Efficiency Evaluating of Distance Indices in Estimating Tree’s Spatial Distribution Pattern in Arasbaran Forest

The spatial distribution of trees is one of the most important structural features of forest stands, which considered as an indicator for sustainable development stage of stand, biodiversity, ecological stability, competition processes and the overall process of forest ecosystems. Therefore, every change in the spatial distribution of trees plays an important role in these functions. The main purpose of this study was to investigate the efficiency evaluating of the Distance to neighbor, the Eberhardt, Hopkins and Johnson-Zimmer indices in estimating the spatial distribution of natural forest stands in Arasbaran forest. The diameter and height of reference trees and three nearest neighbor, distance and the angle between the reference and neighbors trees measured in the 60 sampling points. Results showed that Distance to neighbor index indicated that the mean of measured distances between trees was 4.2 ± 0.08 meters and 4-6 meters distance had the highest frequency among the measures. The value of the Eberhardt, Hopkins and Johnson-Zimmer indices were 1.08, 0.63 and 1.29 respectively that showed uniform distribution pattern in studied stand. Statistical analysis confirmed the spatial distribution patterns predicted at 95% level by these indicators. Protective activities in the Arasbaran forest make it largely reliable to represent the actual pattern of species distribution. Therefore, it is possible to prepare a map of the distribution pattern, more appropriate and accurate results of the species stands structure and the possibility of completing the ecological database of the region and provide valuable data to assist the regional management plans.