Temperature reconstructions for the last 140 years at Hohenpeißenberg using stable isotopes of wood lignin methoxyl groups

树木年轮是广泛使用的气候档案，提供百年到千年时间尺度的年度决议。木质素是主要的木材成分（高达三分之一），含有高达20%的甲氧基。最近有人提出，这些木质素甲氧基基团是一个理想的目标部分，在气候档案，如树木年轮的稳定氢同位素的调查。事实上，木材木质素甲氧基的稳定氢同位素比已被证明反映降水的稳定氢同位素比，这主要是由气候因素，如温度控制。此外，我们最近调查了来自欧洲沿着约3500 km南北样带收集的各种树木年轮的木质素甲氧基的稳定氢同位素，年平均温度（MAT）为-4至+17 ° C。我们发现MAT与木材木质素甲氧基的稳定氢同位素之间有很强的线性关系。我们使用这种关系来预测MAT随机收集的木材样本，并发现预测和观察到的MAT之间的一般协议在全球范围内的中纬度地区。因此，我们认为，稳定的氢同位素的木质素甲氧基基团可能被用来作为古温度计重建全新世中纬度温度。然而，现在需要进一步的校准研究，以更准确地访问温度对木质素甲氧基的稳定氢同位素的影响，对于较低范围的MAT。该项目的目标是利用欧洲山毛榉（Fagus sylvatica）木质素甲氧基的高分辨率稳定氢同位素年代学重建Hohenpeißenberg（德国）过去140年的年平均温度。Hohenpeißenberg被认为是一个理想的采样点，因为附近是Deutsche Wetterdienst的气象站，提供连续的气候数据记录（完整记录可追溯到公元1782年）。自有记录以来，霍亨佩森贝格的年平均气温在4.5至8.7°C之间变化很大，并且与降水的稳定氢同位素值（自1971年以来监测）有显著的相关性。在拟议的项目中，我们将调查最小年龄为120至140年的树木。我们将对15至20棵欧洲山毛榉树进行采样（每棵树三个核心），并测量树轮宽度（TRW），以验证交叉定年并评估该地区欧洲山毛榉生长的气候控制。对于稳定的氢同位素测量，将选择三个单独的欧洲山毛榉树，以避免潜在的特定地点的影响。获得的样品，它应该是可能的评估潜在的干旱（TRW）和温度的影响（稳定的氢同位素）木材形成在附近的气象站记录从南部德国。因此，该研究可能为古气候学领域的进一步应用提供有价值的温度校准。

Tree rings are widely used climate archives providing annual resolutions on centennial to millennial timescales. Lignin is a major wood component (up to one third) and contains up to 20% methoxyl groups. Recently it was suggested that these lignin methoxyl groups were an ideal target moiety for the investigation of stable hydrogen isotopes in climate archives such as tree rings. Indeed the stable hydrogen isotope ratio of wood lignin methoxyl groups has been shown to mirror the stable hydrogen isotope ratio of precipitation which is mainly controlled by climatic factors such as temperature. Moreover, we recently investigated stable hydrogen isotopes of lignin methoxyl groups of tree rings from various species collected along a ~3500 km north-south transect across Europe with mean annual temperatures (MAT) ranging from -4 to +17°C. We found a strong linar relationship between the MAT and stable hydrogen isotopes of wood lignin methoxyl groups. We used this relationship to predict MAT from randomly collected wood samples and found general agreement between predicted and observed MATs for the mid-latitudes on a global scale. Thus we suggested that stable hydrogen isotopes of lignin methoxyl groups might be used as a paleothermometer to reconstruct mid-latitude temperatures of the Holocene. However, further calibration studies are now required to more accurately access the influence of temperature on the stable hydrogen isotopes of lignin methoxyl groups for a lower range of MAT. The goal of this project is to reconstruct mean annual temperatures at Hohenpeißenberg (Germany) for the last 140 years using a high resolution stable hydrogen isotope chronology of lignin methoxyl groups in European beech trees (Fagus sylvatica). Hohenpeißenberg is considered an ideal sampling site since nearby is a weather station of the Deutsche Wetterdienst which provides a continuous record of climate data (full record dates back to 1782 AD). Since records began, the mean annual temperatures at Hohenpeißenberg show substantial variations ranging from 4.5 to 8.7°C and also show a significant correlation with stable hydrogen isotope values of precipitation (monitored since 1971). In the proposed project we will investigate trees with a minimum age of 120 to 140 years. We will sample 15 to 20 European beech trees (three cores per tree) and measure the tree ring width (TRW) to validate cross-dating and assess the climate controls of European beech growth in the region. For stable hydrogen isotope measurements three individual European beech trees will be selected to avoid potential site-specific influences. With the obtained samples it should be possible to assess the potential drought (TRW) and temperature influences (stable hydrogen isotopes) on wood formation in the close vicinity of weather station records from southern Germany. Consequently, this study would likely provide a valuable temperature calibration for further applications in the field of paleoclimatology.