SummaryRetrospective information about plant ecophysiology and the climate system are key inputs in Earth system and vegetation models. Dendrochronology provides such information with large spatiotemporal coverage, and carbon‐isotope analysis across tree‐ring series is among the most advanced dendrochronological tools. For the past 70 years, this analysis was performed on whole molecules and, to this day, 13C discrimination during carbon assimilation is invoked to explain isotope variation and associated climate signals. However, recently it was reported that tree‐ring glucose exhibits multiple isotope signals at the intramolecular level (see Wieloch et al., 2024). Here, I estimated the signals' contribution to whole‐molecule isotope variation and found that downstream processes in leaf and stem metabolism each introduce more variation than carbon assimilation. Moreover, downstream processes introduce most of the climate information. These findings are inconsistent with the classical concepts/practices of carbon‐isotope dendrochronology. More importantly, intramolecular tree‐ring isotope analysis promises novel insights into forest metabolism and the climate of the past.

中文翻译：

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为碳同位素树木年代学的经典概念带来新的认识


摘要关于植物生态生理学和气候系统的回顾性信息是地球系统和植被模型的关键输入。树木年代学提供了具有较大时空覆盖范围的信息，而树木年轮系列的碳同位素分析是最先进的树木年代学工具之一。在过去的 70 年里，这种分析是对整个分子进行的，直到今天，碳同化过程中的 13C 鉴别被用来解释同位素变化和相关气候信号。然而，最近有报道称，树轮葡萄糖在分子内水平上表现出多种同位素信号（参见 Wieloch等人，2024 年）。在这里，我估计了信号对全分子同位素变化的贡献，并发现叶和茎代谢的下游过程都比碳同化引入更多的变异。此外，下游过程引入了大部分气候信息。这些发现与碳同位素树轮年代学的经典概念/实践不一致。更重要的是，分子内树环同位素分析有望为森林代谢和过去的气候提供新的见解。