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Papers by Mehrdad Mirzaei

Research paper thumbnail of Diameter Distribution Modeling of Quercus Persica Using Probability Distribution Functions in Open Forests (Case Study: Dalab of Ilam Province)

The diameter at breast height of tree is one of the important characteristics in forest measureme... more The diameter at breast height of tree is one of the important characteristics in forest measurements. Diameter structure of forest stands can be determined based on diameter distribution. The distribution of diameter classes is the most important structural characteristics of forest stands. The aim of this study was to evaluate the DBH probability distribution of Quercus persica trees in Dalab open forests of Ilam province. For this purpose, 37 transects with fixed length (50 m) were measured and trees distribution in diameter classes for 209 trees were fitted. The probability distribution functions including: Beta, Gamma, Normal and Log-normal were fitted to the DBH distribution of oak trees. The maximum likelihood estimator was used to evaluate the distribution functions parameters. Expected probability and probability derived from functions were compared using Kolmogorov-Smirnov and Chi-square tests. Results of fitting tests and P-P plots showed that Beta and Normal distributions were the best probability for diameter distribution modeling in Dalab open forests of Ilam province.

Research paper thumbnail of Defining the most appropriate transect method for estimation of Basal area: case study in Dalab forests, Ilam Province

تحقیقات جنگل و صنوبر ایران, 2014

Forest management and planning require a proper level of quantitative and qualitative information... more Forest management and planning require a proper level of quantitative and qualitative information on forest stands. Such data is usually collected by means of different sampling methods e.g. transect method. This study aims at exploring the most appropriate sampling method for estimating basal area incorporating their on precision and cost in a case study of Dalab forests of Ilam province. To this aim, a representative area encompassing 37.2 hectares of forests was selected and surveyed by a 100% inventory. Three sampling methods (transect based on probability theory, transect with fixed 50 m length and transect with fixed number of 5 trees) were applied. Based on a regular random sampling pattern, 37 samples were selected for each sampling method in a 100 × 100m grid. The results showed significant difference between the measured basal area and those estimated by any of the three sampling methods. The E%2×T criteria was additionally applied for a better evaluation of the applied sa...

Research paper thumbnail of Diversity of Tree Species in Protected Forests of Ardal’s Chartagh

Research paper thumbnail of Comparison of Frequencies in Order to Estimate of Tree Species Diversity in Caspian Forests of Iran

Journal of forest and environmental science, 2019

Research paper thumbnail of Modeling of Frequency Distribution of Tree’s Height in Uneven-Aged Stands in Dalab of Ilam

The aim of this research, was to model the height frequency distribution of Quercus persica in Da... more The aim of this research, was to model the height frequency distribution of Quercus persica in Dalab forests of Ilam. In order to investigate the height frequency distribution of trees in the natural stands, 37 transect with fixed length (50m) selected and data were measure based on systematic random patterns with 100m×100m dimensions of network inventory. Finally, height of 209 trees of oak were measured and analyzed. Beta, Exponential, Gamma, Normal, Log- normal and Weibull probability distribution functions were fitted to the height distribution of oak trees. Characteristics of distribution function using the maximum likelihood estimation method was estimated. Empirical probability distribution and theoretical probability distribution was compared using Kolmogorov Smirnov and Chi square tests. The results of the Kolmogorov Smirnov test showed that Beta, Normal, Weibull, Gamma and Log-normal distributions were fitted to data better respectively; but the Chi square test showed that Beta and Log-normal distributions had a good capability in explaining the trees height distribution. We concluded that Beta and Log-normal probability distributions can be used for those who want to simulate changes of forests.

Research paper thumbnail of The Application of Statistical Distributions in Oak Forests

The prediction of the distribution of quantitative variables in a forest stand is of great intere... more The prediction of the distribution of quantitative variables in a forest stand is of great interest to forest managers, for the evaluation of forest resources and scheduling of future silvicultural treatments. The aim of this research was to model the distribution of quantitative variables for Quercus brantii var. persica in protected, degraded and natural forests of Iran. Gamma, beta, normal, lognormal, exponential and Weibull probability distribution functions were fitted to the height, DBH and canopy distribution of trees. Variables of distribution functions were estimated using the maximum likelihood estimation method. Actual probability and probability which derived from functions was compared using Kolmogorov-Smirnov and Anderson-Darling tests.

