نوع مقاله : مقاله کامل علمی پژوهشی
نویسندگان
1 دانشیار، پژوهش، مؤسسۀ تحقیقات جنگلها و مراتع کشور، سازمان تحقیقات، آموزش و ترویج کشاورزی، تهران، ایران
2 استادیار ، پژوهش، مؤسسۀ تحقیقات جنگلها و مراتع کشور، سازمان تحقیقات، آموزش و ترویج کشاورزی، تهران، ایران
3 کارشناس پژوهش، مؤسسۀ تحقیقات جنگلها و مراتع کشور، سازمان تحقیقات، آموزش و ترویج کشاورزی، تهران، ایران
4 مربی پژوهش، بخش تحقیقات منابع طبیعی، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان چهار محال و بختیاری، سازمان تحقیقات، آموزش
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and objectives: Estimating the volume stock of poplar plantations is crucial for understanding their current status and ensuring sustainable management in order to production planning and enhances decision-making for the development of wood farming. Volume tables, as one of these key tools, enable economic planning and optimization of exploitation. For the development of these tables, the use of non-destructive sampling that allow estimating volume without damaging the trees is of great importance. The aim of this research is to prepare a single- and double-entry volume tables for white poplar (Populus alba L.) species in Chaharmahal & Bakhtiari province, so that it is possible to sell poplar wood based on volume and provide more profit to the poplar farmer.
Materials and methods: To conduct this research, first, main poplar stands in Chaharmahal & Bakhtiari province were identified through field operations. Then, in 10 different poplar stands with Populus alba L., a total of 67 trees were selected by using stratified random sampling method, based on diameter classes from 10 to 30 cm. For each selected tree, diameter at breast height (DBH) and total height were measured. Using a Leica D810 laser-based device, from the stem collar of each sample tree, diameters at both ends of each 2-m log along the stem were measured without felling the trees. In the next step, the actual stem volume of each tree was then calculated by summing the volumes of the 2-m logs, obtained from the Smalian’s formula. To evaluate the accuracy of the Leica D810 device in measuring stem diameters at various heights, a set of 13 poplar trees, which were previously scheduled for felling, were used. The diameters of these trees at different stem heights before and after felling were measured using a Leica device and Caliper, respectively, and compared using a paired Student’s t-test. To develop volume tables, data on diameter, height, and stem volume of sample trees were analyzed using nonlinear regression models. For this purpose, seven single-entry models (based on DBH alone) and nine double-entry models (based on both DBH and total height) were fitted for the data of diameter with actual stem volume and diameter and height with actual stem volume of trees, respectively. Then, model performance was evaluated using AIC (Akaike Information Criterion), RMSE (Root Mean Square Error), MAE (Mean Absolute Error), NSE (Nash-Sutcliffe Efficiency), and WI (Willmott Index of Agreement) to select the best model.
Results: The results of the paired t-test showed that no significant difference between the Leica and caliper in diameter measurements, in other words, the two devices performed the same for measuring the diameter. For estimating the volume stock and prepare a single- and double-entry volume tables, among the models, Schumacher-Hall model (RMSE%= 10% & R2= 0.98) performed best for double-entry, while the Berkhout model (RMSE%= 17% & R2= 0.95) showed the highest accuracy for single-entry. Single- entry (one- way) volume table was obtained based on the equation V=0.00003776×D2.969 and double- entry (two- way) volume table was prepared based on the equation V=0.0000276×D2.295×H0.7785.
Conclusion: The regression models developed in this study can be effectively used to estimate the standing volume of white poplar trees, aiding in plantation management and wood volume-based sales. The findings of this study can be valuable baseline information for use in determining the accurate standing and saleable volume of each poplar stand, planning and management decisions regarding harvesting, growth analysis, and sustainable management strategies in the field of wood farming development and related industries development in Chaharmahal & Bakhtiari province.
کلیدواژهها [English]
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