Abstract: In order to clarify the influence of enclosure on the grassland plant community and soil factors of Leymus secalinus,the experiment was conducted to observe the above-ground biomass and plant communities characteristics of the enclosure five-year-old Leymus secalinus grassland in the growing season,and to analyze the soil physical and chemical properties in different soil layers. The results showed that:after enclosure,the above-ground biomass,community cover and community height increased significantly (P<0.05),the Shannon-Wiener index and Margalef species diversity index were higher than grazing plots. The soil bulk density of 0~5 cm soil layer was significantly decreased (P<0.05),and the pH of each soil layer was significantly decreased (P<0.05),the soil carbon-nitrogen ratios in the soil layer of 10~20 cm and 20~30 cm were significantly higher than grazing plots,the soil nitrogen-phosphorus ratio in the soil layer of 20~30 cm was significantly lower than grazing plots (P<0.05). The soil carbon-nitrogen ratio drives the changes of plant communities in the enclosed plots. Soil total nitrogen,pH,nitrogen-phosphorus ratio drive the changes of plant communities in the grazing plots.

Key words: Leymus secalinus grassland, Fencing, Plant diversity, Ecological stoichiometry

摘要： 为了明确围封对晋北赖草（Leymus secalinus）草地植物群落及土壤因子的影响，本试验对围封5年的赖草草地植物群落生长季地上生物量和植物群落特征进行连续观测，以及对不同土层土壤理化性质进行分析，结果表明：围封后，草地地上生物量、群落盖度和群落高度显著增加（P<0.05），Shannon-Wiener指数和Margalef物种多样性指数均高于放牧地；围封草地0~5 cm的土壤容重显著降低（P<0.05），各土层的土壤pH均显著降低（P<0.05），10~20 cm，20~30 cm的土层中土壤碳氮比显著高于放牧地，20~30 cm的土层中土壤氮磷比显著低于放牧地（P<0.05）。土壤碳氮比驱动围封样地植物群落的变化，土壤全氮、pH、氮磷比驱动放牧样地植物群落的变化。

关键词: 赖草草地, 围封, 植物多样性, 化学计量比