Scientific Merits and Analytical Challenges of Tree-Ring Densitometry

J. Björklund, G. von Arx, D. Nievergelt, R. Wilson, J. Van den Bulcke, B. Günther, N. J. Loader, M. Rydval, P. Fonti, T. Scharnweber, L. Andreu-Hayles, U. Büntgen, R. D'Arrigo, N. Davi, T. De Mil, J. Esper, H. Gärtner, J. Geary, B. E. Gunnarson, C. HartlA. Hevia, H. Song, K. Janecka, R. J. Kaczka, A. V. Kirdyanov, M. Kochbeck, Y. Liu, M. Meko, I. Mundo, K. Nicolussi, R. Oelkers, T. Pichler, R. Sánchez-Salguero, L. Schneider, F. Schweingruber, M. Timonen, V. Trouet, J. Van Acker, A. Verstege, R. Villalba, M. Wilmking, D. Frank

Research output: Contribution to journalReview articlepeer-review

58 Scopus citations


X-ray microdensitometry on annually resolved tree-ring samples has gained an exceptional position in last-millennium paleoclimatology through the maximum latewood density (MXD) parameter, but also increasingly through other density parameters. For 50 years, X-ray based measurement techniques have been the de facto standard. However, studies report offsets in the mean levels for MXD measurements derived from different laboratories, indicating challenges of accuracy and precision. Moreover, reflected visible light-based techniques are becoming increasingly popular, and wood anatomical techniques are emerging as a potentially powerful pathway to extract density information at the highest resolution. Here we review the current understanding and merits of wood density for tree-ring research, associated microdensitometric techniques, and analytical measurement challenges. The review is further complemented with a careful comparison of new measurements derived at 17 laboratories, using several different techniques. The new experiment allowed us to corroborate and refresh “long-standing wisdom” but also provide new insights. Key outcomes include (i) a demonstration of the need for mass/volume-based recalibration to accurately estimate average ring density; (ii) a substantiation of systematic differences in MXD measurements that cautions for great care when combining density data sets for climate reconstructions; and (iii) insights into the relevance of analytical measurement resolution in signals derived from tree-ring density data. Finally, we provide recommendations expected to facilitate futureinter-comparability and interpretations for global change research.

Original languageEnglish (US)
Pages (from-to)1224-1264
Number of pages41
JournalReviews of Geophysics
Issue number4
StatePublished - Dec 1 2019


  • X-ray densitometry
  • anatomical density
  • blue intensity
  • maximum latewood density (MXD)
  • microdensitometry
  • paleoclimatology

ASJC Scopus subject areas

  • Geophysics


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