Volume 13, Issue 2 (10-2025)
Ecol Iran For 2025, 13(2): 130-142 |
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Mahdavi A, Yaghobi R, Omidi M, Naji H R. (2025). Evaluation of Allometric Relationships to Estimate Leaf Biomass, Carbon Sequestration, and Leaf Area Index of Acer monspessulanum subsp. Cinerascens. Ecol Iran For. 13(2), 130-142. doi:10.61882/ifej.2025.549
URL: http://ifej.sanru.ac.ir/article-1-549-en.html
URL: http://ifej.sanru.ac.ir/article-1-549-en.html
1- Department of Forest Sciences, Faculty of Agriculture, Ilam University, Ilam, Iran
2- Department of Statistics and Mathematics, Faculty of Basic Sciences, Ilam University, Ilam, Iran
2- Department of Statistics and Mathematics, Faculty of Basic Sciences, Ilam University, Ilam, Iran
Abstract: (814 Views)
Extended Abstract
Background: The biomass estimation of different tree organs plays a key role in sustainable management and the estimation of forest carbon stocks. Relationships that relate the characteristics of tree size (such as the diameter and height) to its biomass are called allometric relationships. This study aimed to determine allometric equations for estimating biomass, carbon sequestration, and leaf area index (LAI) of Acer monspessulanum subsp. cinerascens species in the protected areas of Manshet and Ghalarnang forests in Ilam Province.
Methods: For this purpose, initially, the different sites of Acer monspessulanum in the study area were determined by a forest tour. Afterward, quantitative factors (such as large and small crown diameter, tree height, crown length, and collar diameter) were measured in 60 randomly selected Acer monspessulanum trees. To estimate the leaf biomass, a quarter to an eighth of the leaves of the tree crown were collected by the direct method of picking, according to the size and smallness of the tree crowns of the A. monspessulanum sample trees. The dry weight was measured in oven-dried leaves. The numbers obtained from a quarter or an eighth of the crown surface by multiplying by 4 or 8 were determined as the leaf dry weight of the entire tree crown. The percentage of organic carbon (0.47%) was obtained by burning a sufficient amount of dried leaves in an electric furnace. The LAI of A. monspessulanum subsp. trees was calculated using the specific surface area of the leaves through the weighing method. The average tree method was used to generalize the results obtained from the sample trees to the whole forest. The Kolmogorov-Smirnov test was used for the normality of the data. Linear and non-linear (logarithmic and power) regressions were used to examine the allometric relationships between biomass, carbon sequestration, and LAI as the dependent variables with the measured independent quantitative variables of the tree (such as average crown diameter and tree height). Based on the criteria of the coefficient of determination and the adjusted coefficient of determination, the best model was selected among the three investigated models. The decision to confirm or reject the assumption of no effect of the independent variable on the dependent variable was made based on the p-value.
Results: The results of the Kolmogorov-Smirnov test showed a normal distribution of the data. The average leaf biomass, average carbon storage in leaves, and average carbon dioxide absorption from the atmosphere by A. monspessulanum subsp. Cinerascens trees were estimated at 200.30, 94.16, and 345.68 kg/ha, respectively, in the protected areas of Manshet and Ghalarnang. The results of LAI estimation in the study area showed that the average LAI for
A. monspessulanum subsp. cinerascens species was 1.52 per tree and 0.119 per ha, respectively. The results of the analysis of different models showed that the collar diameter as the independent variable did not affect LAI as the dependent variable in all the investigated regression models, with a p-value more than 0.05 for all three regression models, which shows no significant effect of the collar diameter on LAI. Meanwhile, the average crown diameter as the independent variable in all three investigated models showed a significant effect on the LAI as the dependent variable based on the p-values. Besides, the power model showed the highest coefficient of determination (0.407) and adjusted coefficient of determination (0.397) for the average crown diameter as the independent variable. The results revealed the significant effects of independent variables (collar diameter, average crown diameter, and average crown area) on leaf dry biomass (the dependent variable) in A. monspessulanum subsp. cinerascens trees in linear, logarithmic, and power regression models based on the p-value of all three independent variables in all three investigated
