The frequency of ray and axial parenchyma versus tree-ring width in silver fir (Abies alba Mill.)

Abstract

Key message

Ray and axial parenchyma frequency, observed in cross-sections of mature Abies alba trunks is not related to tree-ring width.

Abstract

We studied the relationship between tree-ring width and frequency of ray and axial parenchyma of mature silver fir (Abies alba Mill.) to assess whether the selected wood-anatomical variables contain complementary or redundant environmental or physiological information. Cross-sections from 400 tree rings were analysed by transmitted light microscopy and image analysis. We found no relevant correlation between the tree-ring width, expressed by the number of cells along three radial files, and the number of rays (i.e. the sum of all rays, where the partial rays are present along half of the tree-ring width) per unit area. Despite statistically significant correlation, more or less constant number of rays (on average between 6 and 7) over the whole range of the tree-ring widths was observed. Similarly, we did not find a significant correlation between the number of axial parenchyma cells and the tree-ring width. A lack of relevant association between the number of rays or axial parenchyma cells per unit area and the tree-ring width indicates that the studied wood-anatomical variables may contain environmental or physiological information different from that stored in tree-ring widths. However, further wood anatomical analyses of long tree-ring series are needed to evaluate the potential of ray parenchyma as a climate proxy.