Comparative Characterization of Small Mammal Communities in Forest-Steppe and Steppe Landscapes of the South of Western and Central Siberia

Abstract

This study analyzes the fauna, population, and distribution patterns of small mammals of forest-steppe and steppe landscapes of the south of Western and Central Siberia for the period between 1998 and 2021 on the basis of literature data and authors' own materials. Most of these studies were local in nature, while our work is characterized by a generalizing and comparative approach. Seven key research sites were analyzed. Four sites are located in the south of Western Siberia: Ishim forest-steppe (Russian Federation, Tyumen Region), Pre-Irtysh Plain (Kazakhstan, Pavlodar Region), North-Kulunda Plain (Russian Federation, Novosibirsk Region) and Prealtai Foothill Plain (Russian Federation, Altai region). Three sites are localized within the south of central Siberia: Central Tuva Basin (Russian Federation, Republic of Tyva), Shirin and Koibal steppes (Russian Federation, Republic of Khakassia), tazheran steppe of Baikal region (Russian Federation, Irkutsk region). A brief description is given for each site, indicating geographical location, biotopes surveyed, timeline of work, and authors. Population counts and captures of small mammals were carried out according to generally accepted zoological methods. Pitfall trap methods as well as snap traps were used in capturing animals. The dominance structure of each community was assessed using a dominance index representing the proportion of species in the community. To characterize community structure, the first five species were identified by abundance. The dominant species were considered to be those whose proportion in the community was 10% or more. The identification of faunistic complexes was based on faunogenetic and landscape-zonal approaches. Determination of the similarity degree between small mammal communities from different areas was carried out using the method of cluster analysis based on qualitative and quantitative indicators of Jaccard and Sorensen-Chekanov coefficients, with subsequent analysis of dendrograms. GIS mapping methods were used to create the map. The species composition of small mammals includes 37 species belonging to three orders: Eulipotyphla, lagomorpha, and rodentia. The highest species diversity was observed in the steppes of Khakassia (24 species), the prealtay and north-kulunda plains (20-23 species), and the Ishim forest steppe (19 species). In more arid regions, such as the Pre-Irtysh Plain, the Tuva Basin, and the Tazheran steppes of the Baikal region, the number of species decreases (14-16 species). The fauna of small mammals of the studied area is a mixture of species typical of steppes and semideserts of Asia, taiga regions of Siberia, and coniferous-broadleaved forests of Europe. Eight faunistic complexes have been recorded throughout the entire study area, three of which occur everywhere (Boreal, Kazakh-European, European). Of these, the Boreal faunal complex is the most diverse, with a proportion of 38-57% at different sites. The Kazakh-European faunistic complex with the highest proportion is represented in Northern Kazakhstan (31%) and the highest participation of species of the European faunistic complex is found in the Ishim forest-steppe (16%) and North-Kulunda plain (15%). The dominant structure of small mammal communities in the south of Western and Central Siberia is characterized as disturbed, with a sharp predominance of one or two species over other dominants. The dominant species at all studied sites include the narrow-headed Vole with a share of 16-43% and the striped field mouse, which is distributed unevenly among the leading species, with a share of 11-47%. More sporadically, as leaders in abundance, the tundra Shrew, southern birch mouse, steppe lemming, common Vole, striped field mouse, and harvest mouse are distributed. Only in central Siberia, the striped hamster was identified as the dominant species (19%), and in western Siberia on the territory of the pre-Irtysh plain the Siberian (striped) desert hamster (10%). The highest level of similarity in species composition was revealed between the small mammal communities of the Tuva Basin and the Tazheran steppes of the Baikal region, located in central Siberia, as well as between the north-kulunda and pre-Irtysh plains, localized in western Siberia. The small mammal community of the steppes of Khakassia is characterized by the least similarity with all other studied sites.