derived from microbial metabolites and residues. Both soil C sources are purported to have long residence times, but their contribution to SOC may be modified by changing soil N status. Methods: We assessed how N deposition influences GRSP and MRC as sources of SOC using soils from a long-term (11 years) N-addition site in a tropical forest in south China. We assessed differences in MRC and GRSP, microbial biomarkers, soil physico-chemical properties, and particle-size fractions between N-fertilized soils and controls. Results: Total GRSP, MRC, and SOC concentrations were higher under N-addition, but soil microbial biomass and community composition were largely unaffected, indicating that higher GRSP and MRC concentrations resulted from long-term accumulation and reduced microbial degradation. However, the relative contributions of GRSP or MRC to SOC were unchanged or lower than the controls due to a greater contribution of other C sources to SOC which were largely unstabilized by association with soil minerals. Conclusion: Tropical forests have great potential for SOC sequestration in response to N deposition which may help mitigate climate change. However, most of the additional SOC in N-fertilized soils was not associated with soil minerals, and thus prone to decomposition. [ABSTRACT FROM AUTHOR]

Casuarina equisetifolia plantations have been widely established along tropical and subtropical coasts, where they act as a windbreak to shelter coastal areas. These shelter plantations also fulfill another important ecosystem service by sequestering large amounts of carbon (C). However, shelter plantations are usually established on nutrient‐poor sand dunes, which may limit tree growth and therefore C sequestration rates. To assess whether fertilization increases the C sequestration of coastal shelter plantations, we conducted a fertilization experiment in a young C. equisetifolia plantation with four treatments: nitrogen addition (+N), phosphorus addition (+P), nitrogen and phosphorus addition (+NP), and controls (CK). We quantified nutrient availability and annual net ecosystem production (NEP) during the key early establishment phase. Fertilization with +N and +P significantly increased ammonium‐N and extractable P in the surface soils and the N and P concentrations of branches, respectively. Surprisingly, the mean growth rate of C. equisetifolia plantations (24.59 ± 0.66 Mg ha−1 yr−1) was not affected by fertilization. The mean NEP was 6.18 ± 0.49 Mg C ha−1 yr−1, and there was no difference among fertilization treatments. However, soil organic C significantly increased by 41% and 36% with +N and +P, respectively, but not +NP. C. equisetifolia plantations can sequester large amounts of C in biomass on poor soils without the need for additional nutrients, although fertilization may enhance soil C storage. Considering the potential large planting area, we suggest that coastal C. equisetifolia shelter plantations could be an important nature‐based solution for climate change mitigation in coastal regions. [ABSTRACT FROM AUTHOR]