DIGITALNA ARHIVA ŠUMARSKOG LISTA
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| ŠUMARSKI LIST 9-10/2019 str. 33 <-- 33 --> PDF |
Crimean Black Pine trees of Cankiri Forests located in Cankiri and Sarıkaya Planning Units, Cankiri Forest Enterprise, Ankara Forest District Directorate. Sample trees were cut at the bottom log height (0.3 m), and the stump diameter was measured at 0.3 meters, then other measurements were made as precisely as possible at 1-meter intervals (1.3 m, 2.3 m, 3.3 m etc.) using a steel measuring tape. Furthermore, the total heights of the trees were also measured with a steel measuring tape. During these measurements, in cases where the tree trunks were oddly shaped, not cylindrical, two vertical cross-sectional diameters were measured, and their average was taken into consideration. The sample trees were randomly split into two data sets, the modeling and the validation data sets, using the random number function RANUNI implemented in the SAS statistical package (Statistical Analysis System [SAS Institute], 2009). Of those, about 85 % (306 sample trees) were used to train ANN models and fit the single and double entry volume equations and Fang et al. (2000)’s compatible volume equation, and the remaining 54 sample trees were reserved for the evaluation of the validation and testing. The summary statistics, such as the mean, standard deviations, minimum and maximum for dbh, height, and volume attributes used for modeling and validation data set, are given in Table 1. Figure 1 illustrates the diameter at breast height - volume relations of the sample trees for model fitting and validation data set. Based on these data, three-segment volumes (bottom log, sections, and top) were calculated for each sample tree, and the sum of these values provided the total stem volume. The bottom log was assumed to be cylindrical, while the top segment was accepted to have a cone-shape. As the section lengths were the same, Huber’s equation was used to define the volume of each section. The equations used to calculate tree volumes are given below. Bottom log volume; Vbottom = (1) Huber formula for sections; Vsection = (2) Top segment; Vtop = (3) |