The strong impact of extreme weather conditions on the production of light rings may also explain common lack of correlation between ring-width and light rings (Szeicz, 1996; Gindl, 1999; Hantemirov et al., 2004).
The quality of the DK ring-width and isotope chronologies were tested using the expressed population signal (EPS) (Briffa and Jones [1990]), which essentially measures the level of common ring-width/isotope variation between trees.
Figure 5 Master ring-width and carbon isotope time-series for DK.
Strongly negative relationships were detected between the ring-width chronology and the monthly mean temperatures (minimum, mean, and maximum) from April to September during the growing season.
Based on the correlation between the ring width and instrumental data, a transfer function was designed and the May–July mean maximum temperature (MMT) from 1745 to 2012 was reconstructed.
The relationship between tree-ring width and tree-ring density has been intensively studied and it varies according to tree species (Bontemps et al. 2013).
The significant interactions between tree-ring width and aspect, and cambial age and aspect are illustrated in Figs. 5 and 6.
Furthermore, the correlation between ring width and wood density fluctuates between years depending on climatic and silvicultural factors (Wimmer and Downes 2003).
More detailed investigation is required in order to better understand the relationship between ring width and wood density, particularly how within-ring density components (i.e., earlywood density, latewood density, and latewood percentage) are affected by ring width.
However, unlike the density model, interaction terms with taxon were not significant, but interaction between ring width and the logarithmic transform of age was highly significant.
We showed that wood density of European beech in southwestern Germany is influenced by tree-ring age, and slightly by tree-ring width and environment, but there is a very high variability between individual trees.
