Estimation of acorn production of gall oak (Quercus infectoria Olivier) in Baneh forests using Koenig visual method

Study of sexual regeneration of oak species in Zagros forests is very important considering to sever degradation of these forests and decreasing of seed origin oaks. Acorn production is the first step in the sexual regeneration cycle which has an important impact on forest sustainability. Regarding to difficult process of acorn counting, there is unfortunately, no adequate information about acorn production of Zagros native oaks. Therefore, this research was conducted using Koenig visual method for the first time in the western oak forests of Iran. The study was carried out in a section of northern Zagros forests near to Halou village located in 40 km west of Baneh, Kurdistan province. At first, 90 gall oaks (Quercus infectoria Olivier) were selected using stratified random sampling method. For each tree, all of acorns were counted with two 1) crown counting and 2) Koenig visual estimation. Result showed that the mean, minimum and maximum of acorns number/m2 crown area were 10.3, 0.1 and 278.9, respectively. These values were 158.8, 3 and 2917 for the acorns number per tree, which indicates that total acorn production was poor in the study area. Finally, the best regression model was calculated to estimate total number of acorns using Koenig visual estimation method. Obtained model showed a high correlation which is applicable for easy estimation of acorn number of other gall oaks in the studied forest in the next years.