Palynomorph- and chironomid-based analyses of Eemian, Weichselian, and Holocene ecosystem- and climate dynamics in the Baltic Sea region

该项目的主要目标是确定和量化波罗的海地区从伊米亚到全新世的生态系统和气候动态。这一目标将通过在IODP 347远征期间从波罗的海取回的五个地点产生千年至百年尺度的孢粉形态记录来实现。应对花粉和孢子进行分析，以评估陆地生态系统和气候变化。陆地领域的定量降水和温度数据将通过对花粉组合应用最近生活亲缘关系方法和现代相似技术来生成。对于海洋沉积物，应在与陆地孢粉形态相同的样品中分析甲藻包囊和其他海洋替代物，以定性评估海洋领域的同年温度和盐度变化。一个主要的工作假设是，基于植被的定量气候重建方法将在较长的温暖间隔期间提供准确的结果，特别是在中/晚伊米亚和中/晚全新世，但植物迁徙滞后将阻碍较短温暖间隔(例如，魏氏间期)和早期间冰期的重建。由于要分析的地点位于从波罗的海北部到南部的路线上，如果所有剖面都能采用一致的年龄模型，就应该有可能确定移徙影响。此外，摇蚊幼虫遗骸应用于湖泊沉积物的样本，以获得与植被无关的气候数据。对于海洋领域，除了甲藻包囊外，合作者分析的替代物将能够进行定性和可能也是定量的温度重建。波罗的海区域是此类分析的一个特别感兴趣的区域，因为它位于高纬度和中欧和南欧之间，也处于不同植被带(南部的寒温带森林和北部的封闭的北方森林)之间的过渡地带。在这些地点被钻探的盆地中，高沉积速率保证了高时间分辨率和良好的孢粉形态保存。在目前正在进行的IODP-Expedition-347岸上探险队之前和期间进行的试点研究表明，在不同地点的细级配沉积物中，孢粉形态保存得非常好，湖泊沉积物中含有水生昆虫幼虫的遗骸。这项研究的结果将有助于更详细地了解北欧的环境和气候动态，并有助于理解过去13万年来北半球的气候遥相关。

The main goal of this project is the identification and quantification of ecosystem and climate dynamics in the Baltic Sea region from the Eemian to the Holocene. This goal shall be achieved via the generation of millennial- to centennial-scale palynomorph records from five sites retrieved from the Baltic Sea during IODP Expedition 347. Pollen and spores shall be analysed to assess terrestrial ecosystem and climate change. Quantitative precipitation and temperature data for the terrestrial realm will be generated via the application of the nearest-living-relative method and the modern analogues technique to the pollen assemblages. For marine sediments, dinoflagellate cysts and additional marine proxies shall be analyzed in the same samples as the terrestrial palynomorphs, to qualitatively assess coeval temperature and salinity changes in the marine realm. One of the main working hypotheses is that vegetation-based methods for quantitative climate reconstructions will deliver precise results during longer warm intervals, particularly for the Middle/Late Eemian and Middle/Late Holocene, but that plant migration lags will hamper reconstructions for shorter warm intervals (e.g., Weichselian interstadials) and early interglacial phases. Since the sites to be analysed are positioned along a route from the Northern to the Southern Baltic Sea, it should be possible to identify migration effects if consistent age models can be applied to all profiles. Furthermore, chironomid larvae remains shall be used in samples from lacustrine sediments to gain vegetation-independent climate data. For the marine realm, in addition to dinoflagellate cysts, proxies analyzed by collaborators will allow qualitative and probably also quantitative temperature reconstructions.The Baltic Sea region is a particular interesting area for such analyses due to its intermediate position between the high latitudes and Central and Southern Europe, and also at the transition between different vegetation zones (cool temperate forest in the South and closed boreal forest in the North). High sedimentation rates in the basins where the sites have been drilled guarantee high temporal resolution and good palynomorph preservation. Pilot studies preceding and during the currently ongoing IODP-Expedition-347 onshore party indicate that palynomorph preservation is very good in fine-graded sediments from the different site, and that lacustrine sediments contain remains of aquatic insect larvae. The results of the proposed study will significantly contribute to a more detailed view on environment and climate dynamics of Northern Europe and to the understanding of climate teleconnections in the Northern Hemisphere during the past 130 000 years.