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

Open plant assemblages in shoals of western Caucasian rivers were used as examples to analyze the relationship between the species saturation and the number and total abundance of alien species in non-interactive communities. Invasion of exotic species into highly saturated communities has been demonstrated to be, on average, less probable than their invasion into unsaturated communities. A hypothesis explaining the relationship between these parameters has been put forward. According to the hypothesis, the number of alien species in a specific locality in a community is determined by their ratio to the number of native species in the species pools of these communities; and their mean abundance, by the ratio of the total number of species to the number of individuals in the localities. Both ratios are smaller in saturated biocenoses, which determines a relatively small admixture of alien species in them. © Pleiades Publishing, Ltd., 2010.


Bleyhl B.,Humboldt University of Berlin | Sipko T.,RAS Severtsov Institute of Ecology | Trepet S.,Caucasian State Biosphere Reserve | Bragina E.,University of Wisconsin - Madison | And 4 more authors.
Biological Conservation | Year: 2015

In an increasingly human-dominated world, conservation requires the mitigation of conflicts between large mammals and people. Conflicts are particularly problematic when resources are limited, such as at wintering sites. Such conflicts have fragmented many large mammal populations, making reintroductions in suitable sites necessary. Broad-scale habitat suitability mapping can help to identify sites for species' reintroductions. The European bison is a good example of a large mammal that is restricted to only a fraction of its former range. The goal of our study was to identify and assess potential habitat for European bison in the Caucasus Mountains, which is a part of its former range and has the potential to harbor larger populations. Specifically, we used seasonal presence data from four reintroduced European bison populations and two sets of predictor variables to: (i) map habitat suitability for summer and winter, (ii) characterize habitat based on management-relevant categories that capture the potential for conflicts with people, and (iii) identify candidate sites for reintroductions. We found substantial areas of suitable habitat. However, areas of potential conflicts with people were widespread and often near highly suitable areas. We identified 69 potential reintroduction sites (10 230km2, 1.8% of the ecoregion) that have suitable summer and winter habitat with relatively low risk of human-wildlife conflict. These results can guide conservation efforts in establishing a viable European bison metapopulation in the Caucasus ecoregion. More broadly, our results highlight the need to map large mammal habitat suitability for different seasons in order to derive meaningful conservation recommendations. © 2015 Elsevier B.V.


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).


Akatov V.V.,Maikop State Technological University | Akatova T.V.,Caucasian State Biosphere Reserve | Shadzhe A.E.,Maikop State Technological University
Russian Journal of Ecology | Year: 2012

The consequences of replacement of native dominants by alien species (Ailanthus altissima, Ficus carica, Robinia pseudoacacia, Acer negundo, and Amorpha fruticosa) in the tree and shrub layers have been studied in riparian forests of the Western Caucasus. The results show that the invasive dominant species do not always achieve higher abundance, compared with native dominants. When this is the case, however, the dominance of alien species as stronger competitors leads to reduction in the species richness of communities, because they not only intercept the greater part of resources from the environment but also provoke increasingly strict partitioning of remaining resources among associated species. © 2012 Pleiades Publishing, Ltd.


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.

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