Fig. 1.

Variability in δD time series shown by boxplots. δD _i and δD_g denote time series of D abundance at intramolecular H‐C positions in tree‐ring glucose (black) and of the whole molecule (red), respectively. Data were acquired for tree‐ring glucose of Pinus nigra laid down from 1961 to 1995 at a site in the Vienna Basin (δD _i : ±SE = 5.4‰, n ≥ 3; δD_g: ±SE = 3.4‰, n ≥ 3). Outliers were removed before analysis (δD₁ to δD₃: n = 31; δD₄ and δD₅: n = 30; δD_6S: n = 26; δD_6R: n = 28; and δD_g: n = 25). Data reference: Average D abundance of the methyl group hydrogens of the glucose derivative used for NMR measurements. Insert: glucose carbon skeleton showing intramolecular locations of δD _i time series.