models. Among the other models, however, the power model had the highest coefficient of determination (0.433) and adjusted coefficient of determination (0.423) for the collar diameter as the independent variable. Therefore, the power model was chosen as the best model for the collar diameter (independent variable) and leaf dry biomass (the dependent variable). In addition, the results of the analysis of different models showed that the tree collar diameter (independent variable) could affect leaf carbon sequestration (the dependent variable) in all regression models, with a p-value < 0.05 for all three regression models, showing a significant effect of the tree collar diameter variable on leaf carbon sequestration (the dependent variable). Among the investigated models, the power model for the tree collar diameter (independent variable) has the highest coefficient of determination (0.434) and adjusted coefficient of determination and (0.424). Therefore, this model was chosen as the best model for the tree collar diameter and leaf carbon sequestration as the independent and dependent variables, respectively. Therefore, the examination of allometric relationships using regression equations showed that the power model had the best coefficient of determination and adjusted coefficient of determination for predicting dependent variables based on the mentioned independent variables. Background: The biomass estimation of different tree organs plays a key role in sustainable management and the estimation of forest carbon stocks. Relationships that relate the characteristics of tree size (such as the diameter and height) to its biomass are called allometric relationships. This study aimed to determine allometric equations for estimating biomass, carbon sequestration, and leaf area index (LAI) of Acer monspessulanum subsp. cinerascens species in the protected areas of Manshet and Ghalarnang forests in Ilam Province.
Methods: For this purpose, initially, the different sites of Acer monspessulanum in the study area were determined by a forest tour. Afterward, quantitative factors (such as large and small crown diameter, tree height, crown length, and collar diameter) were measured in 60 randomly selected Acer monspessulanum trees. To estimate the leaf biomass, a quarter to an eighth of the leaves of the tree crown were collected by the direct method of picking, according to the size and smallness of the tree crowns of the A. monspessulanum sample trees. The dry weight was measured in oven-dried leaves. The numbers obtained from a quarter or an eighth of the crown surface by multiplying by 4 or 8 were determined as the leaf dry weight of the entire tree crown. The percentage of organic carbon (0.47%) was obtained by burning a sufficient amount of dried leaves in an electric furnace. The LAI of A. monspessulanum subsp. trees was calculated using the specific surface area of the leaves through the weighing method. The average tree method was used to generalize the results obtained from the sample trees to the whole forest. The Kolmogorov-Smirnov test was used for the normality of the data. Linear and non-linear (logarithmic and power) regressions were used to examine the allometric relationships between biomass, carbon sequestration, and LAI as the dependent variables with the measured independent quantitative variables of the tree (such as average crown diameter and tree height). Based on the criteria of the coefficient of determination and the adjusted coefficient of determination, the best model was selected among the three investigated models. The decision to confirm or reject the assumption of no effect of the independent variable on the dependent variable was made based on the p-value.
Results: The results of the Kolmogorov-Smirnov test showed a normal distribution of the data. The average leaf biomass, average carbon storage in leaves, and average carbon dioxide absorption from the atmosphere by A. monspessulanum subsp. Cinerascens trees were estimated at 200.30, 94.16, and 345.68 kg/ha, respectively, in the protected areas of Manshet and Ghalarnang. The results of LAI estimation in the study area showed that the average LAI for
A. monspessulanum subsp. cinerascens species was 1.52 per tree and 0.119 per ha, respectively. The results of the analysis of different models showed that the collar diameter as the independent variable did not affect LAI as the dependent variable in all the investigated regression models, with a p-value more than 0.05 for all three regression models, which shows no significant effect of the collar diameter on LAI. Meanwhile, the average crown diameter as the independent variable in all three investigated models showed a significant effect on the LAI as the dependent variable based on the p-values. Besides, the power model showed the highest coefficient of determination (0.407) and adjusted coefficient of determination (0.397) for the average crown diameter as the independent variable. The results revealed the significant effects of independent variables (collar diameter, average crown diameter, and average crown area) on leaf dry biomass (the dependent variable) in A. monspessulanum subsp. cinerascens trees in linear, logarithmic, and power regression models based on the p-value of all three independent variables in all three investigated
Conclusion: The results of this study demonstrate the ability to measure biomass, carbon sequestration, and LAI of A. monspessulanum subsp. cinerascens trees using allometric equations.
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