Vol 9, No 1 (2019)

The steppe zone occupies large area in the South of the European Russia. Part of the Caspian Lowland belongs to the desert zone. Some researchers distinguish the semidesert zone along with the steppe and desert zones. The paradox is that there is no semidesert type of vegetation, there are no typical elements for the semidesert, but the semidesert is considered as a separate zone.

In long-term studies (21–30 years in the floodplain ecotype and 12 years in the ecotype of sandy terraces), the duration of the main phenological phases of the development of black alder (Alnus glutinosa Gaertn.) plants was determined. The influence of the edaphic factor is manifested in the dates of the termination and duration of individual phenophases. In the sandy-terrace ecotype, growth buds are laid 8 days earlier, the leaves fall 2 weeks earlier, and the period of shoot development is longer than 7 days. Statistically significant differences between the ecotypes (t_f = 2.12–7.16 > t₉₅ = 2.01–2.03) were revealed in the duration of flowering periods and leaf development. In each ecotype, the strongest dependence of the phenological phase duration was revealed under the combined influence of the heat and moisture conditions of the corresponding period (r_{x (yz)} = 0.55–0.99). An identical phenological spectrum in the two studied ecotypes is observed in years with a 1.5- to 2.0-fold excess of the mean multiyear value of the hydrothermal coefficient.

Experimental hydrogeochemical studies on water-balance areas in field and laboratory conditions are considered. The principles of the selection and equipment of water-balance areas and laboratory facilities, as well as the selection of the main pollutants and the chemical composition of indicator solutions and water for the washing of pillars and monoliths, are established. A sequence of experimental procedure in field and laboratory conditions is proposed. A method to determine the salt transfer parameters with the use of mathematical models of salt macrodispersion (three methods: reference curves, moments and graph-analytical), microdispersion, and dissolution is considered. The technique of experimental studies of salt transfer was tested on the northern Ershov irrigation system (NEIS) in the Saratov oblast.

The agrochemical properties of humus-accumulative horizons of irrigated soils on the key site of the Svetloyar irrigation system in Volgograd oblast are analyzed. The field layout before the operation of the irrigation system and a long period of irrigation resulted in redistribution of the carbonate material. Its concentration in the upper part of the soil profile amounted 5–13%, which led to the formation of a dense soil crust and alfalfa crop failure areas (mortality spots). These sites are well detected on the materials of satellite imagery. In the over-45-year period of irrigated arable land exploitation, there has been a significant decrease in the humus content in comparison to arable, nonirrigated lands. The humus content in the soils of the key sites averaged 1.23% and approached the minimum acceptable level, according to (Metodicheskie…, 2003). The soil degradation is caused by the overall low level of farming culture and the long-term use of the surface irrigation method. The content of mobile phosphorus (20–102 mg/kg) and exchangeable potassium (316–806 mg/kg) varied widely from medium to very high levels in these soils.

The biodiversity of rare, endangered, and recovering bird species has been assessed for the arid and semiarid regional biomes of Russia (the Red Book of the Russian Federation and the IUCN Red List of Threatened Species (Krasnaya kniga..., 2001; IUCN, 2018)). It is shown that 104 protected species of the 118 species that live in the entire territory of Russia inhabit arid and semiarid territories. The paper identifies a group of rare species that are not or are poorly provided with protection at the level of reserves within the arid and semiarid regional biomes of Russia. The results of the study can be used to assess the regional biodiversity of rare and endangered bird species and to develop effective measures to increase the level of their protection.

Lake Issyk-Kul is one of the largest high-altitude and brackish lakes of continental origin. The long-term dynamics of the chemical composition of the water of its basin is evaluated and analyzed based on data from 1932, 1977, and 1986. The average long-term dynamics of water salinity is determined based on data from 1928, 1960, 1980, 2000, and 2014. The predominant ions of the lake water are sulfates, chlorides, sodium, and magnesium. The predominant cations are Na⁺ and Mg⁺ , and the predominant anions are Cl^– and \({\text{SO}}_{4}^{{2 - }}\). Sulfates predominate in the chemical composition, so the water belongs to the sulfate class and the chloride–sulfate–sodium–magnesium mineralization type. The water in the lake is alkaline; its pH ranged from 7.95 to 8.82 in 2015. The salinity of Lake Issyk-Kul is 6.22 g/L. The study of the hydrochemistry of natural waters is of great practical importance for various sectors of the economy, since the chemical composition of water is taken into account for all types of water supply and use. Hydrochemical research is also of increasing interest due to increased water-reservoir pollution and anthropogenic activity.