Investigation on vertical structure and spatial associations of Fagus orientalis lipsky using O-ring function in Kheyrud forest, Nowshahr

This study aims at analyzing spatial pattern and associations of Fagus oriantalis Lipsky in different vertical classes in intact beech forests. Data collection was done in 25 ha plot in Gorazbon district of Educational and Experimental Forests of University of Tehran. Species and DBH of all trees with DBH > 7.5 cm were recorded. The location of each tree was determined using azimuth and distance method in order to map the tree positions. Height of trees was calculated using diameter – height model developed for Gorazbon district. Trees were then divided in 4 Height classes: 25 m (U). Univariate O-ring statistic was used to analyze the spatial patterns of Fagus orientalis at different tree height classes, and the bivariate O-ring statistic was used to analyze interspecies spatial associations among these height classes. Programita software was used for all analysis. Results showed spatial pattern of Fagus orientalis in height class (S) was clustered. In height class (L) spatial pattern was clustered up to distance of 21 m and then changed to random pattern. In height class (M) spatial pattern was aggregated up to distance 8 meter and then changed to random pattern and in height class (U) Fagus orientalis showed random spatial pattern in all distances. Bivariate O-ring analysis showed positive correlation between trees at height class (S) and other height classes up to 30-40 m. Present study showed application of O-ring statistic in vertical structure analysis of forest ecosystems.