DIGITALNA ARHIVA ŠUMARSKOG LISTA
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| ŠUMARSKI LIST 9-10/2023 str. 41 <-- 41 --> PDF |
(Schumacher and Hall 1933; Meyer 1941; Newnham 1967; Spurr 1952; Laar and Akça 2007; Pranjić and Lukić 1997; Takata 1958; Emrović 1960; Banković and Pantić 2006; Kaufmann 2001; Eriksson 1973; Johansson 2005). The tested models are shown in Table 2. To compare and analyze the usability of regression models, the criteria (Draper and Smith 1997; Wackerly et al. 2008; Chicco et al. 2021; Burnham and Anderson 2002; Symonds and Moussalli 2011) shown in table 3 were used. In addition to the criteria listed in table 3, the significance of the differences were tested using the paired sample t-test (the dependent sample t-test) between the real and estimated merchantable wood volumes of the trees, by diameter classees and in total. The percentages of deviations estimated from the real volumes by diameter classes and in total were determined as an important indicator of the applicability of the model, according to the formula (Bruce 1920, according to Pranjić and Lukić 1997): vf - tree volume estimated by function vr - real tree volume RESULTS AND DISCUSSION REZULTATI I RASPRAVA The diameter at breast height (d1.3) ranged from 10.15 to 79.60 cm and height (h) from 8.38 to 38.65 m. Based on the distribution of trees, according to diameter classes (5-centimeter-wide diameter classes), it can be stated that there is a relatively small number of trees that are thicker than 70 cm. In other diameter classes, the number of trees is greater than 100, that is, in the interval from 111 to 316, with an average of 200 trees. According to Banković and Pantić (2006), based on some research (Germany, Czech Republic, Slovakia, Romania, Russia...), it was concluded that the optimal number of measured trees in each diameter class should not be less than 100 and more than 350. This is completely fulfilled, except in the highest diameter classes (> 70 cm). Based on the forest inventory data on large areas in Bosnia and Herzegovina (2006 - 2009), it is evident that there is a relatively small number of sessile oak trees with a thickness of 70 cm to 80 cm in high forests, which is expected, considering the way of management. The real volume of trees is in the interval from 0.04 to 8.99 m3. The variation of tree volume as a dependent variable is significantly greater than the variation of diameter at breast height, diameter at 7 meters height, crown height above ground, and tree |