DIGITALNA ARHIVA ŠUMARSKOG LISTA
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ŠUMARSKI LIST 1-2/2018 str. 43     <-- 43 -->        PDF

At the stand level, the diameter increment of the 100 and 400 thickest trees in the stand in the period between the ages of 41 and 50 was higher by 36 to 42% than the diameter increment in the period between the ages of 33 and 40. The statistical significance was weak (p <0.05) to high (p <0.001). The current annual height increment of the representatives was lower in the period between the ages of 41 and 50, by an average of 26-27%, than in the period between the ages of 33 and 40 and the differences were highly statistically significant (Table 6, Graph 6).
The current diameter increment of the aspirants in the specified periods (41-50 and 33-40 years of age) was within the range of the diameter increment of dominant (D100 and D400) trees in the stand (Table 7). The diameter increment of the aspirants was 29.1% higher between the ages of 41 and 50 than between the ages of 33 and 40. In the 400 and 100 thickest trees in the stand, the current diameter increment was 36% or 42% higher in the period between the ages of 41 and 50, compared to the period between the ages of 33 and 40. When calculating the current diameter increment for the collective of all trees, calculation is different because there is a different number of trees in each period, so the current diameter increment in the period between the ages of 41 and 50 was 68% higher compared to the previous period  when the number of trees on the experimental plot was almost twice bigger (Table 7).
In the period between the ages of 33 and 40, the remaining trees (1978 trees per hectare) achieved a total volume increment of 177.68 m3∙ha-1, or an average of 22.21 m3∙ha-1∙year-1, which is 29% higher than the attained cutting yield at the age of 32. In the period between the ages of 41 and 50, the remaining trees (1,067 trees per hectare) achieved a total volume increment of 257.3 m3∙ha--1, or an average of 25.73 m3∙ha-1∙year-1, which is 81% higher than the realized cutting yield at the age of 40. In the period between the ages of 33 and 40, 311 aspirant trees per hectare  (15.7% of the total number of trees) had a share of about 32% in the current increment of basal area and volume, while in the period between the ages of 41 and 50, these 311 aspirant trees per hectare (29.1% of the total number of trees) had a share of 45 to 46% (Table 7). In the period between the ages of 41 and 50, almost half the total number of trees achieved a 15.8% higher volume increment per hectare than in the period from 33 to 40, and the same collective of aspirant trees (311 trees per hectare) achieved a 68.5% higher current volume increment (Table 7).
The total stand volume increment recorded on the experimental plot at the age of 40 amounted to 561.85 m3·ha-1, and the average annual increment was 14.05 m3∙ha-1∙year-1. The share of the previous increment in the stand before the age of 40 amounted to 137. m3·ha-1 or 24.4% of the total volume increment. The total volume increment measured at the age of 50 amounted to 819.1 m3·ha-1, the average annual increment was 16.38 m3∙ha-1∙year-1, and the share of the previous increment amounted to 279.4 m3·ha-1 or 34.1% of the total recorded volume increment.
The effect of thinning on slenderness of trees and stability of stand – Utjecaj prorjeda na stupanj vitkosti stabala i stabilnost sastojine
The degree of slenderness of dominant trees, obtained on the basis of the detailed analysis of dominant trees (D100 and D400), had  minimum values in the period between the ages of 15 and 26 and amounted to 60-70. After this period, the degree of slenderness showed an increase and reached the value of approximately 80 at the age of 32 in both trees. At the age of 40, the degree of slenderness of the tree representing the 100 thickest trees was 80, and 90 of the tree representing the 400 thickest trees. At the age of 50, the average degree of slenderness of dominant trees, obtained based on the measurement of growth elements, corresponded to the degree of slenderness obtained by a detailed analysis of trees at the age of 40 (Graph 7).
The cumulative curves of slenderness for the total number of trees show that at the age of 32 less than 8% of trees had the degree of slenderness below 80, only 2% at the age of 40, and 8% of trees at the age of  50. Furthermore, 53% of trees had the degree of slenderness above 100 at the age of 32, 63% at the age of 40 and 36% at the age of 50 (Graph 8 left).
At  the age of 32, 50% of the aspirant trees had the degree of slenderness below 80, less than 15% at the age of 40, and less than 30% at the age of 50. However, all aspirant trees had the degree of slenderness below 90 at the age of 32, 50%