INFLUENCE OF SINGLE TREES ON FLORISTIC DIVERSITY OF STEPPE MEADOWS AND POPULATION STRUCTURE OF SOME RARE PLANT SPECIES

In the zone of broad-leaved forests European Russia, steppe meadows have been preserved showing rich floristic composition and making a significant contribution to biological diversity territories. Bryansk oblast is one forest regions in Russia where such are found. Here, with high large number rare plant species survived. Trees from surrounding areas constantly encroaching on these meadows. Most young trees die regular grass fires economic activity. However, some individuals survive reach generative state, becoming relatively resistant ground fires. The influence single was studied at two levels living system organization – coenotic population levels. Polydominant polydominant were level; coenopopulations Iris aphylla, Anemone sylvestris, Anthericum ramosum level. Collecting material, we used different methods: geobotanical, demographic, measurements environmental factors (illumination, slope steepness, frequency fires). found be middle part steep slopes unsuitable for haymaking grazing subjected infrequent These communities stable model species. Ontogenetic spectra ramosum, aphylla complete left-hand type maximum individuals. Single (Quercus robur, Tilia cordata) controversial vegetation On hand, introduction trees, increases. This due fact that offer resting places shelter birds spread diaspores. other mature shade herb cover. leads cover reduction occurrence dry meadow species, as well affects their structure. ontogenetic spectrum sylvestris still complete, whereas becomes incomplete, unfinished.