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Simulating oxygen isotope ratios in tree ring cellulose using a dynamic global vegetation model

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Keel Sonja G., Joos Fortunat, Spahni Renato, Saurer Matthias, Weigt Rosemarie B., Klesse Stefan,
Project iTREE-Long-term variability of tree growth in a changing environment - identifying physiological mechanisms using stable C and O isotopes in tree rings.
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Original article (peer-reviewed)

Journal Biogeosciences
Volume (Issue) 13(13)
Page(s) 3869 - 3886
Title of proceedings Biogeosciences
DOI 10.5194/bg-13-3869-2016

Open Access

URL http://doi.org/10.5194/bg-13-3869-2016
Type of Open Access Publisher (Gold Open Access)

Abstract

Records of stable oxygen isotope ratios in tree rings are valuable tools to reconstruct past climatic conditions and investigate the response of trees to those conditions. So far the use of stable oxygen isotope signatures of tree rings has not been systematically evaluated in dynamic global vegetation models (DGVMs). DGVMs integrate many hydrological and physiological processes and their application could improve proxy-model comparisons and the interpretation of oxygen isotope records. Here we present an approach to simulate leaf water and stem cellulose δ 18 O of trees using the LPX-Bern DGVM (LPX-Bern). Our results lie within a few per mil of measured tree ring δ 18 O of 31 different forest stands mainly located in Europe. Temporal means over the last 5 decades as well as interannual variations for a subset of sites in Switzerland are captured. A sensitivity analysis reveals that relative humidity, temperature, and the water isotope boundary conditions have the largest influence on simulated stem cellulose δ 18 O, followed by all climatic factors combined, whereas increasing atmospheric CO 2 and nitrogen deposition exert no impact. We conclude that simulations with LPX-Bern are useful for investigating large-scale oxygen isotope patterns of tree ring cellulose to elucidate the importance of different environmental factors on isotope variations and therefore help to reduce uncertainties in the interpretation of δ 18 O of tree rings.
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