Abstract: In the present study, the desert steppe in Yanchi County of Ningxia is taken as the research object, in order to understand the response of plant species diversity and community stability to the addition of N and P in desert steppe. Since 2020,the experiment of N and P additions was carried out every year for three consecutive years. A random block design was adopted in the experiment, urea was used for N fertilizer, and calcium superphosphate was used for P fertilizer. The vegetation survey data from September 2022 were used in the present study. It was found that the species richness index and the Shannon-Wiener index were both significantly reduced by the additions of the high level of N combined with the medium and high levels of P, and the Simpson index was significantly reduced by the addition of the high level of N combined with the medium level of P. Godron stability analysis showed that the control group had the largest Euclidean distance and the weakest community stability. When P was added alone, the community stability gradually increased with the increase of the amount of P addition. Species diversity in the desert steppe was positively correlated with community stability. In conclusion, high levels of N and P additions can reduce species diversity by inhibiting plant growth in the desert steppe. Adding P alone, and the combined addition of low and medium levels of P together with high levels of N can effectively improve community stability.

Key words: Nutrient addition, Degraded desert steppe, Ecological restoration, Euclidean distance, Plant diversity

摘要： 为深入了解荒漠草原植物物种多样性和群落稳定性对N、P添加的响应,本研究以宁夏盐池县荒漠草原为研究对象,自2020年开始,每年开展N、P添加试验,连续进行3年。试验采用随机区组设计,N肥选用尿素,P肥选用过磷酸钙,本文使用2022年9月的植被调查数据。结果表明：（1）高水平N复合中、高水平P添加显著降低了物种丰富度指数和Shannon-Wiener指数,高水平N复合中水平P添加显著降低了Simpson指数；（2）Godron稳定性分析发现,对照组欧式距离最大,群落稳定性最低；在单独添加P时,群落稳定性随着P添加量的增加而逐渐增强；（3）荒漠草原物种多样性与群落稳定性表现为正相关关系。综上所述,高水平的N、P添加可以通过抑制荒漠草原植物生长,使得物种多样性降低,单独P添加以及中、低水平的P与高水平的N复合添加可有效提高群落的稳定性。

关键词: 养分添加, 退化荒漠草原, 生态修复, 欧式距离, 植物多样性