Effect of stand density index on selected features of macrostructure and density of Norway spruce (Picea abies (L.) Karst.) wood

The aim of the study was to determine the influence of stand density index on the tree-ring width, latewood proportion and wood density for Norway spruce. Study sites were located as follows: 12 within the north-eastern species range in Poland, 7 in the south-western range, in the Sudety Mts., and 9 in the Carpathians (southern range). Clustering stands according to their stand density index, 10 data groups were established: stand density index values from 0.3 to 1.2. The study plots were 100x100 m squares. On each plot 15 trees were chosen and increment cores were sampled using the Pressler borer. The smoothed cores served for measuring the width of annual rings, latewood zones and the share of latewood as well as for determination of relative wood density. The performed analyses indicate that mean tree-ring width was the highest in trees from stands with density index from 0.3 to 0.8 (with the exception of 0.7), whereas the it was gradually decreasing in stands with index higher than 0.9. The statistically significant differences between the analyzed stands were observed (p<0.0001). The analysis of the influence of stand density index and the width of annual rings revealed significant, negative weak correlation (r=-0.242, p<0.001). In turn, the latewood proportion was the highest in trees from stands characterised by the highest stand density index and the lowest in trees from stands with the lowest one. The differences between analyzed groups of stands were statistically significant (p<0.0001), as well as the correlation which was significant, positive and weak (r=0.269, p<0.001). Wood density was the highest in trees from stands with the highest stand density index (1.1 - 363 kg/m(3) i 1.2 - 365 kg/m(3)) as well as in those from stands characterised by 0.7 density index (369 kg/m(3)). Significant differences were observed (p<0.0001) only between stand density index 0.3-0.7 and 0.7-0.8. Significant correlation was not observed.