中文摘要：

以青海湖区4种不同植被被覆下温性草原为对象，研究在自然及放牧因素影响下土壤异质性分布格局。结果表明：速效养分（速效氮、速效磷、速效钾）具有明显的分层特征，表层土壤含量最高，随土层加深含量逐渐降低。紫花针茅退化样地各层土壤速效养分含量普遍低于其他3个样地,恢复时间较长的样地（早熟禾样地）和有外来物质输入的样地（赖草样地）含量较高。全量养分表现不同，全氮含量表现出分层现象，退化和恢复时间短样地（紫花针茅退化样地、垂穗披碱草样地）表层（0～10 cm）和第二层（10-20 cm）全氮含量高，下层含量迅速降低；早熟禾样地和赖草样地各层全氮含量都较高；全磷含量随土层降低没有出现显著差异（P〉0.05），紫花针茅退化样地0～40 cm土层全磷含量都显著低于其他样地（P〈0.05），其全钾和有机质含量也普遍低于其他样地；有机质与全量养分、速效养分均呈现极显著相关（P〈0.01）。随土层加深土壤容重增高，退化使土壤pH值升高。退化温性草原在恢复6 a后土壤基本得到恢复，人类扰动和自然因素都影响到土壤养分状况。

英文摘要：

Taking the temperate steppe under four vegetation types around the Qinghai Lake of Northwest China as test objects, this paper studied the distribution patterns of soil nutrient heterogeneity under natural condition and grazing disturbance. There existed obvious layering characteristics in the soil available N, P, and K, being the highest in surface layer （0-10 cm） and decreased with soil depth. In degraded Stipa purpurea steppe, the available nutrient contents in different soil layers were lower than those in Poe steppe, Elymus nutans steppe, and Leymus secalinus steppe. The Poe steppe which was restored for a longer time and experienced exotic substance input had higher contents of soil available nutrients. The soil total N content in degraded S. purpurea steppe and E. nutans steppe was higher in 0-20 cm layer, but decreased sharply below 20 cm depth. In contrast, both Poe steppe and L. secalinus steppe showed a higher soil total N content at each depth. The soil total P content had no significant correlation with soil depth （P〉0.05）, but was significantly lower at the depths 0-10 cm, 10-20 cm, 20-30 cm, and 30-40 cm in degraded S. purpurea steppe than in other three steppes （P〈0.05）. The soil total K and organic matter contents in degraded S. purpurea steppe were also lower than those in other three steppes. Soil organic matter content had significant correlations with soil total and available N, P, and K （P〈0.01）. Soil bulk density increased with soil depth. Degradation resulted in the increase of soil pH value. After 6 years recovery of degraded temperate steppes, the soil could be basically recovered. It was suggested that both grazing disturbance and natural factors could affect the soil nutrient status in temperate steppe.