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ŠUMARSKI LIST 3-4/2023 str. 15     <-- 15 -->        PDF

However, taking into account the stand density of the measured plots of Calabrian pine stands, the normal density value was chosen at 8.0 which is at the 90th percentile for the weighted average relative density measures (Curtis, 1982).
The number of trees in Calabrian pine stands decreases with age, and increases with increasing stand density and worsening of site index (Figure 2). At a normal stand density of 8.0 and an age of 60 years, there were 477, 622, and 749 trees per hectare for site index classes I, II, and III, respectively, while there were only 291, 379, and 457 trees per hectare for 100-year-old trees. In contrast, according to the density grades 2.0, 4.0, 6.0, 8.0, and 10.0, the number of trees per hectare in the middle class site index at 60 years of age was 261, 310, 415, 622, and 1047, and at 100 years of age, it was 159, 189, 253, 379, and 639, respectively.
The current annual volume increases in all SI classes and density grades of Calabrian pine up to 30-40 years of age and after reaching a maximum, decreases with increasing age of the stands. On the other hand, the current annual volume increases with increasing stand density and an improved site index value regardless of age (Figure 3).
Age, stand density, and improved site index all lead to an increase in total stand volume increment in Calabrian pine stands (Figure 4). Total stand volume at normal stand density of 8.0 was 622.0, 447.0 and 263.4 m3/ha at age 60 and 989.4, 713.7 and 424.4 m3/ha at age 100 for SI classes I, II