Том 8, № 4 (2018)

We continued the complex ecological studies in the Lower Volga Region that we started in 2014 in order to investigate the current state of floodplain terrestrial ecosystems and to describe the tendencies in the transformation of the natural environment and the responses of terrestrial ecosystems to changing climate conditions and the influence of anthropogenic factors. The study was conducted with the original two-step method for the estimation of disorders in terrestrial ecosystems after changes in the water content of studied areas. The first step included the determination of possible changes in the water content based on an analysis of long-term annual changes in climatic and hydrological data. The second step included the estimation of disorders in the ecosystems and landscapes based on various biological parameters. We determined the main factors of changes in the abiotic (hydrological and climatic) components of ecosystems in the Lower Volga Region influencing the transformation of landscapes. We described the main causes of changes in a separate component of terrestrial ecosystems related to the increased water flow rate of the winter low-water period and winter runoff, which contribute to a higher level of gleying throughout the entire soil profile and to the degradation of floodplain ecosystems (along with climatic changes).

A long period of freezing and drying of the soil profile and frequent seasonal and daily temperature fluctuations lead to the formation of chestnut soils featuring slightly condensed and developed aliphatic humic acid (HA) chains, which makes the soils unstable. The current environmental condition of chestnut soils confirms this; the area of degraded arable and grazing lands in the Republic of Buryatia is significant. Their location in intermountain basins often results in a high vulnerability to deflation processes, leading to dehumification. This adverse phenomenon is currently amplified by global climate change, which intensifies the aridization rates. The noted complex of factors determines the specific composition of regional phytocoenoses, which are highly ligninoficated and depleted of protein components; this affects the structure of humic substances and determines the number of specific features of the local humus, which is distinct from that in similar soils of other regions.

The current state of land use in the Republic of Kalmykia is considered. An increase in degraded lands with respect to salinity and erosion is shown. An increase in the species composition of forage crops via the introduction of amaranth is substantiated as a way to increase the productivity of degraded arable lands. The great advantages of amaranth include its high nutritional value and good forage digestibility. Amaranth can be very important as a high-protein forage crop; it provides quality of forage production for the stable development of animal husbandry in the Republic of Kalmykia.

We have developed a technique to assess the state of shore ornithocomplexes that can be used for any artificial water bodies to reveal disturbances in their functioning and use. The article presents data on some artificial reservoirs of the dry-steppe zone in the south of the European part of Russia (Republic of Kalmykia). Our research has revealed the main factors of the environmental influence (water factor) on reservoir avifauna and determined the main indicators of assessment (population abundance and density). Analysis of data on the state of shore ornithocomplexes of the steppe reservoir (dynamics of the species diversity, numbers, and abundance of birds of the wetland semiaquatic complex) has shown their dependence on the water factor (reservoir drying/flooding). In light of the increase in anthropogenic impact, it is relevant to consider changes in the biodiversity of the ornithocomplex of some inland reservoirs in Kalmykia, such as Sarpa and Deed-Khulsun, in the period from 2008 to 2015. An environmental characteristic and assessment of the current state of their populations are given according to the developed technique. Recommendations on managing the hydrological regime of reservoirs are given for the maintenance and preservation of bird populations of the wetland semiaquatic complex in these reservoirs.

The activity of protein degradation enzymes in rodents under temperature stresses caused by a body temperature rise (hyperthermia) up to 42°С is studied under the conditions of hyperarid regions of arid territories. The heat stress was induced in a special chamber; water at a temperature necessary to raise or lower the body temperature passed through the chamber casing. Regardless of body temperature, the activity of neutral proteases (ANPs) of the liver decreases in both cases. The mechanisms leading to a decrease in ANP with an increase in body temperature are different, since the degree of decreased enzyme activity in this case is several times higher than with low-temperature stress. With hyperthermia, the ANP of all grades of thermal regime is significantly reduced, both in comparison with the control and with hypothermia, except for the incubation temperature of 10°C. The changes occurring in the rodent (in the liver) are evidence of the degree of influence of arid climatic conditions on the adaptability of the considered animals to climate warming.

Most of the hypersaline lakes located in the arid part of the Crimea have been undergoing anthropogenic transformations. We concentrate on the impact of the established water storage reservoir on the marine Kyzyl-Yar Lake (Western Crimea) over the period from 1985 to 2017. As a result of water seepage from the reservoir, the lake salinity decreased from 162 g/L in 1985 to 2–3 g/L in 2005 and subsequently remained steady at this level. Over 20 years, the lake changed from a hypersaline to freshwater lake. The accompanying changes included an altered ratio of ion concentrations in the water column and interstitial waters and increased Ca²⁺/Na⁺ and \({{{\text{SO}}_{4}^{{2 - }}} \mathord{\left/ {\vphantom {{{\text{SO}}_{4}^{{2 - }}} {{\text{C}}{{{\text{l}}}^{ - }}}}} \right. \kern-0em} {{\text{C}}{{{\text{l}}}^{ - }}}}\) indicators. Substantial shifts occurred in the structure of the biological diversity and conditions of the bottom deposits, such as the disappearance of branchipoda crustaceans of the genus Artemia, which had been practically the only representative of the local fauna before, and the dominance of new species Cladocera and Cyclopoida in plankton.