Evaluation of K-tree Distance and Fixed-Sized Plot Sampling in Zagros Forests of Western Iran

Three ktree distance and fixedsized plot designs were used for estimating tree density in sparse Oak forests. These forests cover the main part of the Zagros mountain area in western Iran. They are nontimberoriented forest but important for protection purposes. The main objective was to investigate the statistical performance of ktree distance and fixedsized plot designs in the estimation of tree density. In addition, the cost (time required) of data collection using both ktree distance and fixedsized plot designs was estimated. MonteCarlo sling simulation was used in order to compare the different strategies. The bias of the ktree distance designs estimators decreased with increasing the value of k. The Moore’s estimator produced the smallest bias, followed by Kleinn and Vilcko andthen Prodan. In terms of costefficiency, Moore’s estimator was the best and Prodan’s estimator was superior to Kleinn and Vilcko’s estimator. Costefficiency of ktree distance design is related to three factors: sle size, the value of k, and spatial distribution of trees in a forest stand. Moore’s estimator had the best statistical performance in terms of bias, in all fourstudy sites. Thus, it can be concluded that Moore’s estimator can have a better performance in forests with different tree distribution.