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识别和量化波罗的海地区从Eemian到全新世的生态系统和气候动态。这一目标将通过IODP第347次考察期间从波罗的海五个地点获取的千年至百年尺度的地貌记录来实现。对花粉和孢子进行分析，以评估陆地生态系统和气候变化。通过对花粉组合的最近生活亲属法和现代类似物技术的应用，将产生陆地领域的定量降水和温度数据。对于海洋沉积物，应在与陆地形态相同的样品中分析鞭毛藻囊和其他海洋代用物，以定性地评估海洋领域同期的温度和盐度变化。其中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精确的结果，特别是在Eemian中期/晚期和全新世中期/晚期，但是植物迁移滞后将阻碍较短的温暖间隔（例如Weichselian间冰期）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，如果一致的年龄模型可以应用于所有剖面，就有可能确定迁移的影响。此外，在湖泊沉积物样品中，摇尾蛾幼虫仍保持应使用，以获得与植被无关的气候数据。对于海洋领域，除了鞭毛藻囊肿，合作者分析的代理将允许定性和可能也定量的温度重建。波罗的海地区是进行这种分析的一个特别有趣的地区，因为它处于高纬度地区与中欧和南欧之间的中间位置，而且处于不同植被带之间的过渡地带（南部的凉爽温带森林和北部的封闭北方森林）。在钻探地点所在的盆地中，高沉积速率保证了高时间分辨率和良好的地貌保存。在目前正在进行的IODP-Expedition-347岸上团队之前和期间进行的试点研究表明，在不同地点的细分级沉积物中，生物形态保存得非常好，湖泊沉积物中含有水生昆虫幼虫的遗骸。提出的研究结果将有助于更详细地了解北欧的环境和气候动力学，并有助于了解过去13万年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.