Determination of the species structure of phytocenoses of the natural age oak forest of the Dendrological Park "Olexandria" of the National Academy of Sciences of Ukraine
The modern species composition of woody plants of the centuries-old oak grove of the State Dendrological Park "Olexandria" of the National Academy of Sciences of Ukraine was studied. The work was carried out as part of the study of the dynamics of stands of oak phytocenoses under conditions of anthropogenic load, technogenic pollution and weather fluctuations. It has been established that the oak grove of the arboretum with an area of 446 hectares out of 2000 oaks is a complex multi-species planting. The floristic core of the oak forest consists of the main forest-forming species characteristic of the Right-Bank Forest-Steppe of Ukraine: Quercus robur, Acer platanoides L. and Acer campestre L., Fraxinus excelsior L., Tilia cordata Mill., Carpinus betulus L., Ulmus scabra Mill. The role of the dominant species and edificator was retained by Quercus robur. In the worst growing conditions, monodominant stands are formed. In more favorable ecotopes in the upper tree layer, the participation of Quercus robur is 70–100 %, and its codominant satellites (Acer platanoides, Tilia cordata, Fraxinus excelsior) are 10 % each. All oak forest phytocenoses have a well-developed multi-species second tree layer: Acer platanoides (15–80 % in various phytocenoses), Acer campestre (10–30 %), Tilia cordata (10–60 %), in some phytocenoses Fraxinus excelsior (10–20 %), Ulmus scabra (10–20 %), Carpinus betulus (30 %). The group of asectators is diverse and is represented by small species, local and adventive species, introducers, including invasive species. A characteristic feature of the oak forest is its exorbitant crushing, which, along with the massive introduction of introduced species, caused a powerful ecotonization of the oak forest and formed the cells of the greatest mortality of Quercus robur. The conducted studies establish the modern species composition of the oak forest and are the basis for the study of succession processes in oak forest phytocenoses.