PONDS FLORA OF THE FIELD BASE “SUNOGA” (PAPANIN INSTITUTE FOR BIOLOGY OF INLAND WATERS RAS, NORTH-WEST PART OF YAROSLAVL REGION)

Species richness of aquatic vascular plants (hydro- and helophytes) was revealed in 26 ponds of the field base “Sunoga” (Papanin Institute for Biology of Inland Waters RAS, Yaroslavl Region) in September 2023 and July 2024. In all, we found 34 species and hybrids. Our data were compared with the results of the previous survey, performed in 1996–2003. This comparison revealed that we found for the first time for the ponds of the field base not less than 8 species and hybrids (Ceratophyllum demersum, Lemna trisulca, Myriophyllum verticillatum, Nymphaea candida, Potamogeton × nites, P. trichoides, Sparganium emersum, Utricularia × neglecta) and failed to find two previously reported taxa (Limosella aquatica and P. × angustifolius). Number of registered aquatic taxa in each pond in 2023 and 2024 does not differ significantly. Similarity of flora of different ponds in each of the two years was low (pairwise Jacquard coefficient usually does not exceed 0.4). Only several pairs of ponds (different in 2023 and 2024) were more floristically similar (Jacquard coefficient: 0.6–0.8), but we did not manage to find any factors, uniting groups of floristically similar ponds. Data for 2023 and 2024 revealed pronounced fluctuations of flora of each pond which should be mainly caused by instability of their water level. Due to the common water supply system, ponds of the field base probably should be treated as parts of one aquatic ecosystem, with exchange of plant diaspores between them. Unlike separate ponds, the entire pond system of the field base was characterized by rather stable aquatic flora, even during the last quarter of a century.