FEATURES OF REPRODUCTIVE PROCESSES IN CLONED PLANTATIONS OF COMMON OAK WITH DIFFERENT THINNING REGIMES IN THE CONDITIONS OF VINNYTSIA REGION

The article presents the results of a study on the phenological structure and seed productivity of Quercus robur L. trees on clonal seed orchards with different thinning intensities, located within the Turbiv forestry unit of the Vinnytsia Forest Research Station. The research was conducted in 2025 on three experimental plots representing varying levels of stand density (unthinned, moderate thinning, and intensive thinning). Five phenological forms of trees were identified: early, early-intermediate, intermediate, late-intermediate, and late. On the unthinned plot, late (34.7%) and late-intermediate (32.3%) forms predominated, while early and early-intermediate trees accounted for only 2.4-4.8%. Increasing thinning intensity led to a more balanced distribution of phenological forms and an increase in the proportion of intermediate types. An analysis of reproductive activity revealed a clear dependence on thinning intensity. The mean fruiting score was 0.6 on the unthinned plot, 1.2 under moderate thinning, and 2.6 under intensive thinning. The highest reproductive potential was observed in clones of intermediate, late-intermediate, and early-intermediate phenological forms, with mean fruiting scores ranging from 2.7 to 3.1. Late phenological forms exhibited the lowest reproductive rates (2.1). The summarized results indicate that thinning in clonal seed orchards of Quercus robur significantly enhances reproductive activity and increases seed productivity by 3-4 times compared to unthinned stands. The effect of thinning becomes evident 3-4 years after the intervention. These findings confirm the efficiency of thinning as a silvicultural method for regulating seed production in Quercus robur under the forest-steppe conditions of Ukraine, particularly in the context of ongoing climate change and decreased moisture availability.