Quantifying structure of intact beech (Fagus orientalis Lipsky) stands at different development stages (Case study: Kelardasht area, Mazandaran)

Forest structure is influenced by natural processes and human interventions. For proper forest management, some tools are required to study changes made at forest structure. In this study, to investigate changes made at structure of intact and natural forest of Kelardast area of Caspian Forests of Iran, three one-hectare area plots, representative of initial, optimal and decay stages of forest development, were used. After measuring distance and azimuth of each tree to the southwest corner of each sampling plot and recording some parameters such as species, diameter at breast height (dbh) and total height, three characteristics, including geographical location (Clark & Evans and uniform angle indices), mixture (Mingling index) and tree dimensions (dbh and total height differentiation indices) were studied, using a set of indices, based on nearest neighbor criteria. Results of this study showed that greatest density of trees was found at the initial stage and according to the Clark & Evans index, distribution pattern of the trees at initial and decay stages in one hand and at optimal stage at second hand was clumped and random, respectively. Furthermore, result of the uniform angle index showed that the trees arrangement within the structural groups at the three development stages was at random form. Results of Mingling index showed that mixture at initial stage was at lowest rate, compared to the other development stages. Moreover, result of dbh and total height differentiation indices showed that there were moderate-obvious and low-moderate variations for the trees at the three development stages, respectively. Regarding the intactness of the studied stands, results of these indices might be applied as a basis for similar forests and determination variation rates caused by natural processes and human interventions.