Background and aims Leaf litter decomposition constitutes a valuable ecosystem service by recycling nutrients, transferring energy, and sequestrating carbon (C) in terrestrial ecosystems. However, variations in microclimate and decomposers among studies have impeded a mechanistic understanding of what controls litter decomposition. We conducted a “common plot” experiment leveling-off impacts of environmental and biotic factors to explore roles of the initial leaf litter traits in decomposition. Methods The experiment was carried out in an evergreen broadleaf forest in the Wuyi Mountains from May 2017 to August 2018. Leaf litter was collected from Populus deltoids in a nitrogen (N) addition experiment at Dongtai Forest Farm, Liriodendron chinense × tulipifera and Platanus acerifolia on campus Nanjing Forestry University, and Quercus variabilis and Pinus taeda at Xiashu Forest Farm. Results Our results showed that N addition significantly increased leaf litter decomposition of P . deltoids . This may result from N induced increases in litter quality, indicated by a high N content and a low C:N ratio of leaf litter. Across the five tree species (with no litter from P . deltoids under N addition treatment), we found litter decomposition of the coniferous tree ( P. taeda ) was much lower than that of the other four broadleaf trees due to its lower litter quality. Multiple regression analyses indicated that the initial C:N ratio and sodium (Na) content that was critical for decomposers dominated decomposition. Conclusions Our results confirmed the importance of the initial litter quality, such as C:N ratio, in regulating leaf litter decomposition. In addition, our results suggest the Na control of the decomposition of leaf litter in subtropical ecosystems through Na limiting the activity and abundance of decomposers in brown food webs.

中文翻译：

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凋落物初始性状在调节凋落物分解中的作用：亚热带常绿阔叶林中的“共同小区”试验

背景和目标 落叶分解通过在陆地生态系统中循环养分、转移能量和固碳 (C) 构成了一种有价值的生态系统服务。然而，研究中小气候和分解者的变化阻碍了对控制凋落物分解的机制的理解。我们进行了一个“共同地块”实验，以平衡环境和生物因素的影响，以探索初始落叶性状在分解中的作用。方法 2017 年 5 月至 2018 年 8 月，在武夷山常绿阔叶林中进行落叶。在东台林场、鹅掌楸、梧桐树上进行氮（N）添加试验，收集杨树落叶。校园南京林业大学，和下树林场的栓皮栎和火炬松。结果 我们的结果表明，N 添加显着增加了 P 的凋落物分解。三角肌。这可能是由于氮引起的凋落物质量增加，表现为高氮含量和低碳氮比。在五种树种中（在加氮处理下，三角松没有凋落物），我们发现针叶树（ P. taeda ）的凋落物分解率远低于其他四种阔叶树，因为其凋落物质量较低。多元回归分析表明，对分解者至关重要的初始 C:N 比和钠 (Na) 含量主导了分解。结论我们的结果证实了初始凋落物质量（例如 C:N 比）在调节凋落物分解中的重要性。此外，