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Purpose <p>Research on the invasive cordgrass <i>Spartina alterniflora</i> has predominantly focused on its detrimental ecological impacts. However, its role as a dominant coastal primary producer also implies a potentially massive, overlooked input of root-derived carbon to adjacent ecosystems. Despite the known significance of tidal carbon transport, the influence of root-exuded sugars, a highly labile and microbial-reactive fraction, on carbon cycling in recipient mudflats remains unknown. Given that <i>S. alterniflora</i> extensively invades these mudflat-saltmarsh ecotones, we aimed to determine whether the tidal transport of its root-exuded sugars could enhance microbial-mediated carbon sequestration, thereby revealing a previously unrecognized dimension of its ecosystem impact.</p> Materials and methods <p>Non-targeted metabolomics were manipulated to firstly discern the dominant sugars within <i>S. alterniflora</i> root exudates, and batch microcosm experiments simulating semi-diurnal tidal cycles and periodic hypoxia were conducted to compared the effects of these disaccharides on soil carbon dynamics. A control group (CK) was established, along with the other two groups treated by dominant sugars-analogues within <i>S. alterniflora</i> root exudates, i.e., the soil treated by α-lactose and trehalose. The samples were periodically collected after 1, 10, 30, 60 and 100 d, separately, and were used to detect a range of indicators, including soil physicochemical parameters, CO<sub>2</sub> emissions, carbon stability parameters and bacterial community.</p> Results and discussion <p>The results show that α-lactose and trehalose were identified as the dominant sugar constituents within <i>S. alterniflora</i> root exudates. Both sugars significantly increased recalcitrant soil organic carbon (RSOC) content, where the effect of α-lactose was the strongest (RSOC content increasing from 3.27 ± 0.01&#xa0;g kg<sup>− 1</sup> to 4.17 ± 0.20&#xa0;g kg<sup>− 1</sup>). Highly bioavailable α-lactose stimulated intense microbial metabolism, supporting carbon conversion during periodic hypoxia. This environment also reduced the abundance of aerobic heterotrophic bacteria such as <i>Sulfitobacter</i> and <i>Amylibacter</i>, further inhibiting carbon degradation. In comparison, trehalose had a lesser effect on RSOC accumulation: it triggered weaker microbial responses due to its role as an osmoprotectant, and its introduction increased soil conductivity, suppressing HRBIN37, which carries the function of carbon accumulation.</p> Conclusions <p>Overall, this work reveals that <i>S. alterniflora</i> invasion, despite ecological disruptions, can enhance carbon sequestration in adjacent mudflats via tidal introduction of root-exuded sugars, particularly α-lactose.</p>

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A potentially overlooked benefit of Spartina alterniflora invasion: tidal transport of root-exuded active sugars enhancing soil carbon accumulation via microbial-mediated processes in adjacent mudflats

  • 期刊论文

  • 发表日期：

    2026年3月4日

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  • Chunyu Tang,
  • Liu Luo,
  • Junqiang Shi,
  • Xuezhu Liu,
  • Wendong Xian,
  • Jianxin Wang

摘要

Purpose

Research on the invasive cordgrass Spartina alterniflora has predominantly focused on its detrimental ecological impacts. However, its role as a dominant coastal primary producer also implies a potentially massive, overlooked input of root-derived carbon to adjacent ecosystems. Despite the known significance of tidal carbon transport, the influence of root-exuded sugars, a highly labile and microbial-reactive fraction, on carbon cycling in recipient mudflats remains unknown. Given that S. alterniflora extensively invades these mudflat-saltmarsh ecotones, we aimed to determine whether the tidal transport of its root-exuded sugars could enhance microbial-mediated carbon sequestration, thereby revealing a previously unrecognized dimension of its ecosystem impact.

Materials and methods

Non-targeted metabolomics were manipulated to firstly discern the dominant sugars within S. alterniflora root exudates, and batch microcosm experiments simulating semi-diurnal tidal cycles and periodic hypoxia were conducted to compared the effects of these disaccharides on soil carbon dynamics. A control group (CK) was established, along with the other two groups treated by dominant sugars-analogues within S. alterniflora root exudates, i.e., the soil treated by α-lactose and trehalose. The samples were periodically collected after 1, 10, 30, 60 and 100 d, separately, and were used to detect a range of indicators, including soil physicochemical parameters, CO2 emissions, carbon stability parameters and bacterial community.

Results and discussion

The results show that α-lactose and trehalose were identified as the dominant sugar constituents within S. alterniflora root exudates. Both sugars significantly increased recalcitrant soil organic carbon (RSOC) content, where the effect of α-lactose was the strongest (RSOC content increasing from 3.27 ± 0.01 g kg− 1 to 4.17 ± 0.20 g kg− 1). Highly bioavailable α-lactose stimulated intense microbial metabolism, supporting carbon conversion during periodic hypoxia. This environment also reduced the abundance of aerobic heterotrophic bacteria such as Sulfitobacter and Amylibacter, further inhibiting carbon degradation. In comparison, trehalose had a lesser effect on RSOC accumulation: it triggered weaker microbial responses due to its role as an osmoprotectant, and its introduction increased soil conductivity, suppressing HRBIN37, which carries the function of carbon accumulation.

Conclusions

Overall, this work reveals that S. alterniflora invasion, despite ecological disruptions, can enhance carbon sequestration in adjacent mudflats via tidal introduction of root-exuded sugars, particularly α-lactose.