The loess-paleosol sections of Jiyuan, Dingbian ( 37°08'24. 8"N, 107°23'25. 8"E, 1739m a. S. 1. ) and Helinge'er, Inner Mongolia (40° 12'52. 3"N, 111°41'8. 9"E, 1144m a. S. 1. ) located in the desert-loess transition belt, northern Loess Plateau were selected to carry out the high-resolution pollen record of research. Based on the comparison of magnetic susceptibility curves,grain size curves and the δ18O of stalagmite from Sanbao/Hulu caves during the last 50ka,the depth-age mode was established.76 pollen samples were identified to rebuild vegetation succession and explore its response to climate changes since MIS 3. At least 300 pollen grains were counted for most samples. 30 families and 24 genera of pollen were identified. Five pollen assemblage zones were divided in terms of the variations of main pollen percentages, pollen concentration and surface pollen researches for Jiyuan profile, and four pollen assemblage zones for Helinge'er section.A detailed history of vegetation succession and its response to climate changes since MIS 3 was reconstructed by a high-resolution pollen record. For Jiyuan section, during MIS 3 early term, the pollen assemblage consisting mainly of Picea,Artemisia and Chenopodiaceae seems to represent a sparse woodland and steppe; To MIS 3 medium term, the assemblage mainly consisting of Artemisia, Amnthemis type, Leguminosae and Tamarix might reflect a sparse steppe appearing; To MIS 3 late term-LGM, the increase of Chenopodiaceae suggests a desert steppe developed; To last deglaciation period, Artemisia, Tamarix and Chenopodiaceae assemblage seems to represent a steppe; To Holocene optimum,Artemisia, Taraxacum type and Leguminosae assemblage might suggest a meadow steppe. For Helinge'er section, during MIS 3 medium term, the pollen assemblage consisting mainly of Picea, Betula, Corylus, Artemisia, Leguminosae and Rosaceae seems to represent a steppe dominated by Artemisia and block sparse woodland distributed at the area of good moisture conditions; To MIS 3 late term-LGM, Artemisia, Chenopodiaceae, Leguminosae and Tamarix assemblage might suggest a desert shrub steppe dominated by Artemisia; To last deglaciation period, Artemisia, Aster type and Leguminosae assemblage seems to represent a steppe dominated by Artemisia; To Holocene optimum,Artemisia,Taraxacum type and Tamarix assemblage seems to suggest a meadow steppe dominated by Artemisia and Taraxacum types.The study results have shown that the vegetation on the Desert/Loess transitional belt has undergone 4 main stages since MIS 3: The vegetation was sparse woodland and steppe type during the early-middle MIS 3 phase; the desert steppe type during the late MIS 3 and the LGM; the steppe during last deglaciation; the meadow steppe type during the Holocene optimum. The vegetation secessions and climate changes since the MIS 3 phase suggest that the high temperatures benefited the development of vegetation and increased the plant diversity since the MIS 3 on the desert/loess transitional belt in Northern China.%选择沙漠/黄土过渡带姬塬、和林格尔两个地点的黄土-古土壤剖面开展较高分辨率花粉记录研究,重建MIS 3以来植被演替及其对气候变化的响应.黄土高原北部MIS 3阶段以来植被经历了4个主要阶段:MIS 3阶段早-中期气候较温湿,植被为疏林草原类型；MIS 3晚期-末次盛冰期为荒漠草原植被类型；末次冰消期为干草原植被类型；全新世高温期为草甸草原植被类型.沙漠/黄土过渡区MIS 3阶段以来植被演替显示,增温阶段和高温期有助于草原植被发育和植被盖度的增加,同时,全新世高温期有利于植物多样性增加.
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