Nitrogen deposition magnifies the sensitivity of desert steppe plant communities to large changes in precipitation

1. Precipitation alteration and nitrogen (N) deposition caused by anthropogenic activities could profoundly affect the structure and functioning of plant communities in arid ecosystems. However, the plant community impacts conferred by large temporal changes in precipitation, especially with a concurrent increase in N deposition, remain unclear. 2. To address this uncertainty, from 2016–2017, an in situ field experiment was conducted to examine the effects of five precipitation levels, two N levels and their interaction on the plant community function and composition in a desert steppe in northern China. 3. Aboveground net primary production (ANPP) and plant community-weighted mean (CWM) height significantly increased with increasing precipitation, and both were well fitted with a positive linear model, but with a higher slope under N addition. The ANPP increase was primarily driven by the increase in Artemisia capillaris, a companion forb sensitive to precipitation variation. The pla...1. 人为活动引发的降水格局改变与氮（N）沉降，可深刻影响干旱生态系统中植物群落的结构与功能。然而，降水的长期大幅变化——尤其是伴随氮沉降增加时——对植物群落造成的影响仍不明确。 2. 为厘清这一研究空白，研究团队于2016—2017年在中国北方的荒漠草原开展原位野外实验，探究5个降水梯度、2个氮添加梯度及其交互作用对植物群落功能与组成的影响。 3. 地上净初级生产力（Aboveground net primary production, ANPP）与植物群落加权平均（community-weighted mean, CWM）高度均随降水增加显著升高，且二者均符合正线性拟合模型，在氮添加处理下斜率更高。ANPP的提升主要由对降水变化敏感的伴生草本茵陈蒿（Artemisia capillaris）的生物量增加所驱动。本次研究的后续内容未完整展示。