中文摘要：

通过对位于黄土／沙漠过渡带定边地区苟池剖面的高分辨率的花粉分析，基于9个^14C年代数据重建了2400cal.aB.P.以来定边的植被与气候变化，结果表明2400-1740cal.aB.P.地带性植被为以栎为主的森林草原，气候较温暖湿润；1740-1610cal.aB.P.森林退化，草原发育，气候变干；1610-1240cal.aB.P.乔木成分增加，植被类型为疏林草原，气候较温和湿润；1240-1010cal.aB.P.森林退缩，草原发育，气候变干；1010-690cal.aB.P.草原进一步发育，气候干旱；690-500cal.aB.P.阔叶树成分增加，气候略温湿；500-190cal.aB.P.草原发育，气候干旱；190-0cal.aB.P.乔木成分增加，气候变湿。本区花粉记录的植被和气候变化可与区域的世纪初前后（秦汉）暖期、隋唐暖期、中世纪暖期和小冰期等事件对比。

英文摘要：

Based on the chronology of seven AMS 14C and two ＇4C dates, a detailed history of vegetation and climate change of the last 2400 years was reconstructed by a high-resolution pollen record from Gouchi, Dingbian （37°45′N, 107°31′E ; 1300m a. s. 1.） ,at the desert-loess transition in Northern China（Fig.1）. Dingbian is near the Maowusu desert in the north of Shaanxi Province,with the mean annual precipitation about 300mm. A section（200cm thick）was excavated by hand in the center of Gouchi Lake（a nearly dry salt lake,about 30km north of Dingbian） ,in and around which water system is poor except several seasonal rivers. 100 samples for pollen analysis were obtained at ca. 2cm intervals. The chronology is based on seven bulk AMS ^14C dates（ NSF AMS Facility at University of Arizona） and two ^14C dates（ Lanzhou University）. The calendar ages are calibrated using the CalibS. 0 calibration database. At least 300 pollen grains were counted for each sample. Pollen types were identified using reference material and published keys and photographs. 41 families and 57 genera of pollen were identified. Three pollen assemblage zones and seven sub-zones were divided in terms of the variations of main pollen percentages, pollen concentration and the result of CONISS analysis from the bottom to the top. A detailed history of vegetation and climate changes of the past 2400cal. a B. P. was reconstructed by a high- resolution pollen record. Between 2400cal.aB.P. and 1740cal. aB. P., the pollen assemblage mainly consisted of Quercus（0.45%-21.55%）, Pinus（0.34%-42.10%）, Chenopodiaceae （0-45.32% ）, Artemisia（4.16%-42.05%）and Ulmns （0.18% -4.6% ）seems to represent a forest steppe dominated by Oak landscape and a warmer and moister climate. During 1740 - 1610cal. aB. P., the increase of Artemisia （11.41%-40.22%） at the expense of Quercus （0.31%-7.05%） and Ulmns （0.34%-3.64%） probably might reflect that the steppe to expand, the forest to retreate and the climate to become drier.