University of Guilan Forest Sustainable Development 1 2 2014 08 23 Effects of three different silvicultural systems on diameter distribution in Shafaroud forest stands of Iran Effects of three different silvicultural systems on diameter distribution in Shafaroud forest stands of Iran 119 136 69 FA Behzad Bakhshandeh Navrood Ph.D. Student, Faculty of Agriculture, University of Lurestan, Iran Javad Soosani Assistant Professor, Faculty of Agriculture, University of Lurestan, Iran Sheyda Khosravi Ph.D. Student, Faculty of Agriculture, University of Lurestan, Iran Hesamodin Barzkoohi M.Sc. graduated of Forestry, Islamic Azad University of Lahijan, Iran Mehrzad Naseri Khalkhali M.Sc. graduated of Forestry, Islamic Azad University, Science and Research Branch, Tehran, Iran Journal Article 2013 10 11 The implementation of different silvicultural systems can be effective on different characteristics of forest stands, such as stand structure and diameter distribution of trees. This study was carried out in Shafaroud forests of Gilan province of northern Iran. The objectives of this research were 1) to evaluate the suitability of different probability distribution functions, including Weibull, Beta, Gamma, Johnson, Lognormal, normal and exponential, for modeling tree distribution in diameter classes and, 2) to compare changes of diameter distributions after ten years of implementation of three different silvicultural systems. The tested systems were single-tree selection, shelterwood and strip cutting. Also, there was an untreated stand. The results of Chi-square and Kolmogorov-Smirnov tests showed that the Johnson, gamma and Lognormal models were often more flexible to fit various diameter distributions, while in any case, the beta and exponential probability distribution did not provide satisfactory descriptions of the experimental data. Other results indicated the change in the diameter distribution due to the implementation of the strip management system, a decade after timber harvest. This may mean that strip cutting can disturb the stand structure in the studied forests. Also, there were no significant changes in the diameter distributions after implementation of the other silvicultural systems. The implementation of different silvicultural systems can be effective on different characteristics of forest stands, such as stand structure and diameter distribution of trees. This study was carried out in Shafaroud forests of Gilan province of northern Iran. The objectives of this research were 1) to evaluate the suitability of different probability distribution functions, including Weibull, Beta, Gamma, Johnson, Lognormal, normal and exponential, for modeling tree distribution in diameter classes and, 2) to compare changes of diameter distributions after ten years of implementation of three different silvicultural systems. The tested systems were single-tree selection, shelterwood and strip cutting. Also, there was an untreated stand. The results of Chi-square and Kolmogorov-Smirnov tests showed that the Johnson, gamma and Lognormal models were often more flexible to fit various diameter distributions, while in any case, the beta and exponential probability distribution did not provide satisfactory descriptions of the experimental data. Other results indicated the change in the diameter distribution due to the implementation of the strip management system, a decade after timber harvest. This may mean that strip cutting can disturb the stand structure in the studied forests. Also, there were no significant changes in the diameter distributions after implementation of the other silvicultural systems. https://fsdj.guilan.ac.ir/article_69_1709a5057c82ea7a64168614bd360736.pdf