DIGITALNA ARHIVA ŠUMARSKOG LISTA

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ŠUMARSKI LIST 3-4/2023 str. 12 <-- 12 --> PDF |

by basal area, stand volume, number of trees per hectare, and stand density) are presented in Table 1. In order to create stand models, or in other words, yield tables, stand parameters like age, mean diameter, dominant height, number of trees per hectare, basal area, and volume are first estimated using data gathered from these temporary sample plots. In the second phase, stand density levels were calculated for use in density-based yield tables. When stand age and canopy height or stem analyzes were carried out in the third stage, SI tables were created based on the values for the age and heights of individual trees. Additionally, the site index of all stands in which sample plots are located were determined. In the fourth stage, stand variables such as root mean square diameter, mean height, number of trees per hectare, basal area, and standing tree volume were estimated using the appropriate regression equations as a function of stand age, site index, and degree of stand density. In the fifth phase, the volume of stand removed was estimated using appropriate regression equations as a function of stand age, SI, and degree of stand density, similar to the standing tree calculations using information on dead or dying trees obtained from observations on the sample plots. In the sixth and final stages, volume increments of the entire stand were calculated and the results were presented in tables (Yavuz et al., 2010; Kahriman et al., 2016a). In our study, the age of 10-15 trees was measured in each sample plot. The stand age (t) was calculated using the arithmetic mean of the age of trees near the root mean square diameter. The site index of the stands was calculated using the dynamic site index models obtained by Kahriman et al. (2016b and 2018) through the Generalized Algebraic Difference Approach (GADA). Among the GADA models of the Chapman-Richards (Chapman and Meyer, 1949; Goelz and Burk, 1992), Hossfeld (Cieszewski, 2001), Log-logistic (Cieszewski, 2000), Hossfeld IV (Cieszewski and Bella 1989), Lundqvist (Cieszewski, 2004), Weibull (Cieszewski, 2004), King-Pardon (Krumland and Eng, 2005), and Bertalanffy-Richards (Cieszewski, 2004), the Hossfeld model was produced the highest score based on the root mean square error (RMSE), the Akaike’s information criterion difference (AICd) (Akaike, 1974), and the Durbin-Watson (DW) tests (White, 1992). So, the Hossfeld Model was chosen as the best fit model for the Site Index. Stand density (sd) was calculated using the Relative Density Index developed by Curtis et al. (1981). The quadratic mean |