Individual and annual variation in acorn production of Brant's oak (Quercus brantii Lindl.) in Darbadam Forest of Kermanshah Province

Production of tree seeds is associated with considerable variations within individuals and among years. In this study, individual and annual variation in acorn production of Brant`s oak (Quercus brantii Lindl.) was studied in Darbadam Forest, Kermanshah province during 2009-2011. A number of 40 sample trees were selected by stratified random sampling method, followed by measurement of their quantitative variables. Prior to acorn fall in early September, the number of acorns per tree was determined by crown count method. In addition, acorn density (acorn number/m2 crown area) was calculated to compare the potential of acorn production. The result showed great variability within individuals and among years. Some sample trees had no acorns; meanwhile acorn density was more than 40 in some trees. The weakest and the best acorn production were observed in 2009 (mean acorn density= 1.6) and 2010 (mean acorn density=10.7), respectively. The last year of study (2011) showed a moderate condition. Significant differences (P<0.05) were solely observed between acorn density of different diameter classes in 2010. Furthermore, the differences in acorn density amongst trees in similar diameter classes among years were only significant (P<0.01) for medium diameter classes. In conclusion, the results confirmed the effect of inherent tree species capability and the seeding year on acorn production of Brant`s oaks.