Belowground net primary productivity stability in response to a nitrogen addition gradient in an alpine meadow

1.Temporal stability of ecosystem productivity is important for providing reliable ecosystem services under global changes. Great efforts have been made to explore the response of aboveground net primary productivity (ANPP) stability to nitrogen (N) enrichment, yet how it affects belowground net primary productivity (BNPP) stability remains elusive, which hinders a comprehensive understanding of ecosystem stability from the view of a whole system.
2. Here, using a field manipulative experiment with six N addition rates (0, 2, 4, 8, 16, 32 g N m-2 year-1), we explored the response patterns and drivers of BNPP stability in the topsoil (0-20 cm) and subsoil (20-40 cm) in the alpine meadow.
3. The results showed that BNPP stability at both soil depths showed a unimodal response to increasing N addition rates. Specifically, for both the topsoil and subsoil, low-level N addition significantly promoted BNPP stability, while high doses of N addition had no significant impact on BNPP stability, ...

1. 生态系统生产力的时间稳定性对于全球变化背景下提供可靠的生态系统服务至关重要。学界已围绕地上净初级生产力（aboveground net primary productivity, ANPP）稳定性对氮（N）富集的响应开展了大量研究，但氮富集如何影响地下净初级生产力（belowground net primary productivity, BNPP）稳定性仍不明晰，这阻碍了从全系统视角全面理解生态系统稳定性。
2. 本研究依托一项设置6个氮添加梯度（0、2、4、8、16、32 g N m⁻²·year⁻¹）的野外控制实验，探究了高寒草甸表层土壤（0-20 cm）与下层土壤（20-40 cm）中BNPP稳定性的响应模式及其驱动因子。
3. 研究结果显示，两种土壤深度下的BNPP稳定性均随氮添加速率升高呈现单峰响应特征。具体而言，无论表层还是下层土壤，低浓度氮添加均显著提升了BNPP稳定性，而高剂量氮添加对BNPP稳定性无显著影响，……