中文摘要：

为进一步了解养分添加和水分添加对干旱区草地植物多样性的影响，2009-2011年5月15日，对准噶尔盆地荒漠草地进行养分和水分添加，2009-2012年5月25日进行植被调查，研究群落结构与植物多样性对养分N、P、K与水分（雨、雪）添加的响应，得出以下结果：（1）添加肥、水后，荒漠草地植物群落结构发生了变化，物种数由肥、水添加前的17种减少到添加后的11种，减少了35．3％，禾草类植物数目增加，十字花科植物数量下降；（2）通过裂区试验方差分析，2009年和2010年，养分主效应对物种丰富度、Simpson指数、Shannon．Wiener指数、Pielou均匀度指数的影响不显著，水分主效应和肥水交互作用对以上4个植物多样性指数的影响也不显著；（3）2012年，养分主效应对物种丰富度影响显著p〈0．05），养分添加降低了荒漠草地物种丰富度，而水分作用、肥水交互作用对物种丰富度的影响均不显著；肥水交互作用对植物Simpson指数、Shannon．Wiener指数的影响显著仞〈0．05），而养分添加、水分添加对其影响亦不显著；（4）荒漠草地植物的Simpson指数、Shannon．Wiener指数、Pielou均匀度指数在年际间呈上升趋势。

英文摘要：

Aims Better understanding the response of community structure and species diversity to nutrient and water en- richment is critical for desert grassland in arid areas. Nitrogen, phosphorus and potassium are the three elements necessary for plant production, and water promotes plant absorption of nutrients. Our objective was to analyze the effects of nutrient and water addition on community structure and species diversity in typical desert grassland in northwestern China. Methods Field experiments were conducted in Gubantunggut Desert grassland from 2009 to 2012. Nutrient and water additions were done on May 15, 2009-2011, and vegetation investigation was conducted on May 25, 2009-2012. The responses of community structure and species diversity of plants to nutrient, rainfall and snow additions were studied. Important findings After the nutrient and water additions, the number of species decreased by 35.3%, the num- ber of species in Poaceae family increased and species in Cruciferae family decreased. In 2009 and 2010, none of the three treatments （nutrient addition, water addition and the coupling effect of nutrient and water） significantly influenced species richness, Simpson index, Shannon-Wiener index or Pielou evenness index. In 2012, nutrient addition had a significant effect on species richness （p 〈 0.05）, while treatments of water addition and the cou- pling effect of nutrient and water did not. The coupling effect of nutrient and water had significant influence on the Simpson and Shannon-Wiener indexes, while treatments of nutrient addition and water addition did not. The Simpson, Shannon-Wiener, Pielou evenness indexes increased from 2009 to 2012.