Effect of wide spacing on increment and branch properties of young Norway spruce

Berlin

2006

S. 239-248

4 Abb., 3 Tab., zahlr. Lit. Ang.

Artikel aus einer ZeitschriftUnselbständiges Werk

200136557

The effects of stand density on increment and branch properties were studied in three spacing experiments of Norway spruce [Picea abies (L.) Karst.]. The stand densities ranged from 350 stems 1/ha, regarded as open-grown trees, up to 1,600 stems 1/ha, corresponding to the density recommended for forestry practice. Properties of all the branches were measured from the stem apex downwards. The study material included a total of 5,661 branches from 45 trees. Increasing stand density resulted in a decrease in radial increment as well as shorter and narrower crowns, but it had no effect on height increment. The average number of spike knots per tree was 0.87, 0.27, and 0.33 in densities of 350, 700 and 1,600 1/ha, respectively. Additionally, in the widely spaced stands of 350 stems 1/ha, the fraction of trees having spike knots was high (over 50%). At a density of 1,600 1/ha, the sample trees had somewhat less branches in a whorl compared with the more widely spaced plots. The most pronounced effect of stand density was the increase in branch diameter with decreasing stand density. At a density of 350 1/ha, the maximum branch diameter of all the sample trees exceeded the diameter limit of quality class B in the European quality requirements for round wood. The results give some indication that trees subjected to severe competition would produce smaller branches per unit of crown projection area. However, the possibilities for reducing branch dimensions relative to stem and crown size through competition appear quite restricted.