Water δD and δ¹⁸O were measured in a secondary Chinese pine forest at Yanshan Station in northern China. Precipitation was analysed directly. Water was extracted from field soil, twig and leaf samples by cryogenic vacuum distillation at 180 °C for 3 h (West et al., 2006; Orlowski et al., 2013). A TLWIA-912 liquid-water isotope analyser was used to measure each sample six times; the last four injections were averaged. Values are reported in ‰ relative to VSMOW, with analytical precision of ±0.3‰ for δ²H and ±0.1‰ for δ¹⁸O. Soil and plant reference experiments quantified extraction offsets under different conditions (Diao et al., 2022). Methanol standards characterised spectral interference in plant-water analysis (Martín-Gómez et al., 2015). The workbook contains sample measurements before extraction-bias correction.

Diao, H., Schuler, P., Goldsmith, G. R., Siegwolf, R. T. W., Saurer, M., & Lehmann, M. M. (2022). Technical note: On uncertainties in plant water isotopic composition following extraction by cryogenic vacuum distillation. Hydrology and Earth System Sciences, 26, 5835–5847. https://doi.org/10.5194/hess-26-5835-2022

Martín-Gómez, P., Barbeta, A., Voltas, J., Peñuelas, J., Dennis, K., Palacio, S., et al. (2015). Isotope-ratio infrared spectroscopy: a reliable tool for the investigation of plant-water sources? New Phytologist, 207, 914–927. https://doi.org/10.1111/nph.13376

Orlowski, N., Frede, H.-G., Brüggemann, N., & Breuer, L. (2013). Validation and application of a cryogenic vacuum extraction system for soil and plant water extraction for isotope analysis. Journal of Sensors and Sensor Systems, 2, 179–193. https://doi.org/10.5194/jsss-2-179-2013

West, A. G., Patrickson, S. J., & Ehleringer, J. R. (2006). Water extraction times for plant and soil materials used in stable isotope analysis. Rapid Communications in Mass Spectrometry, 20, 1317–1321. https://doi.org/10.1002/rcm.2456