非洲东南部晚更新世植被重建及对比研究有助于理解区域气候变化过程和驱动机制。本研究依托国际大洋发现计划IODP361航次科学任务所获取的U1477B海洋钻孔,对其上部4~37 m的沉积岩芯的79个样品进行了孢粉分析,重建了30~5 ka B.P.的区域植被和气候变化历史。研究结果显示,钻孔岩芯整体以草本植物禾本科(Poaceae)和莎草科(Cyperaceae)花粉为主,平均约占75.5%;木本植物花粉较少,以罗汉松科(Podocarpaceae)、豆科(Fabaceae)、使君子科(Combretaceae)和红树科(Rhizophoraceae)等为主;孢粉组合记录了钻孔孢粉源区赞比西河流域的植被特征。在时间演化序列上,钻孔沉积物孢粉组合变化反映出明显的冰期-间冰期(全新世)的植被变化特征:末次冰期(30~17 ka B.P.)以禾本科、莎草科等草本花粉为主,平均约占82.2%,以草原/草甸植被占优势,推测在流域低海拔平原开阔草原广泛发育;罗汉松科为代表的山地森林在冰期也相对发育,指示了相对凉爽潮湿的气候环境;冰消期(17.0~10.5 ka B.P.)禾本科花粉保持稳定平均约占38.3%,而莎草科花粉含量在前期略有增加后呈持续下降的趋势,反映了低海拔流域逐渐干旱的气候条件,非洲山地森林植被罗汉松科花粉达到最高值,反映了高海拔山地森林植被出现扩张;全新世早-中期(10.5~5.0 ka B.P.)罗汉松科花粉占比减少,而干旱林地典型植被豆科、使君子科等花粉增加,指示全新世早-中期气候相对温暖干燥;而红树科花粉占比迅速增加,指示海平面迅速上升扩大了适宜红树林生长的沿海空间。末次冰期到全新世中期流域内植被组成变化指示末次冰期相对潮湿寒冷、冰消期降水减少、全新世早-中期温暖干燥的气候条件,降水变化与同纬度(18°S)日照强度变化有较好的一致性。因此,钻孔孢粉记录的植被演化及降水过程可能受控于当地夏季日照强度并且对北半球高纬度冷�
0 INTRODUCTION.The intensification of global warming is generating increasing risks to human society and sustainable development,which are of growing concern to the international scientific community and policymakers(Sun,2023).The ecosystems of the Asian drylands are fragile and highly sensitive to global changes;moreover,while these drylands are the most important areas of oasis agriculture on Earth,their water resources are being adversely impacted by ongoing climate change(Zhang et al.,2023).Hence,an improved understanding of the patterns of climate change in this region is important and attracting increasing research attention.
Paleoenvironmental reconstruction is fundamental to understand the modern environmental changes and to predict future environment, which is especially critical to understand the evolution of land and sea during geological periods. However, the basic geological research on China＇s muddy coastal zone is not enough to provide quantitative data to compare with global changes. Therefore, in 2011, China Geological Survey deployed the ＂Late Quaternary geo-environmental evolution and modern process of China＂ project, and focused on the muddy coastal zones of the Liaodong Bay, Bohai Bay, the Yellow River Delta, Yangtze River Delta and Pearl River Delta （Fig. 1）. Next we will briefly introduce our latest results in the Bohai Bay.
WANG FuSHANG ZhiwenLI JianfenCHEN YongshengWANG Hong
