关键词: 呼伦贝尔沙地, 孢粉分析, 中新世环境变化

Abstract: There are three layers of paleosols in the light-yellow fine sand layer of the Hulun Buir Sandy-land,The analytical results of spore-pollen and ¹⁴C dating reflect that the sandy land experienced four fixed periods and four mobile periods since the Holocene.The spore-pollen assemblages in the paleosol indicated that the wood pollens were lese herb pollens occupied a dominant place and the paleobotanical successive series were subdesert steppe→Artemisia stepper→Sparse forest steppe→Chenopodi aceae and weed steppe.all of these vegetation types belongs to the type of sandyland grassland.According to the successive laws of ancient vegetation we must protect the sandland grassland and avoid the expansion of shifting sand.