Research paper thumbnail of Assessing Impact of Physiographic Factors on Spatial Distribution Patterns of Oak Trees in Iran

Forest Research: Open Access, 2016

Research paper thumbnail of Comparison of fixed area and distance sampling methods in open forests: case study of Zagros Forest, Iran

Journal of Forestry Research, 2016

Research paper thumbnail of Easy and Quick Survey Method to Estimate Quantitative Characteristics in the Thin Forests

Journal of Forest and Environmental Science, 2015

Research paper thumbnail of Modeling frequency distributions of tree height, diameter and crown area by six probability functions for open forests of Quercus persica in Iran

Journal of Forestry Research, 2015

Research paper thumbnail of Effects of inventory grids on estimation of tree species diversity in semi-arid forests of Iran

Folia Oecologica

Species diversity is one of the most important indices used to evaluate the sustainability of for... more Species diversity is one of the most important indices used to evaluate the sustainability of forest communities. The sampling method and the number of plots are factors affecting the estimation of plant biodiversity. In the present study, effects of different inventory grids on estimation of tree species diversity were compared in semi-arid forests of Iran. There were selected 50 hectares of these forests representing the regional forests. Sampling procedures were carried out on circular plots (1,000m2) within inventory grids, with dimensions of 50 × 50 m (200 plots), 100 × 50 m (100 plots), 100 × 100 m (50 plots), 200 × 50 m (50 plots), 200 × 100 m (25 plots), and 250 × 200 m (10 plots). For each plot, the type of the species and the number of trees were recorded. Simpson (1-D), Hill (N2), Shannon-Wiener (H’), Mc Arthur (N1), Smith-Wilson (Evar) and Margalef (R1) indices were used to estimate the tree species diversity. The inventory grid was evaluated based on the precision and c...

Research paper thumbnail of Diameter Distribution Modeling of Quercus Persica Using Probability Distribution Functions in Open Forests (Case Study: Dalab of Ilam Province)

The diameter at breast height of tree is one of the important characteristics in forest measureme... more The diameter at breast height of tree is one of the important characteristics in forest measurements. Diameter structure of forest stands can be determined based on diameter distribution. The distribution of diameter classes is the most important structural characteristics of forest stands. The aim of this study was to evaluate the DBH probability distribution of Quercus persica trees in Dalab open forests of Ilam province. For this purpose, 37 transects with fixed length (50 m) were measured and trees distribution in diameter classes for 209 trees were fitted. The probability distribution functions including: Beta, Gamma, Normal and Log-normal were fitted to the DBH distribution of oak trees. The maximum likelihood estimator was used to evaluate the distribution functions parameters. Expected probability and probability derived from functions were compared using Kolmogorov-Smirnov and Chi-square tests. Results of fitting tests and P-P plots showed that Beta and Normal distributions were the best probability for diameter distribution modeling in Dalab open forests of Ilam province.

Research paper thumbnail of Defining the most appropriate transect method for estimation of Basal area: case study in Dalab forests, Ilam Province

تحقیقات جنگل و صنوبر ایران, 2014

Forest management and planning require a proper level of quantitative and qualitative information... more Forest management and planning require a proper level of quantitative and qualitative information on forest stands. Such data is usually collected by means of different sampling methods e.g. transect method. This study aims at exploring the most appropriate sampling method for estimating basal area incorporating their on precision and cost in a case study of Dalab forests of Ilam province. To this aim, a representative area encompassing 37.2 hectares of forests was selected and surveyed by a 100% inventory. Three sampling methods (transect based on probability theory, transect with fixed 50 m length and transect with fixed number of 5 trees) were applied. Based on a regular random sampling pattern, 37 samples were selected for each sampling method in a 100 × 100m grid. The results showed significant difference between the measured basal area and those estimated by any of the three sampling methods. The E%2×T criteria was additionally applied for a better evaluation of the applied sa...

