State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
University of Chinese Academy of Sciences, Beijing, China.
Ecol Lett. 2022 Aug;25(8):1869-1878. doi: 10.1111/ele.14065. Epub 2022 Jun 28.
Increased nitrogen (N) inputs are widely recognised to reduce soil respiration (Rs), but how N deposition affects the temporal dynamics of Rs remains unclear. Using a decade-long fertilisation experiment in a boreal larch forest (Larix gmelini) in northeast China, we found that the effects of N additions on Rs showed a temporal shift from a positive effect in the short-term (increased by 8% on average in the first year) to a negative effect over the longer term (decreased by 21% on average in the 11th year). The rates of decrease in Rs for the higher N levels were almost twice as high as those of the low N level. Our results suggest that the reduction in Rs in response to increased N input is accelerated by high-level N additions, and experimental high N applications are likely to overestimate the contribution of N deposition to soil carbon sequestration in a boreal forest.
氮（N）输入的增加被广泛认为会降低土壤呼吸（Rs），但 N 沉降如何影响 Rs 的时间动态仍不清楚。本研究利用中国东北落叶松（Larix gmelini）林长达十年的施肥实验，发现 N 添加对 Rs 的影响表现出时间上的转变，即短期（第一年平均增加 8%）呈正效应，而长期（第 11 年平均降低 21%）呈负效应。高 N 水平下 Rs 的下降速率几乎是低 N 水平的两倍。研究结果表明，高 N 添加加速了 Rs 对增加 N 输入的减少，而实验性高 N 应用可能高估了 N 沉降对北方森林土壤碳固存的贡献。
