DIGITALNA ARHIVA ŠUMARSKOG LISTA
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| ŠUMARSKI LIST 5-6/2018 str. 45 <-- 45 --> PDF |
orchard, while it had recently begun in middle-aged, and had been ongoing for nine years in old seed orchard. While the middle-aged and young seed orchards were established at 5×5 spacing, the old seed orchard was established at the 8×8 spacing generally used in Turkish red pine seed orchard. In the young seed orchard, the terminal shoots were pruned, while in the middle-aged seed orchard, the top nodes which are the points on stem originating branches were pruned. The same treatment was applied in these seed orchards in 2012. On the other hand, in the old seed orchard, three and five nodes were pruned in 2008, and no pruning was performed in 2012 (Table 2). In all three seed orchards, a randomized complete block design with five blocks was used. In each block, 7×7 pruned and unpruned ramets were taken randomly, the outer 2 rows were kept as buffer, and 9 ramets (3×3) in the middle were included into the study. The heights of the ramets were measured before and after pruning, and the diameter at breast height and crown diameter were then measured bi-directionally. A year after pruning, all conelets and cones were counted, and the height, diameter at breast height and crown diameter values were all measured in nine ramets at the center of all pruned and unpruned plots. Measurements and observations continued for two in the old seed orchards, and for four years in the young and middle-aged seed orchards. Conelet and cone numbers were transformed logarithmically before the analysis of variance. Furthermore, assuming that the top volume of each ramets has a conic shape, the volume index was calculated using the formula . In the formula, V represents the volume index, r represents the crown radius, and h represents the height of the tree. Volume index and diameter at breast height were used as covariates in the model. The statistical model for the analysis of variance is given below: Yijkl: the observed value for tree l , in block i, at treatment j, of year k, µ: general mean, A1: diameter at breast height regression coefficient, Dijkl: diameter at breast height for tree l, in block i, at treatment j, of year k, A2: volume index regression coefficient, Vijkl: volume index for tree l, in block i, at treatment j, of year k, Bi : block i, Tj : treatment j, zk: year k, Tzjk: year-treatment interaction, and eijkl: error. In this model, the year was considered as a random effect, while the block and treatment were taken as fixed effects. The SAS 9.0 statistical software was used for analysis (SAS Institute Inc., 2002). |