Impacts of oleo- gum resin extraction periodicity on biometric variables of wild pistachio

In order to consider oleo- gum resin extractionperiodicity on biometric variables of wild pistachio (Pistacia atlantica subsp. kurdica), three different forest areas in Kurdistan province, west of Iran, were selected based on difference extraction periodicities (regular, irregular and without periodicity). Then homogenous unit maps in GIS environment produced, and one unit with identical characteristic from any three different areas were selected. Sampling in the selected units was implemented on 100 randomized pistachio tress with diameter at breast height (DBH) more than 25 cm. On each tree, DBH, total height, crown diameter and number of fruit bunches were recorded. Then the measured trees were classified to three different diameter classes as: 25- 35 cm, 35-45 cm and more than 45 cm diameter at breast height. Comparison between averages of the interested variables was done using ANOVA and Duncan tests. Results showed that except to the average of number of clusters, the averages of other interested variables, at least in one diameter classes, were significantly higher in the area with regular extraction periodicity compare to the area with irregular extraction periodicity. Finally, we concluded that oleo- gum resin extraction without regular periodicity had a negative impact on biometric variables of wild pistachio, therefore, we propose to consider the periodicity in the future extraction