Terrestrial ecosystem response to climate variability during MIS 12-11 and MIS 19 in SE Europe based on high-resolution pollen analysis of Lake Ohrid ICDP core sediments.

深入了解第四纪极端冰期和间冰期的陆地生态系统和气候演化。该项目旨在为欧洲东南部的海洋同位素阶段（MIS） 12-11和（作为后续提案的新元素）19c生成新的陆生花粉记录。该项目的目标是通过对2013年通过ICDP钻井回收的Ohrid湖（巴尔干半岛西南部）岩心材料进行高分辨率孢粉学研究来实现的。在项目的头两年，工作包(1)和(2)产生了(i) MIS 11的百年尺度（~450年）孢粉学记录，其中花粉（约500粒）、孢子和藻类的计数量很高，以及基于花粉的温度和降水重建；（ii）欧洲第一个百年尺度（~ 400-800年）孢粉学记录。将孢粉学数据与奥赫里德湖科学小组合作伙伴提供的沉积学和地球化学信息相结合，并与区域代理记录进行比较，有助于完善当前对MIS 12-11期间东南欧洲及其他地区陆地生态系统和气候演变的认识。迄今为止（即，在23个项目月之后），我们最重要的发现包括以下证据：(i)在完全间冰期条件下~405 ka发生的一次强烈冷却事件，表明南欧千年尺度气候变率的开始比最温暖的MIS 11c次阶段结束早~7年，比海洋领域早；（ii）在MIS 12期间，喜热树木的短暂扩张，表明陆地生态系统在全冰期对Dansgaard-Oeschger （D-O）样变暖事件的敏感响应；(3)奥赫里德湖流域在MIS 12和MIS 11期间均存在珍稀树种，支持该地区作为更新世树木避难所的观点。第三个项目年将专门用于工作包(3)，这将产生：(i)提高MIS 12花粉记录的时间分辨率，从而更好地限制检测到的d - o样事件的时间、速度和性质；（ii）作为对原始建议的补充，在间冰期MIS 19c中发现了一个新的百年尺度的花粉记录，该间冰期与MIS 11一起被认为是全新世的轨道相似物；（iii）项目成果的全面综合。具体而言，MIS 19c新增加的分量将首次允许基于来自同一地点（即相同地理边界条件下）的三个间冰期（MIS 1、11c和19c）的高分辨率花粉记录来约束欧洲陆地生态系统对低偏心强迫的响应。总而言之，该项目将为第四纪关键时期东地中海地区短期气候和环境变化的性质提供新的见解。

To gain detailed insight into the terrestrial ecosystem and climate evolution under extreme glacial and interglacial intervals of the Quaternary. the project aims to generate new terrestrial pollen records for Marine Isotope Stages (MIS) 12–11 and (as a new element within this follow-up proposal) 19c in SE Europe. The project goals are achieved via high-resolution palynological study of core material from Lake Ohrid (SW Balkan Peninsula) that has been recovered through ICDP drilling in 2013. During the first two project years, Work Packages (1) and (2) have yielded (i) a centennial-scale (~450 years) palynological record for MIS 11 with high counting sums for pollen (>500 grains), spores and algae, as well as pollen-based temperature and precipitation reconstructions; and (ii) the first centennial-scale (~400–800 years) palynological record for MIS 12 in Europe. The integration of the palynological data with sedimentological and geochemical information generated by collaboration partners within the Lake Ohrid science party, and comparison with regional proxy records has helped to refine the current understanding of terrestrial ecosystem and climate evolution during MIS 12–11 in SE Europe and beyond. To date (i.e., after 23 project months), our most important findings comprise evidence for (i) a strong cooling event at ~405 ka during full interglacial conditions, suggesting that the onset of millennial-scale climate variability in Southern Europe occurred ~7 kyrs before the end of the warmest sub-stage MIS 11c and earlier than in the marine realm; (ii) a transient expansion of thermophilous trees during MIS 12, suggesting a sensitive response of terrestrial ecosystems to Dansgaard-Oeschger (D-O)-like warming events during full glacial conditions; (iii) the presence of rare tree taxa in the Lake Ohrid catchment both during MIS 12 and 11, supporting the notion that the area acted as a Pleistocene tree refugium. The third project year will be dedicated to Work Package (3), which will yield (i) an increased temporal resolution for the MIS 12 pollen record, allowing to better constrain the timing, tempo and nature of the detected D-O-like events; (ii) as an added value to the original proposal, a new centennial-scale pollen record for MIS 19c, an interglacial also considered a close orbital analogue for the Holocene alongside with MIS 11; and (iii) an overall synthesis of the project results. Specifically, the newly added component of MIS 19c will allow for the first time to constrain terrestrial ecosystem response to low eccentricity forcing in Europe based on high-resolution pollen records from three interglacials (MIS 1, 11c and 19c) from the same site (i.e., under identical geographical boundary conditions). In summary, the project will provide new insights into the nature of short-term climate and environmental change in the Eastern Mediterranean region during critical periods of the Quaternary.