Length of vegetation period as parameter of common oak (Quercus robur L.) phenological variability

Paper presents results for length of vegetation period as factor in common oak’s (Quercus robur L.) phenological variability. Trees in two common oaks populations on two locations in area of Belgrade were researched. Average length of vegetation period on site Ada Ciganlija is 166 days, while in location Boj inska uma is 179 days. Regarding that populations are in similar environmental and habitual conditions, differences in results should be treated as consequence of common oaks intra-specific variability and genetic structure of population. Significant differences in three consecutive years of observation are confirmed.