Abstract Litter decomposition of perennial dominant species primarily regulates carbon and nutrient cycling in grassland, which is driven by litter quality, soil micro-environment, and the decomposer organisms. However, how does soil fauna contribute to litter decomposition remains poorly understood, especially for below-ground root at different decomposition stages in grassland ecosystem. Here in upland grassland, we simultaneously examined leaf and root litter decomposition rates of relatively higher-quality (Trifolium repens L.) and lower-quality (Lolium perenne L.) perennial dominant species over time in control and fauna-excluded treatments, using litterbags with different mesh sizes to limit the accessibility of soil mesofauna. We found that the presence of soil mesofauna significantly increased annual litter mass loss by 20.01%, and could amplify the effects of litter quality on decomposition. The larger contribution of mesofauna to root litter decomposition and higher inputs of root in grassland, suggests that a stronger role of soil mesofauna in accelerating grassland ecosystem processes than previously thought, and the leaves and roots need to be considered simultaneously when evaluating the role of soil fauna in litter decomposition. Furthermore, for lower-quality species, the disparities in the contribution of soil fauna to leaf and root litter only existed in the first 7 months, but disappeared in the subsequent 5 months. However, for higher-quality species, the stronger contribution of soil mesofauna on the root litter decomposition persisted at all decomposition stages. This suggests that the decomposition stage could affect the roles of mesofauna in leaf and root litter decomposition, and the interactive effects are largely dependent on litter species quality in grassland. Overall, our findings highlight the importance of incorporating the influence of these factors in global decomposition models, which may improve the accuracy of predicting biogeochemical process.

中文翻译：

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土壤中型动物群对草地优势植物叶根凋落物分解的贡献

摘要 多年生优势种凋落物分解主要调节草地碳和养分循环，其受凋落物质量、土壤微环境和分解生物驱动。然而，土壤动物群如何促进凋落物分解仍然知之甚少，特别是对于草地生态系统中不同分解阶段的地下根系。在高地草原，我们使用垃圾袋同时检测了相对较高质量（Trifolium repens L.）和较低质量（Lolium perenne L.）多年生优势物种在控制和动物群排除处理​​中随时间推移的叶和根凋落物分解率用不同的网格尺寸来限制土壤中型动物的可及性。我们发现土壤中型动物群的存在显着增加了年度凋落物质量损失 20.01%，并且可以放大垫料质量对分解的影响。中型动物群对根系凋落物分解的更大贡献和更高的草地根系投入，表明土壤中型动物群在加速草地生态系统过程中的作用比以前认为的更强，在评估土壤的作用时需要同时考虑叶片和根系垃圾分解中的动物群。此外，对于低质量物种，土壤动物对叶和根凋落物贡献的差异仅在前 7 个月存在，但在随后的 5 个月内消失。然而，对于更高质量的物种，土壤中型动物群对根系凋落物分解的更大贡献在所有分解阶段都持续存在。这表明分解阶段会影响中型动物群在叶和根凋落物分解中的作用，而交互作用在很大程度上取决于草地凋落物种类的质量。总的来说，我们的研究结果强调了将这些因素的影响纳入全球分解模型的重要性，这可能会提高预测生物地球化学过程的准确性。