The nitrogen (N) cycle, a major biogeochemical cycle in forest ecosystems, notably affects ecosystem multifunctionality. However, the magnitude and role of organic N and the snow season remain uncertain in this cycle. We assessed the N flux and pool data of a temperate deciduous broad-leaved forest to clarify N cycle processes. The results showed that the most important component of the N pool was the soil N pool. The N demand of the site amounted to 139.4 kg N ha−1 year−1 and was divided into tree production (83.8%) and bamboo production (16.2%). We clarified that retranslocation (37.4%), mineralization at a soil depth of 0–5 cm (15.3%), litter leachate (4.6%), throughfall (2.3%), and canopy uptake (0.5%) provided 60.1% of the N demand. In terms of soil at 0–5 cm in depth, the net mineralization rate during the snow season contributed to 30% of the annual mineralization. We concluded that the study site was not N-saturated as a result of a positive N input–output flux budget. More than half of the total N was accounted for by dissolved organic N flowing through several pathways, indicating that organic N plays a vital role in the cycle. The mineralization rate in the soil layer during the snow season is an important link in the N cycle.

中文翻译：

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寒温带落叶阔叶林的氮循环

氮（N）循环是森林生态系统中主要的生物地球化学循环，显着影响生态系统的多功能性。然而，有机氮的大小和作用以及雪季在这个周期中仍然不确定。我们评估了温带落叶阔叶林的氮通量和池数据，以阐明氮循环过程。结果表明，氮库最重要的组成部分是土壤氮库。该场地的氮需求量为 139.4 kg N ha−1year−1，分为树木产量（83.8%）和竹子产量（16.2%）。我们澄清，再迁移（37.4％）、0-5厘米土壤深度的矿化（15.3％）、凋落物渗滤液（4.6％）、渗透（2.3％）和冠层吸收（0.5％）提供了60.1％的氮要求。就0~5 cm深度土壤而言，雪季净矿化率占全年矿化量的30%。我们得出的结论是，由于正的氮输入-输出通量预算，该研究地点并未达到氮饱和。总氮的一半以上是通过多个途径流动的溶解有机氮，这表明有机氮在循环中起着至关重要的作用。雪季土层矿化率是氮循环的重要环节。