DH99a sediment core recovered at the center of Daihai Lake in north-central China was analyzed at 4-cm intervals for pollen assemblage and concentration. The pollen record spanning the last ca 10000 yr revealed a detailed history of vegetation and climate changes over the Daihai Lake region during the Holocene. From ca 10250 to 7900 cal yr BP, arid herbs and shrubs dominated the lake basin in company with patches of mixed pine and broadleaved forests, indicating a mild and dry climatic condition. Over this period, the woody plants displayed an increasing trend, which may suggest a gradual increase in warmth and humidity. The period between ca 7900 and 4450 cal yr BP exhibits large-scale covers of mixed coniferous and broadleaved forests, marking a warm and humid climate. Changes in the composition of the forests indicate that both temperature and precipitation displayed obvious fluctuations during this period, i.e., cool and humid ca 7900-7250 cal yr BP, warm and slightly humid ca 7250-6050 cal yr BP, warm and humid between ca 6050 and 5100 cal yr BP, mild and slightly humid ca 5100-4800 cal yr BP, and mild and humid ca 4800-4450 cal yr BP. The period can be viewed as the Holocene optimum (characterized by a warm and moist climate) of north-central China, with the maximum (dominated both by warmest temperatures and by richest precipitations) occurring from ca 6050 to 5100 cal yr BP. During the period of ca 4450-2900 cal yr BP, the woody plants declined, and the climate generally became cooler and drier than the preceding period. This period is characterized by a cold, dry episode from ca 4450 to 3950 cal yr BP, a warm, slightly humid interval between ca 3950 and 3500 cal yr BP and a mild, slightly dry episode from ca 3500 to 2900 cal yr BP, and appears to be a transition from warm and humid to cold and dry climatic conditions. Since ca 2900 cal yr ago, the forests disappeared and the vegetation density decreased, reflecting a cool and dry climate. However, a relative recovery of the woody plants occurring between ca 1700 and 1350 cal yr BP may denote an increase both in temperature and in precipitation. Fluctuations in the climatic condition of the Daihai Lake region were not only related to changes in the seasonal distribution of solar insolation and in the axis and intensity of the ocean current in the western North Pacific but were also closely linked to variations in the position and strength of polar high-pressure systems and in the pattern and intensity of the Westerly winds.

利用燕山地区几个主要植物的花粉-气候响应面模型，定量恢复了燕山南部5000a B. P.来的气候变化。5000a B. P.以来，燕山南部的气候曾发生过两次明显的降温事件，一次发生在4500～3600a B. P.，7月份平均气温比今低2.0℃左右；一次发生在2750～1750a B. P.，7月份平均气温比今低3.7℃左右；2000a B. P.以来年均降水量一直呈下降趋势，年均降水量比2000a B. P.前减少50～100mm。孢粉分析表明，燕山南部人工栽培板栗的历史可以追索到1600a B. P.，种植水稻的历史可以追索到700a B. P.。

岱海盆地99A孔11.01m以上地层较高分辨率的孢粉分析揭示了该区以来的植被演替和气候变化。早全新世时期，岱海盆地受冬季风影响强烈，气候波动以冷湿、暖干为主，12 000～11 000 cal a BP为以白桦林为主的森林草原植被，气候寒凉湿润；11 000～7 900 cal a BP白桦林退缩，气候温干；中全新世时，主要受控于夏季风影响下，气候波动以冷干、暖湿为主，7 900～4 450 cal a BP是岱海盆地森林植被发育最好的时期，气候温暖湿润，4 450～2 900 cal a BP森林开始退缩，气候温干；2 900～0 cal a BP在气候变凉干和人类活动的影响下，森林植被几近消失。

根据岱海盆地99a孔11.01m以上地层孢粉资料，运用孙湘君等所做的花粉-气候响应面定量重建了岱海盆地全新世以来的7月平均气温和年均降水量，结果表明，温暖湿润期的7月平均气温比今高约2～3℃，年均降水量比今多100～180mm；寒冷干旱期的7月平均气温比今低2～3℃，年均降水量比今少约40～120mm。全新世时期岱海盆地的气候曾发生过数次冷干、冷湿的降温事件和升温事件，冷干降温事件发生在10270、9500、8600、4400～4200、2800～1650 a BP，冷湿降温事件发生在7600～7400、5800～5600 a BP，升温事件发生在3750～3500、1650～1350 a BP。除2800～1650 a BP的寒冷期外，这些事件多持续了约200～300年便迅速结束。

Mordern alluvial pollen varies with geomorphic setting and depositional facies in sediments of the Yellow, Hutuo, and Luan rivers and in Baiyangdian and Hengshuihu lakes. Most of the arboreal pollen is derived from the mountains, whereas most of the nonarboreal pollen is derived from the plain itself. Alluvium dominated by Pinus pollen and Selaginella spores was deposited during a flood. Hydrodynamic sorting of alluvial pollen exists in the sediments of floodplain, central bar, natural levees, and point bar. In reconstructing the ancient vegetation and past climate based on pollen in alluvium, it is important to consider sedimentary facies and geomorphologic setting.