Decomposition of forest litter plays a major role in nitrogen (N) dynamics in soil. However, the effect of new litter on indigenous soil N and its contribution to soil N in natural forest remains unknown. An in situ soil column experiment was conducted and ¹⁵N labelled litter was added to decompose for 14 months to examine the effect of litter retention on soil N dynamics in a typical subtropical forest. Litter removal in the soil column was used as a control. The results showed that litter removal caused a continuous decrease in concentration of soil soluble organic N (SON) in the first 5 months (August in 2018‐January in 2019), and SON concentration went up in the eighth month. Litter retention accelerated the reduction of soil SON concentration in the first 2 months, and SON concentration maintained a high value after that period. Soil NH₄⁺‐N derived from litter was nitrified rapidly, and the newly formed NO₃⁻‐N was quickly immobilized or lost. Only 1.8% of soil SON came from litter N and 98.2% from indigenous soil N under the decomposition of labelled litter. Litter provided N to form new soil SON continuously, however, only a small part of SON was relatively stable. Soil SON and total N (TN) are formed after long‐term litter accumulation and decomposition, and litter retention plays an important role in soil N dynamics.

中文翻译：

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在典型的亚热带森林中，对来自新凋落物或本地土壤的可溶性有机氮（SON）的来源进行定量

森林凋落物的分解在土壤中的氮（N）动态中起主要作用。然而，新型凋落物对天然土壤氮的影响及其对天然林中土壤氮的贡献仍然未知。进行了原位土柱实验，并进行了^15次添加N标记的凋落物分解14个月，以检查凋落物保留对典型的亚热带森林土壤N动态的影响。去除土壤柱中的凋落物作为对照。结果表明，清除凋落物导致头5个月（2018年8月至2019年1月）土壤可溶性有机氮（SON）浓度连续下降，而SON浓度在第8个月上升。最初的两个月，凋落物的滞留加速了土壤SON浓度的降低，此后SON浓度保持较高的值。土壤NH ₄ ⁺ -N从垃圾衍生迅速硝化，以及新形成的NO ₃ ^-‐N被迅速固定或丢失。在标记的凋落物分解下，仅土壤SON的1.8％来自凋落物N，而98.2％来自本地土壤N。凋落物不断提供氮，以形成新的土壤SON，但是，只有一小部分SON相对稳定。长期的凋落物积累和分解后形成土壤SON和总氮（TN），而凋落物的保留在土壤氮素动态中起着重要的作用。