Prodromus of the vegetation cover of the southern part of Khortytsia Island (floodplain ecosystems that underwent transformational changes following the destruction of the Kakhovka Reservoir due to the blasting of the Kakhovka Hydropower Plant dam by Russian occupying forces in 2023), based on the results of surveys conducted in 2024–2025.

This repository provides primary vegetation plot (relevé) data and a synoptic phytosociological table for the southern (floodplain) part of Khortytsia Island (Ukraine), documenting vegetation patterns under rapid environmental change following the destruction of the Kakhovka Reservoir in 2023. The dataset includes 878 geobotanical relevés collected during 2024–2025, with their spatial distribution shown in the accompanying figure, and a prodromus-style synopsis of the vegetation units recorded in the study area. The synoptic table summarizes species occurrence (percentage frequency) across vegetation units and highlights diagnostic species, with statistically significant fidelity (P < 0.05) indicated and diagnostic taxa marked with an asterisk. Vegetation sampling followed the Braun–Blanquet approach in 4 × 4 m plots; relevés were classified using TWINSPAN (pseudospecies cut levels 0%, 2%, 5%, 10%, 20%). Diagnostic value was assessed using a fidelity index based on Pearson’s phi coefficient with correction for unequal group sizes. These materials are intended for reuse in vegetation classification, ecological interpretation, and comparative studies of floodplain and disturbed habitats in Eastern Europe.