The results of our ecological-phytocenotic assessment of the natural coenopopulations of the rare (in Bashkortostan Republic) species Dictamnus gymnostylis Steven are given. In the Southern Urals, the species is on the northeastern border of its habitat. The ontogenetic, demographic and vitality structures of 20 coenopopulations were studied, the existence optima were found. The majority of the surveyed coenopopulations of D. gymnostylis have densities within 1 - 10 ind./sq.m and an incomplete ontogenetic spectrum, the basic ontogenetic spectrum being centered. The vitality type of the coenopopulations changes from prospering to depressive. The status of the species in its isolated habitat fragment in the Southern Ural is satisfactory; no additional measures for its protection are required.

Molecular-genetic typing was done for voles in the vicinity of the Pslukh forest station (the south of the Caucasus nature reserve), the Krasnaya Polyana, and the Utrish nature reserve (the Abrau peninsula). Based on the nucleotide sequence of the mitochondrial cytochrome b gene, the voles from the Krasnaya Polyana and Pslukh station were attributed to Robert’s snow vole (Chionomys roberti), whereas the animals from the Utrish nature reserve belong to the Eastern-European vole (Microtus rossiaemeridionalis). Robert’s snow voles belong to the Northern Caucasian phylogenetic branch of the species. Our analysis of body measurements of the voles from the Krasnaya Polyana and Lazarevsky district (without molecular examination) has shown that these animals most probable also belong to Robert’s snow voles rather than to the Gudaur snow voles as they were erroneously attributed earlier. Data on the ecology of Robert’s snow voles in the region are presented.

An attempt was made to estimate the impact of major limiting factors on changes of the vimba population size in the Volgograd reservoir. The vimba population size in the reservoir is already close to its limit by one hypothesis, based on the accessibility of spawning area resources. A 15-fold increase in the vimba population size is possible for at least two decades by another hypothesis, providing for the population restriction by food resources. Rather different predictions of the ultimate population size and the time of its achievement are derived from the considered hypotheses about the factors limiting the vimba population growth in the reservoir. It is only possible to check these hypotheses by further research.

Based on the literature, non-published and survey data, information on the occurrence of anadromous sturgeons after the regulation of the Don River downstream and upstream of the Tsimlyansk Dam is given. There were two peaks of mature adults approaching the dam, namely, in the 1950s and 1980s. The first mass peak was associated with the wild population existed then; the second one was a result of mass artificial breeding. At the first stage, the sturgeon (Acipenser gueldenstaedtii Brandt et Ratzeburg, 1833) and beluga (Huso huso (Linnaeus, 1758)) prevailed below the dam; at the second one, just the sturgeon did. Since 1955, only 21 individuals of anadromous sturgeons were transported through the dam by a fish ladder. During 1952-1961, 1,145 individuals were transported into the reservoir, including 218 belugas. Separate beluga individuals were transported later on as well. There is evidence of the presence of young beluga individuals from natural spawning in the reservoir before the 1970s. The latest known adult sturgeon and stellate sturgeon (Acipenser stellatus Pallas, 1771) in the reservoir were noted in the 1980-90s. Separate beluga individuals have been met until now. The youngest of the noted individuals belong roughly to the generations of the early 1990s. It is concluded on the existence of an extremely low-abundant landlocked form of the Azov beluga in the reservoir.

The intrapopulation and interpopulation variability of ten counting features of the external morphology and skeleton in individuals of the crucian carp from three small ponds differing by their anthropogenic pollution level was studied. A statistically significant trend of the decreasing average population values with increasing the water salinity in the small ponds was revealed for five non-metric osteological signs.

The coenopopulations of Hedysarum grandiflorum Pall. in the southern Volga Upland within the administrative boundaries of the Saratov region were studied for the first time. The relief, parent rocks and soils in their habitats were characterized. Main environmental scales were supplemented by new data. Tolerance amplitudes by vital environmental factors were revealed. Adaptation features of this species to its environment are presented. H. grandiflorum is shown to be a quite stenobiontic species. A relationship between the species’ vitality and the parent rock depth, soil moisture, wealth and salinity was found.

The spatial distribution of the Great Spotted Woodpecker in Saratov city was studied in the winter seasons of 2004-2012. The bird distribution was either aggregated or random. The multi-year wintering sites of the Great Spotted Woodpecker are associated with the gully network of the suburban woodland park, city parks, forest belts and old gardens. Dependence between the spatial distribution and pine harvest was found. The bird distribution was grouped in productive years and random in lean years, respectively, because of woodpeckers’ movements to the woodland park and built-up areas.

Preliminary data on the Castor fiber activity influence on the ecosystem biodiversity of small rivers in three steppe clusters within the State Nature Reserve “Volga forest-steppe” were obtained. With zooplankton, amphibians and fish as examples, it was shown that after beaver-made ponds had appeared, the abundance of all these groups increased. In old ponds, the fish abundance decreases whilst the amphibian one continues to increase. In drained ponds, the zooplankton and amphibian abundance decreases while the fishes become more numerous, due to the appearance of better flowability.

The Haematopus ostralegus longipes population numbers in the conditions of the middle reaches of the Medveditsa river in the nesting period of 1996 - 2008 was stable, namely, 3 pairs, of which two, rarely three ones, nested annually. The egg laying size was 2-3 eggs. In the course of our many-year survey, a tendency has been established to significant reducing the reproduction success level against the background of transformations of the nesting and feeding stations, which is determined by the long-term tendency to reducing the water content in the river.