Zagros forests are one of the most important forest ecosystems in Iran. Even though forest service in the organization of forest and rangelands considers Zagros forest as protected forests, local population use these recourses. The purpose of this research was to study and compare diameter increment of Quercus infectoria in pollarded and less-disturbed stands in Northern Zagros. Two forms of stands were selected as follows: less – disturbed stand and pollarded stand with same situation regarding physiographic characteristics. Eighteen coppice trees were randomely selected. Pairs of increment cores were extracted from each tree with increment borer at 50 cm of height. Normality test with Kolmogrov – Smirnov test indicated the data are normal. The means of diameter increment of Quercus infectoria were 2.14 mm and 1.23 mm in polarded and less-disturbed stands, respectively. The mean of diameter increment percent of Quercus infectoria was 13.77% and 6.78% in the studied stands. The comparison of diameter increment of Quercus infectoria in both pollarded and less – disturbed stands was carried out with independent samples t-test. Based on the results, mean diameter increment of Quercus infectoria in diameter classes in pollarded stand was more than the others and the difference of diameter increment in two stands was statistically significant (P< 0.01).
