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ŠUMARSKI LIST 9-10/2021 str. 45     <-- 45 -->        PDF

could be explained by significant influences of site (McCarty et al., 2017, Maissupova et al., 2017).
Actually, plantations in MU Muzljanski rit being managed on the more soil systematic units within a same section, occupy 18.43% of the area. According to previous research (Klašnja et al., 2008, Galić et al., 2011, Klašnja et al., 2012, Galić et al., 2020b) of the detected systematic units classified in eugley, the best one for growing the poplars is the β/γ gley. The systematic units of the other two eugley units (α and β gley) are unfavorable for growing the Populus x euamericana I-214, due to the reduced depth of physiologically active soil. The normal development of the root system of Populus x euamericana I-214 need physiologically active soil depth of at least 70 cm. Systematic units α and β gley can not provide sufficient physiologically active soil depth. Systematic unit area β/γ gley provide the threshold of the necessary physiologically active profile depth, allowing cultivation of Populus x euamericana I-214. Humogley in the FMU “Muzljanski rit” is characterized in enhanced soil clay (Galić et al., 2016) throughout the profile, consequently being less suitable for cultivation of the Euramerican poplar (Ivanišević et al., 2010), furthermore indicated by portion of the total sand fraction at microsites (Fuhrer et al., 2009, Bradley Pinno et al., 2010, Galić, 2010, Galić et al., 2018).
Tree diameter structures (diameter at breast height) is the first parameter indicating productivity of the plantations. At the less productive sites they reach the smaller thoracic diameters, and in the study area those were concentrated in the diameter degree of 22.5 cm (β-gley and humogley – containing silt+clay fraction). Some more favorable soil conditions at β/γ gley resulted in the largest number of trees grouped in the 27.5 cm diameter degree. A special case represents the humogley as the only soil type in the section. The largest number of trees in average was reached in diameter degree 27.5, but this was due to the small number of trees (Figure 7).
The highest quality classes are intended mainly for the production of industrial veneers, while class II has slightly lower requirements for the quality of wood than highest quality classes and it is reflected in money mainly the timber utility value (Màrkus et Mészàros, 2000, Petraš et al., 2008a). The most valuable assortments are those of 35 cm mean diameter (F logs) and 30 cm (L logs). However, the diameter structure in FMU Muzljanski rit points to the fact that the largest number of trees at the end of the rotation can be found on β gley in class I of sawlogs, whereas on the β/γ gley and humogley in L class. The minimum average volume in age from 21 to 25 years was found on humogley, 95.58 m3ha-1.