Studies were carried out on four stationary transects laid in the Volga–Akhtuba floodplain by the Caspian expedition of Moscow State University in 1954—1955. The transects were reexamined in 1982 and in 2008–2013. The occurrence of the most common plant species in each of the three study periods was assessed. It was established that xerophytization and ruderalization of the flora occurred on all transects. The severity of these processes was not the same on different sections of the Volga–Akhtuba floodplain. They were most significant near the Volgograd hydroelectric power station and in places of valley narrowing. The main cause of vegetation xerophytization and ruderalization was the decrease in the height and duration of floods after regulation of the Volga flow, the high local pasture, and the recreational load. In the northern part of the floodplain, significant changes in the vegetation cover were made by invasions of adventitious species in natural phytocenoses: Fraxinus pennsylvanica, Bidens frondosa, Conyza canadensis, and Xanthium strumarium s. l.

The database EU-RU-002 of the Lower Volga valley vegetation plots has been analyzed. The database contains the characteristics of 15029 relevés located in the region in the period from 1924 to 2013. Two associations, Alismato‒Salicornietum Golub 1985, and Crypsido aculeatae‒Salsoletum sodae ass. nova, have been discovered. These associations include halophytes and glycophytes on the same sample plots. Analysis of water extracts from soil samples made it possible to determine significant dynamics of the toxicity of a soil solution during the year. These changes are related to the hydrological regime of the Volga River.

Vegetation dynamics was assessed using the data of repeated observations (1979–1981, 2011) along transects established in the mid-delta area of the Volga River. In 2011, we noted changes in the vegetative cover that indicate new features in the economic use of foraging sites, an increase in moisture content, and a reduction in soil salinity.

The floristic composition of plant communities dominated by Carex acuta in the northern Volga-Akhtuba floodplain has been analyzed over the period from 1928 to 2009. It has been shown that, in 2008 to 2009, some hygrophytes disappeared from these phytocenoses; simultaneously, their composition was enriched with mesophytes and adventive species. Ramenskii’s ecological scales have indicated a decrease in water supply to habitats of the communities studied.

Analysis of repeated observations (1955, 1971, 1982, 2010) on the transect crossing the Volga-Akhtuba floodplain near Hosheutovo village in the Astrakhan region was implemented. Local xerophytization of vegetation was found in the vicinity of farms and dams in 2010.

The analysis of floristic dynamics of meadows composition of northern part of the Volga-Akhtuba floodplain for the period from 1928 to 2009 was made. The increase in floristic richness of the meadows accompanied by the phenomena of plant invasions, xerophytization and pasture digression were found.

Results of processing releves by Rameskiy indicator values and DCA-ordination indicated processes xerophytization and pasture degradation of vegetation in the northern part of the Volga-Akhtuba flood-plain.

Phytosociological database of Lower Volga Valley was generated in Institute of Ecology of the Volga River Basin of Russian Academy of Sciences. By the middle of 2009, the database included a total of 9,659 releves, recorded on the territory of the Volga-Akhtuba flood-plain and Volga river delta. The characteristic of the database has been made.

The measure of a solar radiation fixed in the rice crop rotation and the amount of energy required to create and sustain this agroecosystem in the Volga estuary have been researched. The low efficiency in the conversion of the land of the Volga river delta to intensively used arable has been established.

Coastal plant communities of Taman' Peninsula were studied. New syntaxa of class Cakiletea maritimae were described on the coast of the Sea of Azov: They are the alliance Cakilo euxinae-Crambion maritimae and the association Cakilo euxinae-Crambetum maritimae. The revision of plant communities of the order Euphorbietalia peplidis in east part of its area has been made. The following syntaxa were established: Cakiletum euxinae, Eryngio maritimi-Cakiletum euxinae, Cakilo euxinae-Salsoletum kali, Cakilo euxinae-Lactucetum tataricae, Cakilenalia euxinae and Euphorbienalia peplidis.