Meadow communities of the Middle Ob floodplain over two years under different flooding conditions

The paper presents a comparative analysis of changes in species, ecological and biological composition, dominant species composition, and net primary productivity (NPP) of floodplain meadows in low (2023) and high (2024) flooding years. Meadows in the study area exhibited higher productivity in 2024 compared to 2023. In 2024, NPP increased by 45.6% in the forb-grass meadow, by 37.8% in the sedge-reedgrass meadow, and by 34.5% in the elecampane meadow. Changes were observed in species richness, the proportions of ecological groups, and dominant species composition. The most significant changes were recorded in upland meadows that are not regularly flooded. The productivity of the forb-tussock sedge meadow remained virtually unchanged (an increase of only 1.4%), indicating stability and potentially maximum productivity under these conditions. An increase in NPP was attributed to the increase in both above-ground and below-ground phytomass and correlated with structural shifts in the grass stand toward a higher proportion of moisture-demanding species.