Zoning Northern Eurasia based on the fauna of terrestrial vertebrates and their classification by similarity of distribution

Abstract

For the purpose of zoning on the basis of fauna of terrestrial vertebrates, Northern Eurasia was considered within the boundaries of the Soviet Union in 1991 and divided into 245 mapping units. Mapping units were marked on the World Vegetation Map at a scale of 1: 20000000 in such a way that each mapping unit occupied a territory within the limits of a natural subzone having a latitudinal distance of 10°. A list of the vertebrate species was generated for each unit. Jaccard similarity coefficients were calculated for the lists; the coefficients were used as the basis for performing the cluster analysis of fauna of the mapping units. Based on the results of calculations, a hierarchical classification has been created. This classification includes 5 faunistic regions (regional groups of subregions), 6 subregions, 18 provinces, and 14 districts. Environmental factors that correlate with faunistic heterogeneity in the studied territory were described. The proposed zoning takes into account 57% of the variance of the similarity coefficients of the faunas of specific regions (coefficient of multiple correlation is 0.75). It is 2–2.5 times more informative than the previously developed schemes on particular groups of animals, which reflected, as the researchers thought at that moment, the heterogeneity of fauna of terrestrial vertebrates in general. Association with environmental factors and natural conditions may explain 82% of the heterogeneity of the fauna (correlation coefficient is 0.91). Comparing the results of zoning that were carried out for different classes of terrestrial vertebrates (amphibians, reptilians, birds, and mammals), we found significant similarity between causes of fauna heterogeneity (zonal features, provinciality, heat availability, and their combined effect). Nevertheless, differences in tolerance to the environment among the studied animal classes resulted in the substantial discordance of the boundaries of the described taxa and their hierarchy. This discordance was found during zoning. A classification of 1243 species of terrestrial vertebrates inhabiting the territory under study is performed based on the similarity of their occurrence (the average in the lower taxon faunistic zoning) and covers three types of distribution: Northern, Middle and Southern. These in turn are divided into 7 subtypes and 13 classes. The informative presentation of the classification is equal to 53% of the variance (correlation coefficient is 0.73).