Research paper thumbnail of Diversity of Tree Species in Protected Forests of Ardal’s Chartagh

Research paper thumbnail of Comparison of Frequencies in Order to Estimate of Tree Species Diversity in Caspian Forests of Iran

Journal of forest and environmental science, 2019

Research paper thumbnail of Modeling of Frequency Distribution of Tree’s Height in Uneven-Aged Stands in Dalab of Ilam

The aim of this research, was to model the height frequency distribution of Quercus persica in Da... more The aim of this research, was to model the height frequency distribution of Quercus persica in Dalab forests of Ilam. In order to investigate the height frequency distribution of trees in the natural stands, 37 transect with fixed length (50m) selected and data were measure based on systematic random patterns with 100m×100m dimensions of network inventory. Finally, height of 209 trees of oak were measured and analyzed. Beta, Exponential, Gamma, Normal, Log- normal and Weibull probability distribution functions were fitted to the height distribution of oak trees. Characteristics of distribution function using the maximum likelihood estimation method was estimated. Empirical probability distribution and theoretical probability distribution was compared using Kolmogorov Smirnov and Chi square tests. The results of the Kolmogorov Smirnov test showed that Beta, Normal, Weibull, Gamma and Log-normal distributions were fitted to data better respectively; but the Chi square test showed that Beta and Log-normal distributions had a good capability in explaining the trees height distribution. We concluded that Beta and Log-normal probability distributions can be used for those who want to simulate changes of forests.

Research paper thumbnail of The Application of Statistical Distributions in Oak Forests

The prediction of the distribution of quantitative variables in a forest stand is of great intere... more The prediction of the distribution of quantitative variables in a forest stand is of great interest to forest managers, for the evaluation of forest resources and scheduling of future silvicultural treatments. The aim of this research was to model the distribution of quantitative variables for Quercus brantii var. persica in protected, degraded and natural forests of Iran. Gamma, beta, normal, lognormal, exponential and Weibull probability distribution functions were fitted to the height, DBH and canopy distribution of trees. Variables of distribution functions were estimated using the maximum likelihood estimation method. Actual probability and probability which derived from functions was compared using Kolmogorov-Smirnov and Anderson-Darling tests.

Research paper thumbnail of Assessing Impact of Physiographic Factors on Spatial Distribution Patterns of Oak Trees in Iran

Forest Research: Open Access, 2016

Research paper thumbnail of Comparison of fixed area and distance sampling methods in open forests: case study of Zagros Forest, Iran

Journal of Forestry Research, 2016

Research paper thumbnail of Easy and Quick Survey Method to Estimate Quantitative Characteristics in the Thin Forests

Journal of Forest and Environmental Science, 2015

Research paper thumbnail of Modeling frequency distributions of tree height, diameter and crown area by six probability functions for open forests of Quercus persica in Iran

Journal of Forestry Research, 2015

Research paper thumbnail of Effects of inventory grids on estimation of tree species diversity in semi-arid forests of Iran

Folia Oecologica

Species diversity is one of the most important indices used to evaluate the sustainability of for... more Species diversity is one of the most important indices used to evaluate the sustainability of forest communities. The sampling method and the number of plots are factors affecting the estimation of plant biodiversity. In the present study, effects of different inventory grids on estimation of tree species diversity were compared in semi-arid forests of Iran. There were selected 50 hectares of these forests representing the regional forests. Sampling procedures were carried out on circular plots (1,000m2) within inventory grids, with dimensions of 50 × 50 m (200 plots), 100 × 50 m (100 plots), 100 × 100 m (50 plots), 200 × 50 m (50 plots), 200 × 100 m (25 plots), and 250 × 200 m (10 plots). For each plot, the type of the species and the number of trees were recorded. Simpson (1-D), Hill (N2), Shannon-Wiener (H’), Mc Arthur (N1), Smith-Wilson (Evar) and Margalef (R1) indices were used to estimate the tree species diversity. The inventory grid was evaluated based on the precision and c...