Phenological pattern of leaf-fall phenophase in Quercus robur L. populations of the Belgrade area

Our study of phenological variability in the common oak (Quercus robur L.) was mainly focused on the analysis of the leaf-fall phenophase. The observations were made in two populations in the area of Belgrade (Serbia). We observed 29 trees in each site, during three consecutive years. According to the results of a nonparametric analysis of Mann-Whitney U test we found differences in the leaf fall phenophase (the start, the length and the end) among the populations: statistically significant differences were verified for the start and the length of the leaf fall in two of three observed years, and for the end of leaf fall in one observed year. The differences in the leaf fall within each population among the observed years were verified by the F-test at the significance level of P < 0.05: statistically significant differences were found for the start of leaf fall in “Ada Ciganlija” population, and for the length and the end of leaf fall in both populations. According to the phenological pattern of population 31% of trees in “Ada Ciganlija“ population and 24.1% of trees in “Bojčin forest“ population did not change its phenological group in relation to the start of the leaf fall (“early“, “average“ and “late“) during three years of observation. Since the phenological traits are under significant influence of both environmental and genetic factors, it is very important to evaluate those factors according to tree differentiation to phenological groups for pedunculate oak selection. An overview of the pattern of leaf fall phenology and the response to the changing climatic factors will help in understanding the leaf fall phenology at the level of an individual and at the level of species