Diversity and dynamics of tall-herb meadowsweet-meadows under the influence of the floodplain xerophytization in the Desna river basin
The paper presents the results of a study of the phytocoenotic diversity of wet meadows and communities, forming in their place as a result of xerophytization of the Desna River floodplain (Bryansk region). Communities of the association Lysimachio vulgaris-Filipenduletum ulmariae Balátová-Tuláčková 1978, described in the floodplain in 1984-2005, were assigned to the only subass. L. v.-F. u. typicum. After a floristic comparison, a number of grazing communities were identified as the independent subassociation L. v.-F. u. deschampsietosum cespitosae subass. nov. hoc loco. A survey conducted in 2018-2019 showed that, due to a decrease in runoff, short and irregular floods of the last decade, a change in the floristic and phytocoenotic diversity of meadowsweet-meadows is observed in the locations of these meadows. In their place, hygro-mesophytic communities with Alopecurus pratensis are formed and the positions of meadow species of the order Molinietalia and the class Molinio-Arrhenatheretea are increased. Such communities are assigned to the new subassociation Poo palustris-Alopecuretum pratensis filipenduletosum ulmariae subass. nov. hoc loco. Ecological assessment of the habitats of plant communities was carried out using H. Ellenberg’ volumes.