pan lang="EN-US">A sediment core was collected from the northeast of the Huangdong Reservoir in Huizhou, Guang dong province. Environmental 137Cs and ^210Pb dating techniques pan>pan style="font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（pan>pan lang="EN-US">mainly with^137Cspan>pan style="font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）pan>pan lang="EN-US"> were applied to determine the chronology and modem sedimentation rates of the Huangdong Reservoir, by combining with the sediment lithology, grain size and the historical data on the construction of the reservoir. Meanwhile, a lab analysis was conducted on the pollen analysis and charcoal to explore the significances to the environment and reveal the past environmental changes, vegetation and ecological conditions of the reservoir. The grain size analysis re sult showed that the sedimentation rate was faster pan>pan style="font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（pan>pan lang="EN-US">approximately 1.5 crn/apan>pan style="font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）pan>pan lang="EN-US"> before the construction of the reser voir; and it decreased pan>pan style="font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（pan>pan lang="EN-US">approximately 1.0 cm/apan>pan style="font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）pan>pan lang="EN-US"> after the construction of the reservoirpan>pan style="font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（pan>pan lang="EN-US">since 1960span>pan style="font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）pan>pan lang="EN-US">. The re cords on pollen assemblages and charcoal revealed that the pollens of herbs pan>pan style="font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（pan>pan lang="EN-US">such as Gramineaepan>pan style="font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）pan>pan lang="EN-US">, spores of fern pan>pan style="font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（pan>pan lang="EN-US">such as Dicranopteris dichotomapan>pan style="font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）pan>pan lang="EN-US"> and Pinus were relative with the human activities. The concentration of pollen and AP/NAP ratios pan>pan style="font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（pan>pan lang="EN-US">arboreal pollen/non-arboreal pollenpan>pan style="font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）pan>pan lang="EN-US"> were the important indicators to reveal the changes of the forest coverage. Human activitiespan>pan style="font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">＇pan>pan lang="EN-US"> influence on vegetation was manifested in the decrease in pollens of tree, the drop in the total concentration of pollens, the increase in pollens of herbs. And it showed that the bare land or water and soil loss increased significantly if humans cut down and burned frequently. Sig nificant large areas of forest fire events could be according to peak value of charcoal concentration as well as the C/P value pan>pan style="font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（pan>pan lang="EN-US">ratio of charcoal and pollenpan>pan style="font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）pan>pan lang="EN-US">. This study revealed the vegetation ecological information of three different stages in the basin, i.e. the period before the construction of the reservoir, the period of Great Leap Forward and the Cultural Revolution, and the subsequent period of reform and opening up. Such information tmcovered the changes of human activities in modes and intensities indifferent historical periods. The results of pollen assemblages and charcoal index analysis were consistent with the main events of the great Steel-Mak- ing movement in 1958, the hundred-year drought in 1963, and the afforestation project in 1986 which were re corded in the historical documentsl.pan>
