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Three k-tree distance and fixed-sized 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 non-timber-oriented forest but important for protection purposes. The main objective was to investigate the statistical performance of k-tree distance and fixed-sized plot designs in the estimation of tree density. In addition, the cost (time required) of data collection using both k-tree distance and fixed-sized plot designs was estimated. Monte-Carlo sampling simulation was used in order to compare the different strategies. The bias of the k-tree 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 cost-efficiency, Moore’s estimator was the best and Prodan’s estimator was superior to Kleinn and Vilcko’s estimator. Cost-efficiency of k-tree distance design is related to three factors: sample 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 four-study sites. Thus, it can be concluded that Moore’s estimator can have a better performance in forests with different tree distribution.

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Spatially explicit estimates of aboveground biomass over large area are necessary for natural resources managers. This study examined aboveground biomass and carbon stock of the wild pistachio (Pistacia atlantica) based on individual tree crown detection and allometric development in the arid woodlands using high-resolution satellite images of GeoEye-1 in a reserved forest area of Wild Pistachio trees in the South Khorasan Province, East of Iran. Biomass of sampled trees was determined using field sampling and experimental tests. In addition, the biomass of stems was determined using volume and density. The allometric biomass and carbon stock equations of Wild Pistachio trees were developed based on crown area, diameter at breast height (1.3 m), and height of trees. The trees crowns were detected and delineated on the GeoEye-1 images, using local maxima filters, and region growing segmentation algorithms, respectively. In addition, a morphological watershed transformation method was applied to split the connected and overlapped tree crowns. Performing algorithms was assessed using the measured field crown of sample trees by precision, recall, and overall accuracy indices. The biomass and carbon stock of trees of the study area were estimated using delineated crown area and the developed allometric equations. The results showed that the equation that used crown area could explain more than 80% of the remarked variation in biomass and carbon stock. In addition, the crown detection method results showed that overall detection rate and the quality of crown boundaries were acceptable. In conclusion, the study confirmed that combining the allometric equations with crown information from high-resolution images could contribute to the explicit mapping of biomass and carbon stock of wild pistachio trees in the arid woodlands.