Karyological aspects of the Lower-Volga rodent fauna. – Baskevich M.I., Kozlovski A.I., Oparin M.L., Savinetskaya L.E., Cherepanova E.V., Pimenova T.I., Sokolenko O.V., Khlyap L.A. – Chromosomal data for a number of rodents in the Lower Volga region are presented. The following species and forms are considered: Sicista strandi, Sicista subtilis, Microtus rossiaemeridionalis, Microtus arvalis «obscurus», Apodemus (Sylvaemus) uralensis, Allocricetulus eversmanni, Mus musculus. Some of these species (Sicista strandi, sibling-species of common voles, and Apodemus (Sylvaemus) uralensis) have been identified in terms of the chromosomal approach only. The role of this approach for determination of the species composition and intraspecific structure of rodents in the Lower Volga region is analyzed using original and literature chromosomal data.

Key words: chromosomes, fauna, rodents, sibling-species, intraspecific structure, Lower Volga region.

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Macrozoobenthos communities in the temperature gradient of the Balakovo NPS cooling reservoir. – Voronin M.Yu., Yermokhin M.V. – The position and peculiarities of the macrozoobenthos community in different warm-up conditions are considered. Changes of the macrozoobenthos community conditions on putting the second phase of the Balakovo NPS power blocks in operation are forecasted.

Key words: macrozoobenthos, community, cooling reservoir of nuclear power station.

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Halophytic vegetation of the Middle Volga region. – Lysenko T.M. – Some peculiarities of salted soils in different regions of the Middle Volga region are considered. A comparative characteristic of the halophytic vegetation is given.

Key words: salted soils, halophytic vegetation, botanical and geographical zones, Middle Volga region.

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Grassflies (Diptera: Chloropidae) of the Southern Volga region. – Narchuk E.P. – The research history and grassfly fauna (Diptera, Chloropidae) of the Southern Volga region are discussed together with the species' distribution in their natural zones (forest-steppe, steppe, and semidesert ones). The life habits of larvae and their distribution are given for 97 species. Pests of cereals and fodder grasses are indicated.

Key words: Diptera, Chloropidae, fauna, pests of cereals and fodder grasses, Southern Volga region, Russia.

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Ecological justification of some approaches to standard regulation of the river run-off regime. – Novikova N.M., Kuz'mina J.V., Podol'ski S.A., Balyuk T.V. – Analysis of some ecologo-biological indices of the flood-land ecosystem status and river run-off characteristics has enabled four principal ecological criteria to restrict any regulation of the river run-off to be proposed, namely: (i) recurrence of the maximum run-off should provide the formation of primary landscape elements of flood-lands; (ii) flooding the ecosystems at all the ecological levels with a characteristic frequency and duration; (iii) annual amplitude of ground water level variations characteristic of every element of the flood-land relief; (iv) parts of flood-lands with a constant hydrological regime which provide migration routes to animals and save refugiums of the river basin diversity.

Key words: ecosystems, diversity, stable operation, criteria, river run-off, flooding duration and frequency.

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On changes in the mammal communities in Western Kazakhstan due to long-term alterations of their abiotic conditions. – Okulova N.M., Bidashko F.G., Grazhdanov A.K. – Astro-, geophysical, and climatic processes are closely connected with each other and also with the distribution, number, and population conditions of mammals. 60-year observations at 10 stationers in Western Kazakhstan for some numerous mammal species confirm this idea.

Key words: astro-, geophysical, climatic processes, mammals, specific composition, number, Northern Caspian lowland.

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Ecological distribution of Lepidoptera (Insecta) in Kalmykia. – Saranova O.A., Anikin V.V. – The lepidoptrerofauna of Kalmykia includes 625 species from 42 families. The specific diversification of Lepidoptera complexes of the main phytiums of Kalmykia was studied. Cluster analysis of the lepidopterofauna distribution on 11 main phytiums shows three big clusters, the first, second, and third ones to combine the species of the northern-ergen steppe complex, the semidesert-desert steppe complex, and the salt-sandy-desert complex, respectively. The lepidopterafauna of the third complex is most specific. The fauna under study is a complicated union of different ecological structures. The main role in this union is played by the steppe and desert xerophilous, steppe mesophilous, the fraction on evribionts is also noticeable. Other ecological groups are subordinate.

Key words: Lepidoptera, ecology, distribution, Kalmykia, Russia.

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On deserted steppes of the Lower Volga region. – Safronova I.N. – Deserted steppes are the most xerophytic type of steppes. On placor habitats with light-chestnut soils they are represented by plant communities with bunch grasses (Stipa, Festuca, Agropyron, Koeleria) to dominate and dwarf semishrubs (mainly the species of Artemisia of the Seriphidium subgenus and also Kochia prostrata, Tanacetum achilleifolium, etc.) to codominate. The deserted steppes are poor of species but highly heterogeneous spatially. Vast areas are occupied by halophytic variants of steppes. Dwarf semishrub communities often predominate among the components of complexes, which gives a desert look to steppe landscapes and makes it difficult to draw zonal and subzonal boundaries. Some researchers classify the desert steppe subzone among the semidesert zone rather than the steppe one. Every zone is characterized by its peculiar type (or types) of vegetation. No semidesert type of vegetation is distinguished by most of the Russian geobotanists. Therefore there is no reason to speak of a semidesert zone.

Key words: steppe zone, subzone, semidesert, desert steppes, complexes.

