Comparison of developmental stages in Beech-Hornbeam stands using non-spatial indices of stand structure

Forest stand structural development occurs over time and is commonly studied based on initial, optimal and decay developmental stages. The purpose of this study was to evaluate the capability of non-spatial indices for differentiating among developmental stages of beech-hornbeam stand in Haji-Kola- Tirankoli forest of Sari in Mazandaran province. Three sample plots were selected in each developmental stage (totally 9 sample plots). The characteristics of trees with a diameter > 7.5 cm were measured in each plot, including species, diameter at breast height and total height. The results of analysis of variance revealed significant differences amongst the developmental stages for basal area, volume, density, density of large trees, standard deviation of diameter and height, diameter and height of overstory, leaf area index, relative light intensity, species richness of over story, basal area of large to mature trees, modified Frelich-Lorimer index. Nevertheless, other attributes including DBH, density of trees > 100 cm, deadwood diameter, and number of dead wood, Gini coefficient, Doliucort index, Structural Complexity index, and Cox index did not differentiate among the developmental stages. The structure triangle and the Frelich-Lorimer index were shown to properly determine the stage of stand development.