Wood increment cores of 15 Quercus robur tree individuals were taken. Dendro-dated late wood from tree rings of 5 individuals was dissected (not pooled). After cellulose extraction and homogenization, 18O/16O-ratios of annually resolved samples were determined by Isotope Ratio Mass Spectrometry (IRMS). Time series of 18O/16O are given as delta-values versus VSMOW. Details can be found in the downloadable “data description” file.

An annually resolved chronologies of oxygen isotopes from five living oak (Quercus robur) trees have been measured from tree ring cellulose covering up to the last 180 years (1836CE – 2020CE). This tree-ring stable isotope data set was established within the ‘Terrestrial Environmental Observatories’ (TERENO) of the Helmholtz Association. The site “Lake Tiefer See” is subject to the TERENO monitoring activities at the Northeast German Lowland Observatory coordinated by the GFZ German Research Centre for Geosciences in Potsdam. The data set comprises the δ18O records with respect to the international VSMOW standard.

Lake Tiefer See (53°350 N, 12°320 E) is located 90 km NNW of Berlin in the morainic terrain of the NE-German Polish Basin. It is part of in the N–S trending Klocksin Lake Chain. The sampled trees are growing at the southern shore of the lake.

Fifteen co-dominant Quercus robur tree individuals were cored at about 1.3m above ground from two opposite positions using an increment corer of 5 mm diameter (Suunto, Finland or Mora, Sweden).