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Akatov V.V.,Maikop State Technological University | Akatova T.V.,Caucasian State Nature Biosphere Reserve | Eskin N.B.,Caucasian State Nature Biosphere Reserve
Contemporary Problems of Ecology | Year: 2014

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. © 2014, Pleiades Publishing, Ltd. Source


Akatov V.V.,Maikop State Technological University | Akatova T.V.,Caucasian State Biosphere Reserve | Eskina T.G.,Caucasian State Biosphere Reserve
Russian Journal of Ecology | Year: 2010

The saturation of herbaceous communities with adventive species in the Northern Caucasus has been estimated using as an indicator the number of such species in 0.5-m2 plots. Among factors accounting for variation in the test parameter, consideration has been given to the coverage of the herbaceous layer, the species richness of communities (in 0.5-m2 plots), and the numbers of adventive and indigenous species (in 15-m2 plots). The field data have been processes by methods of ordinary and multivariate regression analysis. The results show that variation in saturation with adventive species between small areas of herbaceous communities largely depends on the number of such species in larger areas, their species-holding capacity, and the level of completeness of communities. © 2010 Pleiades Publishing, Ltd. Source


Grigor'ev V.P.,South Federal University | Popova A.A.,Maikop State Technological University
Protection of Metals and Physical Chemistry of Surfaces | Year: 2011

The possible relationship between the critical passivation potentials, zero-charge potentials, and flat band potentials for transition metals of groups IV-VI of the periodic table in a series of alcohol solvents; their adsorption on a metal surface results in the transition of the metal into the passive state upon a certain shift in the potential with respect to E q = 0. © Pleiades Publishing, Ltd., 2011. Source


Akatov V.V.,Maikop State Technological University | Akatova T.V.,Caucasian State Nature Biosphere Reserve
Russian Journal of Ecology | Year: 2015

The number and occurrence of plant species are compared in isolated with forest and nonisolated areas of subalpine meadows in Western Caucasus alpine massifs. It is shown that isolation of meadow communities on small isolated massifs (0.01–36.5 km2) for about a thousand years has led to a decline in their species richness. However, this process is mainly due to the loss of rare plant species and was not accompanied by the density compensation effect. It is suggested that a wide manifestation of compensation processes requires a period of time significantly longer than the isolation time for most fragments of anthropogenic communities. © 2015, Pleiades Publishing, Ltd. Source


Akatov V.V.,Maikop State Technological University | Perevozov A.G.,Caucasian State Biosphere Reserve
Zhurnal Obshchei Biologii | Year: 2011

Dominance level is traditionally expressed as a ratio between the number of individuals belonging to the most abundant species and the total number of individuals in a biological community. It is known that local species richness is usually higher in biological communities with high dominance level than in communities with low one. Taking into account a complex nature of the dominance phenomenon, the underlying reasons (or mechanisms) may be diverse: 1. Dominance level may be determined by bioecological traits of the most abundant species as well as stochastic impacts. The more abundant is dominant species, the fewer amount of resources goes to concomitant species and, therefore, the lower is community species richness. 2. The part of community resources used by the dominant species may be not a special case but can be a reflection of general pattern of resources distribution among species under specific environmental conditions. Correspondingly, in communities with higher dominance level there might be more "strict" distribution of resources among concomitant species, which, in turn, might influence community species richness. 3. The relationship between dominance level and community species richness may be caused by their dependence on the third variable, namely regional species pool. In the present paper we tackle the problem using arboreal and insectivorous bird communities of the West Caucasus as a case study. The data were collected in different altitudinal belts on both macroslopes of the western part of the Main Caucasian Ridge. The number of tree species and individual trees was counted within homogenous patches of arboreal phytocenoses 300 m2 in area. Species richness and numbers of insectivorous birds were estimated in course of route surveys with a route length being about 5 km. An analysis of empirical data was carried out using univariate and multiple correlation-regression techniques. The results indicate that the relationship between dominance and local species richness is determined to a large extent (by 50-60%) by a dominant taking over greater or lesser amount of the resources (mechanism 1). The role of two other mechanisms (2 and 3) is not so prominent - together, they are responsible for 25-40% of the relationship power. Relative contribution of different mechanisms to the relationship under consideration depends on conformity of species abundance rank structure with the geometric series model. At those sites where this conformity is manifested, the relationship between dominance level and species richness is due mainly to mechanisms 1 and 2, i.e., is determined by local processes. At other sites, where the conformity of species abundance rank structure with the geometric series model is not so good, a certain role belongs to the size of regional species pool (mechanism 3). Source

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