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ŠUMARSKI LIST 5-6/2019 str. 40     <-- 40 -->        PDF

Control), 10% (Light), 25% (Moderate) and 40% (Strong) of basal area in a hectare of the experimental plots, sample plots were established by applying three thinning intensities with four replications. The plots are 900 m2 (30 m x 30 m) in size. The procedures determined for each plot were performed on the entire plot. The measurements were performed in an area of 400 m2 (20 m x 20 m). 5 m-wide area surrounding this region was left as an isolation zone, and no measurement was performed in this area.
200-250 ha-1 (8-10 tree/measurement area) future trees suitable for managerial purposes with a regular development, a plump stem, and asymmetrical crown were identified in each experimental plot. The stems, the cramped stems, forked stems and whippers in the predominant layer that pressurize the future trees in the plots where thinning was applied and the dead or diseased individuals in the intermediate and lower layers were excluded from the plot according to thinning intensity. In these plots, the individuals living in the intermediate and lower layers were protected as much as possible. In the control plots, all of the trees were protected and no treatment was applied. For the thinning process, trees were selected and labeled outside the 2010 vegetation period. All of the trees that would remain in the measurement plot were labeled before thinning. The diameters and heights of all trees in the experimental plots were measured. Second measures were performed at the end of 2012 to determine the possible effects of the thinnings. The basal area volumes were calculated from the diameter values of trees measured at 1.30 m height. The value found was multiplied by hectare conversion coefficient and the amount of basal area in hectare was determined. The determination of the volume of experimental plots was performed in two stages. The trees removed by thinning treatment were cut, diameter measurements were performed with 0.30 m, 1.30 m and 2 m intervals in these trees, and the stem volumes were calculated by section method. In the calculation of volume, the stem was divided into three separate sections including stump, sections and end pieces, and the total stem volume was calculated by their addition. It was assumed that the stump was cylindrical and the end piece was conical. The “Huber” formula was used in the volume of the section. The volume values determined by using the measurements performed in the trees cut were associated with the diameters, and the tree volume table was created. The total volumes of experimental plots were determined by using the volume table to be created because the diameters of all trees were measured in the experimental plots. The stem volumes of trees were calculated for each experimental area using the diameter measurements of trees. Accordingly, the following formulas were developed for each experimental area (Yılmaz et al. 2016).
Yeşiltepe Experimental area,                  (R2=0.956)
Vakfıkebir Experimental area,                  (R2=0.932)
In the equation, V represents the barked stem volume (m3) and d represents the basal diameter (cm). According to this equation, in order to determine the stem volume of a tree, there is a need for the diameter values of that tree (Figure 2).
Analyses of variance (ANOVA) were performed to determine the effects of thinning intensity on growth and increments (%) in the plantations (P < 0.05). Data analyses were at the stand level. The normality distribution test was controlled for all variables before ANOVA. Because no indication of abnormality was found, there was no need to transform the variables before evaluation. Where significant differences occurred, treatment means were separated by Duncan’s new multiple range test (P < 0.05).
The values of pre-thinning average diameter (D), height (H), basal area (BA) and stem volume of plantations were compared according to thinning intensities (Table 2). Accordingly, statistically significant differences were found between all measurement parameters in both plantation areas (p<0.05). This means that experimental plots are not homogeneous. Comparisons were performed over the relative increments (%) to be able to better see the effect of thinnings on measurement parameters.
In both experimental plots, the highest RDI occurred in the plots where strong thinning was applied (Figure 4). In terms of RDI, in Vakfıkebir experimental plot, the control and