中文摘要：

以乌拉特荒漠草原3种典型植被群落及其不同深度土层为研究对象, 比较不同群落及其土壤碳、氮含量差异。结果显示, 1）小针茅（Stipa klemenzii）群落的植被盖度显著高于芨芨草（Achnatherum splendens）和红砂（Reaumuria soongorica）群落（P〈0.05）, 但其地上生物量却显著低于其他两个群落;2）3种植被群落间的C含量差异不显著;N含量则表现为芨芨草〈小针茅〈红砂群落, 且差异均达到显著水平;C/N表现出红砂〈小针茅〈芨芨草群落, 差异均达显著水平;3）小针茅群落的土壤有机碳含量在0-30 cm层显著高于其余两群落, 红砂群落土壤表层（0-10 cm）全氮含量则显著高于另外两群落。不同植被类型各土层的C/N存在一定差异, 但变化没有随着土层深度的增加呈现出规律性。

英文摘要：

This study determined soil carbon, nitrogen contents and C/N of 3 typical vegetation communities in Urad desert steppe. The results showed that： 1） the vegetation coverage of Stipa klemenzii community was significant higher than Achnatherum splendens and Reaumuria soongorica communities （P〈0.05）, while its aboveground biomass was the lowest among 3 communities. 2） the carbon content of 3 vegetation communities was not significant different; but the nitrogen content and C/N of 3 vegetation communities showed significant different, which ranked as A.splendens〈S.klemenzii〈R.soongorica and R.soongorica〈S.klemenzii〈A.splendens respectively; 3） Soil organic carbon content of S.klemenzii community was significant higher than the other two communities, especially in 0-30 cm soil layer, and the total soil nitrogen content of R.soongorica community was the highest among 3 vegetation communities in 0-10 cm layer. There were some differences of soil C/N in different types of vegetation, but the change was not consistent with soil depth.