报告题目：Stable isotope data from tree rings in tropical and subtropical environments: applications and challenges
报 告 人： Achim Bräuning 博 士
主 持 人： 朱海峰 副研究员
时 间： 2017年10月30日（星期一）14:00-16:00
地 点： 青藏高原研究所915会议室
Dr. Achim Bräuning，德国纽伦堡-爱尔兰根大学地理系教授，我所“中科院海外特聘人才”项目高级访问学者。现任国际树轮研究会主席，欧盟COST-action FP1106计划首席。自1992年以来，他在青藏高原地区开展了大量的树轮同位素、密度、细胞结构等方面的研究，发起和参与多项与青藏高原地区气候变化有关的研究项目。
Stable carbon and oxygen isotope series from tree-ring cellulose are a frequently used proxy for paleoclimate and tree ecological studies. In tropical climates, where wood anatomical boundaries delineating annual tree rings are often unclear, they are additionally used as a proof for correct crossdating between individual tree-ring series. However, the climatic signal contained in tree-ring stable isotope series differs between climate zones: while δ18O in tree rings from temperate climates and cold high-elevation sites mirrors a temperature signal, it reflects a humidity signal in tropical climates. In tropical and monsoonal climates, the spatial representativity of tree-ring δ18O stretches over wide regions, whereas it is of more local character in the Mediterranean zone. In contrast, δ13C is mainly site dependent and reflects plant physiological responses to evapotranspiration demand. However, in semi-arid climates, tree-ring δ13C can be a good indicator for temperature conditions that determine the vapor pressure deficit of the atmosphere.
The lecture provides an overview of stable isotope signals in different climate zones and tree functional types and gives recommendations on sampling strategies in different research environments.