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Spatial variations of the functional structure of soil animal populations in the steppes of European Russia. – Striganova B.R. – Main trends of changes in the functional structure of soil animal populations in steppe ecosystems along the aridity gradient are considered. Against the background of insignificant fluctuations of the abundance levels of soil invertebrates, a reduction of the animal saproblock diversity and a simultaneous increase of the relative weight of plant-root-eating forms take place. Along the zonal-regional transects crossing the steppe zone in the North-South and West-East directions the total soil zoomass tends to decrease as the climatic aridity and continentality increase. But the reduction of the soil zoomass progresses slower than that of the primary production. That is why the loading of animal feeding activity on the living phytomass and mortmass enhances, which results in an increase of the zoogenic activity role in the decomposition dynamics.

Key words: mesofauna, latitude-longitudinal gradient, edapho-climatic conditions, demutation processes, steppe zone.

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Spatial distribution and abundance trends of Dione snake (Elaphe dione) in the north of its Volga habitat. – Tabachishina I.E., Tabachishin V.G., Zavialov E.V. – The northern boundaries of the Elaphe dione habitat in the Volga region have been revealed. Elaphe dione is represented there by stable local populations but its abundance is everywhere low; no trends of it have been revealed. The peripheral habitats are on the territories of the Samara and Ulianovsk regions, which makes it reasonable to insert the species into the regional Red Books.

Key words: Elaphe dione, biotopical distribution, abundance, spread.

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Ecological characterization of background rodent species in steppes of the lower reaches of the Volga and Don rivers. – Tikhonova G.N., Tikhonov I.A., Surov A.V., Oparin M.L., Bogomolov P.L., Kovalskaya Yu.M. – The distribution, population structure, and reproduction of 5 rodent species were studied in the steppe zone of the lower reaches of the Volga and Don rivers during 8 years. In total, 6836 animals were caught taking 61222 trap-nights. 5 types of natural biotops and 5 anthropogenic ones were analyzed. Apodemus uralensis was the most successful species, it lived practically everywhere and reached the maximum population density. Its population structure and reproduction strategy were fluent. Mus musculus preferred anthropogenic biotops while Microtus arvalis did natural dry habitats. Both species are characterized by comparatively stable population structures. Even less adapted to dry biotops were Apodemus agrarius and Microtus rossiaemeridionalis, they featured a high fertility and reproduction along with a high level of mortality. As a result, these species were less abundant and more stenotopic in comparison with the other 3 ones.

Key words: rodents, population structure, reproduction, biotopic distribution, abundance dynamics, adaptation.

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Agrolandscape-ecological division into districts and agrolandscape optimization of the Volga economical region. – Trofimov I.A., Trofimova L.S., Lebedeva T.M., Yakovleva E.P. – New, complete data on the spatial location of landscape systems, the usage of agroecological soil properties, natural and economical features of agrolandscapes, the differential usage of technologies, cultivated plant species and anthropogenic factors were obtained in the course of our agrolandscape-ecological division into districts of natural forage resources in the Volga region. The division of the territory into districts was first performed at a new, higher level of systematicity, attention being focused on the environment-stabilizing and nature-saving functions of forage resources in connection with their productive function, and on the role of forage resources and perennial crops on arable lands in agrolandscape stabilization. Ways of rational nature use in agricultural production, priorities and trends to effectively provide adaptivity, stability, the resource-saving, environment-forming, and nature-preserving roles of agroecosystems, the maximum usage of agroclimatic resources, biological and ecological factors are shown.

Key words: environment-stabilizing components of agrolandscapes, natural-agricultural zones, anthropogenic loads, excessive ploughing up, agroecosystems.

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Distribution features and demographic indices of petty mammals in natural steppe complexes of the Saratov Volga region. – Tsvetkova A.A., Oparin M.L., Oparina O.S., Yemelianova N.V. – The specific composition, some biotopic distribution and abundance features of petty mammals as well as main reproduction characteristics of background species are discussed. A low level of the abundance of xerophilic species was observed. Relatively high indices of specific diversity are characteristic of intrazonal habitats where the teriocomplex core is composed of widely spread and mesophilic species of petty mammals. Apodemus agrarius predominates and shows a high reproduction efficiency. The specific structures of petty mammal communities in natural and anthropogenic habitats in a typical steppe are similar.

Key words: petty mammals, abundance, biotopical distribution, Volga Highland, Yeruslan sands.

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Most important taxons of bloodsucking arthropods as a vector of pathogens in the Lower Volga and neighboring regions. – Chirov P.A. – Ixodid ticks (Ixodidae), horse flies (Tabanidae), and mosquitoes (Culicidae) are the most important taxons of bloodsucking arthropods in the Lower Volga region. They are vectors of pathogens of infection and invasion diseases. Climate warming and man-caused factors may stimulate the development and migration of arthropods to northern regions and promote disease pathogen circulation in new territories. Distribution monitoring of different pathogens is suggested for biological safety.

Key words: Ixodid ticks, Horse flies, Mosquitoes, vector of pathogens, Lower Volga.

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Stability dynamics of the Volgograd reservoir ecosystem. – Shashulovsky V.A., Mosiyash S.S., Malinina J.A., Dalechina I.N., Kotlyar S.G., Filinova E.I. – The opportunity of a complex approach to estimation of the reservoir ecosystem stability is shown. The results of such a study show growth of the general stability forms of the ecosystem during the reservoir's existence.

Key words: reservoir, ecosystem, abiotic factors, biotic parameters, general forms of stability.