报告题目：Northern Atlantic Late Glacial climatic oscillations and Northwest European ecosystem reactions

报告人：Dr. Falko Turner

Research Fellowship for International Young Scientists, CAS

主持人：朱立平  研究员

地  点：中国科学院青藏高原研究所办公楼915会议室

时  间：2014年6月6日（星期五）15：00－16：30

简 介：

Dr. Falko Turner毕业于德国汉诺威莱布尼茨大学，熟练掌握生态（植被调查、水质分析、多元统计）、地质（钻孔、剖面描述、模型）、古环境（孢粉分析、植物大化石分析）和古湖泊（地球化学元素、藻类化石、湖面重建）等研究方法。利用易北河流域的古河道及其充填物，阐述了晚更新世/全新世的气候突变对欧洲低地的地貌过程与生态系统（包括人类活动）影响过程。通过将盘星藻鉴定到亚种水平，并利用多变量统计，首次发现盘星藻种的变化明显反映了晚冰期到早全新世的强烈的北大西洋涛动，盘星藻种的组合变化，能够反映与温度相关的一些要素。通过盘星藻群落的空间大小测度能够反映其群落的数量，并进一步指示气候变化。

Abstract:

Late Glacial temperature oscillations are known to have been strong and broadly synchronous triggers of environmental change around the Northern Atlantic, cold periods after initial warming probably caused by meltwater pulses weakening the Atlantic meridional overturnic circulation and magnifying mean winter sea ice extent.

The main part of the talk presents a multiproxy record of Late Glacial ecosystem development in a riverine environment in Northern Germany. The evolution of the fluvial regime is shown to have been only partially in phase with the main temperature shifts. Reconstructions suggest that river dynamics were largely affected by vegetation cover stabilizing surface soils and reducing sediment load in the river channels. Two phases of high fluvial activity and new channel incision indicate changes from dry towards wetter climatic conditions, as confirmed by evident water level rises in riverine lakes. Representing archives with clear expression of climatic changes in the pollen record, the lake sediments were further used to test the value of subfossil remains of Pediastrum, a frequent but hitherto underinvestigated green algae group, as palaeoecological indicators. Reconstructing the species composition of Pediastrum assemblages by differentiation of taxa to subspecies level, it is shown that species shifts reflected the strong Late Glacial climatic oscillations pronounced and significantly. In addition, Pediastrum assemblages indicate some kind of climatic amelioration to have started already shortly before the main summer temperature transition at the onset of the Late Glacial, assemblages may thus have been sensitive to a slightly different climatic factor.

Finally, the presentation reviews available information on Pediastrum as a bioindicator for lake level change. While a low to medium positive correlation between Pediastrum concentration and water depth in shallow lakes seems to exist, a record from a South American lake shows that species identification can enhance reliability of lake level reconstructions considerably. However, interpretations are generally limited by the scarceness of records and especially by the lack of knowledge on modern distribution and ecology of Pediastrum taxa. The planned research in Tibetan lakes may be a contribution to infer more precise information from Pediastrum records. A short outline of the project is given.

欢迎各位老师和同学参加！