Caucasian State Natural Biosphere Reserve named after Kh.G. Shaposhnikov

The chemical composition of the waters of 31 springs located in the basins of the Mzymta and Sochi rivers on the southern slope of the Caucasus Range was studied. Both water-bearing fractured carbonate rocks and water-resistant mudstones and igneous rocks are developed here. In addition, the region is characterized by the development of mineralization zones and deposits of thermal hydrogen sulfide waters. Four types of waters have been identified: I) hydrocarbonate calcium, II) hydrocarbonate-sulfate calcium-magnesium, III) hydrocarbonate-sulfate calcium-sodium, IV) hydrocarbonate-chloride-sulfate calcium waters. Due to the geochemical features of regional rocks, all types of waters are characterized by high contents of Se and rare earth elements (REE) and low concentrations of Tl, Zr, Th, and Fe. The first type of waters is associated with fractured carbonate rocks, and due to their good solubility and water permeability, it differs from other types of waters by increased concentrations of Se and REE by factors of 2.3 and 2.6, respectively. The second type, distributed mainly in argillites, is distinguished by relatively low contents of Se, REE and other elements, which is due to the lower water permeability and solubility of argillites compared to carbonate rocks. The third type is characterized by the additional presence of excess elements Ba, Li, Rb and B in the composition, which is associated with the influence of a deposit of hydrothermal mineral waters. Igneous rocks, being the least permeable and less rich in chemical elements than mudstones, influence the formation of groundwater with the lowest concentrations of elements. The low permeability of igneous rocks is confirmed by the analysis performed using the hydrogeochemical Gibbs diagram, indicating that the precipitation factor is superimposed on the formation of these waters. REE for all types of waters are characterized by similar fractionation inherited from the rocks of the region (medium REE heavy REE light REE). The total amount of rare earth elements and their fractionation patterns can be used as a reliable criterion for the interpretation and typification of fresh groundwater.

All of them are local endemic species distributed only in the West Caucasus (Russia: Stavropol and Krasnodar regions, Adygea; Abkhazia). A key to 11 species of the subgenus Pliadonus Reitter, 1912 is given. Few host plants are established for O. starcki, O. pseudobrachialis and O. granulatissimus. Otiorhynchus pseudobrachialis was collected for the first time after its description by E. Reitter in 1914; all of specimens were found only on Epimedium colchicum (Boiss.) Trautv. (Berberidaceae). Otiorhynchus starcki and O. granulatissimus occurr on different plants, from which on Epimedium colchicum O. starcki was found in the south part of its range and O. granulatissimus in the northwestern part of Abkhazia. In our opinion Epimedium colchicum together with O. starcki, O. pseudobrachialis and O. granulatissimus represent the autochthonous nature complexes in the West Caucasus. The holotype of O. fortispinus Reitter, 1909 was examined, and lectotypes of O. starcki, O. pseudobrachialis, O. granulatissimus and O. dentitibia are designated.

Revision of the type series of Bisetifer cephalotus Tanasevitch, 1987, shows this species to be heterogeneous and, besides the nominate form, the series to contain another, very similar, new species, B. gruzin sp.n. The female, originally described as corresponding to the male of B. cephalotus, is actually the female of the new species. The true female of B. cephalotus is described for the first time. Fresh samples from the Krasnodar Province, southern Russia and from Georgia show that B. gruzin sp.n. seems to be much more widely distributed in the Caucasus than B. cephalotus.

The occurrence of a density compensation effect (DCE) has been estimated in north Caucasian areas of extreme habitats occupied by communities of vascular plants, mosses, and lichens. The species densities have been estimated according to their frequency. The correlation between species number and frequency in the studied areas has failed to confirm the assumption that extreme environmental conditions alone is responsibile for the DCE, at least locally.

It is known that the local species richness of biological communities with a high dominance level is usually lower than in communities with a low dominance. Taking into account the complex nature of the dominance phenomenon, the causes underlying this correlation can be diverse, yet they commonly remain beyond the scope of performed analyses. The goal of this work was to consider this issue by the example of West Caucasian tree and insectivorous bird communities. The results demonstrate that the correlation between the dominance level and local species richness to a considerable degree (50–60%) is a consequence of preemption of a larger or smaller amount of resources by the dominant species. However, the ecological processes determining the general pattern of resource distribution among species also play a certain role in these relationships, as well as the size of the species pool, which concurrently influences both the local species richness of communities and the number of potential dominants. The relative contributions of various mechanisms to the establishment of the considered correlation depend on the degree to which the rank structure of species abundance in communities matches the geometric series model.