δ²H, δ¹³C and δ¹⁸O from whole wood, α-cellulose and lignin methoxyl groups in Pinus sylvestris: a multi-parameter approach

Abstract

Novel tree ring parameters – δ¹³C and δ²H from methoxyl groups – have been developed to reconstruct palaeoclimate. Tests with δ¹³C and δ¹⁸O derived from whole wood and cellulose samples, however, indicated differences in the isotopic composition and climate signal, depending on the extracted wood component. We assess this signal dependency by analysing (i) δ¹³C and δ¹⁸O from whole wood and cellulose and (ii) δ¹³C and δ²H from methoxyl groups, using Pinus sylvestris L. growing near Altenkirchen (Germany). Results indicate significant correlations among the time series derived from whole wood, cellulose, and lignin methoxyl groups. Compared with the whole wood samples, δ¹³C from methoxyl groups showed a different and overall lower response to climate parameters. On the other hand, δ²H from methoxyl groups showed high correlations with temperature and was also correlated with ring width, indicating its potential as a temperature proxy. Isotope time series with the highest correlation with climatic parameter were: (i) whole wood and cellulose δ¹³C with growing season precipitation and summer temperature; (ii) methoxyl groups with spring precipitation; (iii) whole wood and cellulose δ¹⁸O correlates with annual evapotranspiration and water balance; and (iv) methoxyl group δ²H with spring temperatures. These findings reveal that multiple climate elements can be reconstructed from different wood components and that whole wood proxies perform comparably to cellulose time series.

Keywords:

• carbon-13
• climate
• dendroclimatology
• hydrogen-2
• isotope ecology
• oxygen-18
• pine trees
• tree rings
• wood components

Acknowledgements

The authors gratefully acknowledge Dorethee Krieger and Bernhard Backes (University of Trier) for the TC/EA-IRMS measurements. We also would like to thank Hans-Werner Schröck (FAWF Trippstadt) for providing wood samples and climate data. We also would like to thank two anonymous reviewers.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The study was supported by the EU-project ForeSTClim (Transnational Forestry Management Strategies in Response to Regional Climate Change Impacts). Frank Keppler and Markus Greule were supported by the DFG (KE 884/6-1 and KE 884/6-2).