Soil organic carbon (SOC) in temperate forests is a crucial part of the global C cycle. The C and nitrogen (N) inputs may greatly increase in forest ecosystems affected by atmospheric CO₂ concentration, N deposition, and other climate change, which may further affect SOC dynamics in temperate forests. Nevertheless, how C and N inputs interact to influence the soil priming effect (PE) in the organic and mineral layers of temperate forests remains unclear. Here, we used easily available C and N sources, such as ¹³C-glucose with 2% SOC contents and ammonium nitrate (input C:N ratio = 10), to examine the effects and mechanisms of exogenous C and N inputs on soil CO₂ production and PE in both soil layers of a temperate forest. Our research revealed that exogenous C input caused a positive PE in both soil layers, with the mineral layer showing a larger PE per unit of SOC than the organic layer (OL). Although C input increased C loss from native SOC, soil net C accumulation still increased. The C and N inputs decreased the soil PE in both soil layers, suggesting that N input alleviates substrate N limitation and weakens microbial N mining in both soil layers. Meanwhile, the C and N inputs increased the exogenous C remaining in the organic layer, which was beneficial for soil C sequestration. Compared to the organic layer, the response of the mineral layer to C and N inputs was weaker. This study suggests that C and N interact to affect PE on SOC decomposition and this interaction should be considered in modeling and prediction of soil C cycling.

中文翻译：

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温带森林氮开采机制对有机层和矿物层的土壤引发效应


温带森林中的土壤有机碳 （SOC） 是全球 C 循环的重要组成部分。在受大气_CO2 浓度、氮沉积和其他气候变化影响的森林生态系统中，C 和氮 （N） 输入可能会大大增加，这可能会进一步影响温带森林的 SOC 动态。然而，C 和 N 输入如何相互作用影响温带森林有机层和矿物层中的土壤引发效应 （PE） 仍不清楚。在这里，我们使用了容易获得的 C 和 N 来源，例如 SOC 含量为 2% 的 ¹³C-葡萄糖和硝酸铵（输入 C：N 比 = 10），以研究外源 C 和 N 输入对温带森林两个土壤层土壤 CO₂ 产生和 PE 的影响和机制。我们的研究表明，外源 C 输入导致两个土壤层的 PE 均为正，矿物层每单位 SOC 的 PE 大于有机层 （OL）。尽管 C 输入增加了原生 SOC 的 C 损失，但土壤净 C 积累量仍然增加。C 和 N 输入降低了两个土层的土壤 PE，表明 N 输入减轻了基质氮的限制，削弱了两个土层的微生物氮开采。同时，C 和 N 输入增加了有机层中残留的外源 C，有利于土壤 C 的固存。与有机层相比，矿物层对 C 和 N 输入的响应较弱。这项研究表明，C 和 N 相互作用会影响 PE 对 SOC 分解的影响，在土壤 C 循环的建模和预测中应考虑这种相互作用。