Lateral movements of materials and energy in coastal wetlands, due mainly to tidal activities, have been recognized as key processes in understanding the biogeochemical cycles of ecosystems. However, our understanding of the roles of lateral movement in shaping ecosystem functions remains limited. Here we quantified the effects of lateral sediment transport on total carbon (C, inorganic + organic) and nitrogen (N) pools in plants and soils in two dominant wetland types: invasive Spartina alterniflora (Spartina) marshes and native Phragmites australis (Phragmites) marshes in coastal Shanghai of the Yangtze Estuary. We found that the accreted sediments across the water‐marsh gradients caused by lateral movement resulted in contrasting C and N contents between the two communities. The sediment load and C and N pools in the plants and soils of the Spartina marshes were significantly higher than those in the adjacent Phragmites marshes. The shifts in species composition and community structure not only altered the C and N balance but also enhanced the ecosystem net primary productivity. Our findings highlight the importance of lateral transport in altering ecosystem structure after Spartina invasion. The ecosystem C and N pools were significantly higher in the invaded ecosystems than in the native community. Our study also reveals that the plant density and structures can alter tidal hydrodynamics and the lateral transportations of sediments, which in turn influence ecosystem C and N cycle. The C accumulation processes of the native and invaded marshes were further complicated by the contrasting productivities of the ecosystems.

中文翻译：

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入侵互花米草的沿海湿地中碳和氮的横向交换增强

主要由于潮汐活动而引起的沿海湿地物质和能量的横向运动已被认为是了解生态系统生物地球化学循环的关键过程。但是，我们对横向运动在塑造生态系统功能中的作用的理解仍然有限。在这里，我们量化了两种主要湿地类型中侧向泥沙运移对植物和土壤中总碳（C，无机+有机）和氮（N）库的影响：入侵性互花米草（Spartina）沼泽和天然芦苇（Phragmites australis））在长江口上海沿海的沼泽地。我们发现，由横向运动引起的水沼泽梯度上的积聚沉积物导致两个群落之间的碳和氮含量形成对比。Spartina沼泽地的植物和土壤中的泥沙负荷和C，N库明显高于相邻的芦苇沼泽地。物种组成和群落结构的变化不仅改变了碳氮平衡，而且提高了生态系统的净初级生产力。我们的研究结果突出显示后改变生态系统的结构横向运输的重要性互花米草入侵。在入侵的生态系统中，生态系统的C和N库明显高于本地社区。我们的研究还表明，植物的密度和结构可以改变潮汐水动力和沉积物的横向运移，进而影响生态系统的碳和氮循环。生态系统生产力的差异进一步加剧了原生沼泽和入侵沼泽的碳积累过程。