Abstract: In order to explore the stoichiometric characteristics of soil C∶N∶P and the physical and chemical properties of soil driving the variation in plant composition and distribution,a field study was conducted in a saline-alkaline grassland located in the agro-pastoral zone of north Shanxi Province. Vegetation and soil samples were collected from three saline-alkali degraded stages (light salinization,medium salinization and heavy salinization),and redundancy analysis (RDA) was used to evaluate relationship changes between plant communities and edaphic factors with the increase of salinization. The results revealed that grassland salinization significantly reduced vegetation height,coverage,density and productivity but increased Margalef index. Soil water content (SWC),bulk density (BD),pH and electrical conductivity (EC) significantly increased from the lightly saline-alkali grassland to the heavily saline-alkali grassland,whereas soil total phosphorus content and C/N decreased significantly. The N/P and total nitrogen content in topsoil (0~10 cm) firstly increased and then decreased with the salinization succession,peaking at the moderately saline-alkali degree. SWC,pH,C/P and C/N drove the changes of plant communities in the early salinization stage,and BD and EC drove the changes in the later stage.

Key words: Saline-alkali grassland, Carbon,nitrogen and phosphorus, Soil stoichiometry, Vegetation restoration

摘要： 为揭示晋北农牧交错带盐碱草地土壤化学计量特征及其与植物多样性间的关系，本试验以不同盐碱梯度的草地为研究对象，分析轻度、中度和重度盐碱草地土壤理化性质及其化学计量比对植物群落的影响。结果表明：随着盐渍化程度加剧，植被高度、盖度、密度和地上生物量均明显降低，而Margalef指数呈上升趋势；土壤含水量、容重、pH、电导率均显著升高，全磷含量和碳氮比不断下降，氮磷比和表土（0~10 cm）全氮含量先增加后减少，中度盐渍化程度时最大。土壤含水量、pH、氮磷比和碳氮比驱动盐碱化早期植物群落的变化，土壤容重、电导率推动中度和重度盐碱草地植物群落的分化。

关键词: 盐碱草地, 碳氮磷, 土壤生态化学计量学, 植被恢复