DISTRIBUTION OF POLYSTICHUM ACULEATUM ON THE SLOVECHANSKO- OVRUCHSKYI RIDGE

During expedition on the Slovechansko-Ovruchskyi ridge in 2016–2018, we discovered new location of regionally rare species Polystichum aculeatum. This fern usually belongs to the mountain flora. New findings of plant species require additional research of its coenotic and ecological characteristics. We have found that the population of plants is a stenotope for most environmental factors. The zone of tolerance for this species is wider than we previously thought. This increases competitive capabilities of Polystichum aculeatum in comparison with other species that have a wide ecological plasticity in similar habitats. Polystichum aculeatum species of plants is located in a conditionally different habitat. We can see many similarities in microrelief. Its habitat includes the slopes of loess beams that have a predominantly northeastern exposition. The angle of slope beams ranges from 30° to 75° with an average of 60°. The plants are located at 3–4 meters height above the bottom beams. Depth relative to the beams flange is 3–7 meters with an average value of 5.17 m. The orographic conditions of the Slovechansk-Ovruch ridge are very diverse, but Polystichum aculeatum can be found only in the specific conditions of the microrelief. Polystichum aculeatum is mesophytic, hemihydrocontrastophobic, subacidophilic, semieutrophic, gemicarbonateophobic, heminitrophilic, subaerophilic, submezotermic, gemioceanic, subcriophytic, shade-tolerant plants. The Polystichum aculeatum can withstand moderate anthropogenic pressure. It may exist in oligohemerob and mesohemerob conditions. Its conservation status is sufficient to preserve the basic characteristics of the population. The floral environment of the species consists of 53 representatives of higher vascular plants. The flora of broadleaf forests predominates. There is a large number of ferns (5 species). The species meets at the stage of autogenic succession, which corresponds to the stage of derivatives or indigenous forests.