【摘要】 太湖平原西北部卜弋桥Zk01孔上部8m地层孢粉资料显示该地区自全新世以来植被与气候主要经历了三个阶段:1)11000—9500cal.aB.P.,地带性植被为壳斗科为主的亚热带常绿落叶针阔混交林。森林成分以栎属(Quercus)、青冈属(Cyclobalanopsis)、栗属(Castanea)、栲属(Castanopsis)/石栎属(Lithocarpus)和松属(Pinus)为主,同时混生有少量的枫香属(Liquidambar)、冬青属(Ilex)、水青冈属(Fagus)、桦属(Betula)、榆属(Ulmus)等乔灌木。本阶段孢粉浓度较高,气候较温暖湿润,为早全新世升温期;2)9500—3900cal.aB.P.,植被演替为中亚热带性质的常绿阔叶林。此阶段特别是8000cal.aB.P.以来,植被以青冈属为主的常绿分子获得大发展为特点。当时森林繁茂,气候暖湿且较为稳定,对应于中全新世大暖期(适宜期);3)3900cal.aB.P.以来,森林植被表现为次生性质的亚热带针阔混交林。青冈属、栎属骤减,松属、禾本科(Poaceae)及水龙骨科(Polypodiaceae)含量明显增升。本阶段孢粉浓度减为最低,据研究区周边的孢粉资料推测此时期气候温凉湿润。本阶段晚期森林植被受到人类的干扰,与人类活动密切相关的农作物如禾本科(35—45μm)、十字花科和菊科等花粉类型含量持续增多,表明研究区自全新世晚期以来出现了明显的人类活动的迹象。Zk01钻孔点位处古河道,磁化率和粒度证据揭示了研究点沉积环境全新世早期为河流相,水动力较强,中期水动力条件显著增强,晚期减弱。最后,结合孢粉资料和沉积环境简述了植被变化与沉积环境之间的关联。更多还原

【Abstract】 An 8.0-m-long sediment core from Boyiqiao Town, NW Plain, Jiangsu Province, provides detailed pollen-based information about changes in vegetation and depositional environment during the Holocene. The chronology frame is reconstructed using five valid radiocarbon dates including four AMS ages. Based on pollen analyses, granularity and magnetic susceptibility, we recognized three stages of vegetation development in phase with depositional environment: 1) 11 000-9 500 cal.aB.P., subtropical evergreen and deciduous broadleaved forests developed as the zonal vegetation in the study area. The forests were dominated by fagaceous trees, e.g. Quercus, Cyclobalanopsis, Castanea, Castanopsis/Lithocarpus and Fagus. Pinus is the next common taxa in association with some deciduous hardwoods such as Liquidambar, Betula and Ulmus, etc. Poaceae-Artemisia and Typha-Cyperaceae communities covered the open areas and bottomlands or lake-riversides, respectively. This vegetation indicates a warm and moist climate in the earliest Holocene, suggesting the climate towards warming since the last glacial termination in the study area. Sediments of the core Zk01 was deposited in an ancient river and granularity data show that the paleohydrodynamics was strong during the period; 2) 9 500—3 900 cal.aB.P., the forest expanded and was characterized by dramatic rise of broadleaved evergreens represented by Cyclobalanopsis. This vegetation points to a warm and wet climate coinciding with the Holocene Megathermal in China. The hydrodynamics of the river became much stronger in this stage, indicating the considerable rainfall related to the strong East Asia summer monsoon; 3) since 3 900 cal.aB.P., Cyclobalanopsis and Quercus retreated notably and gave way to Pinus gradually, indicating the secondary conifer-broadleaved vegetation disturbed by anthropogenic activity. Human disturbance became more pronounced and intensified in the late period of this stage (Zone III-2) evidenced by the significant rise of Aster-type, Cardamine and Microlepia. Poaceous pollen (35—45 μm) occurred considerably in Zone III-2, suggesting possible rice domestication in the study area.更多还原