Development and analyses of tree-ring chronologies to reconstruct prehistoric environmental conditions in West and Central Europe

近代树木、历史木材、亚化石树木和考古木材的年轮构成了古科学最重要的基础之一。没有其他具有年度分辨率的环境档案涵盖整个全新世。树木年轮宽度、稳定同位素和放射性同位素的特征可用于气候和环境重建。但它们也可以用于确定木器发现和其他重要档案（如冰芯、洞穴或沉积物）的精确年代。由此产生的气候重建和精确的树木年代测定使考古学家和历史学家能够更好地评估过去人们的生活条件，并质疑环境对经济和社会的影响。因此，现代气候变化可以追溯到它们的全新世背景。因此，从全新世到晚冰期，树木年轮年表的持续扩展是特别重要的。欧洲的条件很理想。在世界范围内，霍恩海姆大学（University of Hohenheim）历时12460年的“德国南部树木年轮年表”（Becker et al. 1982, Friedrich et al. 2004）是独一无二的，尽管这些数据从未完整发表过。我目前在德国科学基金会资助的项目（SP 437/16- 1,2015年2月1日- 2018年1月31日）中取得的成就是开发高复制的中欧橡树年轮年表，以缩小差距，并将其作为水文气候重建的基础。出乎意料的是，我们成功地将来自14个欧洲树木考古实验室的橡树年轮宽度系列数据库汇编成一个单一的数据库。这是一个全球独一无二的新数据集，包含了过去7500年里来自4815个地点的63.730个树木年轮宽度测量值。到目前为止，进行了仔细的加工，协调和质量控制。然而，在当前和即将结束的项目中无法完成对这个广泛数据集的全面分析。因此，需要将该项目延长两年进行分析和水文气候重建。正在进行的实验揭示了树木年轮宽度和地下水波动之间惊人的密切关系。这是一种新的认识，我们希望继续进行分析，以重建过去7500年来地下水的历史波动。因此，将项目延长两年是合理的，预计将取得非常有希望的成果。

Tree rings of recent trees, historical timbers, subfossil trees and timbers from archaeological context constitute one of the most important fundament of Paleosciences. No other environmental archive with annual resolution covers the entire Holocene. The signatures of tree-ring widths, stable isotopes and radioisotopes can be used for climate and environmental reconstructions. But they also serve for precise dating of wooden finds and other important archives such as ice cores, speleothems or sediments.Resulting climate reconstructions and precise dendrochronological datings allow archaeologists and historians to better assess the living conditions of people in the past and to question environmental impacts on economy and society. The modern climate change can thus be retrospectively placed in their Holocene context. Therefore, a consistent expansion of tree-ring chronologies over the Holocene until the Late Glacial is of particular importance. The conditions are ideal in Europe. Worldwide, the "South German tree-ring chronology" of the University of Hohenheim spanning the last 12,460 years (Becker et al. 1982, Friedrich et al. 2004) is unique, although the data were never published in full.Achievements during my current project funded by the German Science Foundation (SP 437/16-1, 1.2.2015 – 31.1.2018) were to develop high replicated Central European oak tree-ring chronologies to close gaps, and to use them as a basis for hydro-climatic reconstructions. Unexpectedly, we have succeeded in compiling a previously unpublished database of oak tree-ring width series from 14 European dendro-archaeological laboratories in a single database. This is a worldwide unique new dataset comprising a total of 63.730 tree-ring width measurements from 4.815 sites covering the last 7.500 years. So far, a careful processing, harmonization and quality control was performed. However, a comprehensive analysis of this extensive dataset could not be accomplished in the current and now ending project. Therefore, an extension of the project by two years for the analysis and hydro-climate reconstructions is needed. Ongoing experiments revealed surprisingly close relationships between tree-ring width and groundwater fluctuations. This is new knowledge, and it would be desirable to continue the analyses with the aim to reconstruct historical groundwater fluctuations over the last 7.500 years. The project extension by two years is therefore justified and highly promising results are expected.