The resin of wild pistachio trees (Pistacia atlantica Desf.) plays a great role in the social and economic aspects of the Zagros forest region due to supplying livelihoods for forest dwellers. The objective of this study is to assess the resin exploitation impact on biometric indices of wild pistachio. Two forest stands including, a less disturbed stand (i.e., without resin exploitation) with an area of 47.5 ha and a utilized stand (i.e., undergoing resin exploitation) with an area of 43 ha, with similar physiographic conditions were selected in the Kurdistan province, western Iran. The locations and boundaries of the selected stands were separately determined using a GPS device. A full inventory was performed such that the tree species and diameter at breast height (dbh) for all trees (diameter at breast hight≥5 cm) were recorded. Moreover, some quantitative characteristics (collar diameter, total height, trunk height, and crown diameter) were also measured in wild pistachio trees. Results showed that the average of biometric indices (diameter at breast height, collar diameter, crown diameter, total height and crown height) in the less disturbed stand (40.4 cm, 77.1 cm, 7.5 m, 6.8 m and 4.0 m, respectively) and the utilized stand (26.4 cm, 53.9 cm, 5.2 m, 4.9 m and 1.8 m, respectively) were significantly different. There was a significant difference in the average of trunk height in diameter class of 25-95 cm between the less disturbed (2.9 m) and utilized (3.1 m) stands.
