Abstract: Nitrogen addition can change plant diversity and soil nutrient content in alpine meadows,but the relationship between plant diversity and soil nutrients under nitrogen input is not clear. Using alpine meadows in Chenduo County,Qinghai Province,as research object,plant phenotypic traits and soil nutrient contents were determined under different levels of nitrogen addition (N0 (0 g N·m ^-2),N1 (15 g N·m^-2),N2 (30 g N·m^-2),N3 (45 g N·m^-2),N4 (60 g N·m^-2)),including cover,height,biomass,total nitrogen,nitrate nitrogen,ammonium nitrogen,organic carbon,total phosphorus,and other related indicators. The results showed that the plant community diversity index decreased significantly (P<0.05) when the amount of pure nitrogen was 60 g·m^-2. The soil nutrient content changed differently as the level of nitrogen addition increased. There was a correlation between plant community diversity and soil factors under nitrogen addition. Soil organic carbon and ammonium nitrogen affected plant diversity the most. In conclusion,short-term nitrogen addition influenced plant community diversity by affecting soil C,N,P and their stoichiometric ratios in alpine meadows.

Key words: Alpine meadows, Plant diversity, Soil nutrients, Eco-metric characteristics

摘要： 为研究氮素添加对植物多样性与土壤养分含量的影响，本研究以青海省称多县高寒草甸为对象，在添加不同水平氮素（N0（0 gN·m^-2）、N1（15 gN·m^-2）、N2（30 gN·m^-2）、N3（45 gN·m^-2）、N4（60 gN·m^-2））后测定植物表型性状（盖度、高度及生物量）和土壤养分（全氮、硝态氮、铵态氮、有机碳、全磷）含量等相关指标。结果表明：当添加量为60 gN·m^-2时，植物群落多样性指数显著下降（P<0.05）；随着氮素添加水平升高，土壤养分含量变化不同。其中氮素添加下植物群落多样性与土壤因子间存在相关性。土壤有机碳和铵态氮含量是影响植物多样性最大的土壤因子。综上所述，短期氮素添加通过影响高寒草甸土壤碳、氮、磷含量及其计量比，进而影响植物群落多样性。

关键词: 高寒草甸, 植物多样性, 土壤养分, 生态计量特征