Xerophytization of the Flora and Vegetation in the Northern Part of the Volga–Akhtuba Floodplain

• Published in: Russian journal of ecology 2021, Vol.52 (1), p.18-26
• Main Authors: Chuvashov, A. V., Golub, V. B.
• Format: Article
• Language: English
• Subjects: Biomedical and Life Sciences; Ecology; Environment; Life Sciences
• ISSN: 1067-4136; 1608-3334
• DOI: 10.1134/S1067413621010033

— Data are presented on the results of geobotanical studies along a 27.7-km permanent transect across the northern Volga–Akhtuba floodplain on which 88 geobotanical sampling plots are located. The transect was established in 1955, before the largest hydroelectric complexes were built on the Volga. As a result of their operation, the annual average floodwater discharge to the Volga–Akhtuba floodplain has decreased by 10–15% since 1959, amounting to 40–45% of the total annual water discharge. The water released from the Volgograd Reservoir falls from high height, has much kinetic energy, and its impact leads to deepening of the Volga riverbed in the northern part of the floodplain. Therefore, the same volumes of releases from the reservoir during floods result in increasingly lower rise in water level and, as a consequence, reduction in the inundated floodplain area. The results of surveys in 1982, 2008, and 2019 showed that xerophytization of vegetation in the floodplain region crossed by the transect has progressed during the 64-year period. Changes in the vegetation caused by the impairment of moisture conditions in the floodplain are accompanied by successions of phytocenoses resulting from invasion by new species. Among them, the North American species Fraxinus pennsylvanica has the most significant effect on the natural vegetation.