The spring aspect of the herpetobiontic spider assemblages (Araneae) of some biocenoses forming the row meadow - birch forets of Mordovia

There were examined the assemblages of herpetobion spiders from five habitats in the vicinity of the village of Ekaterinovka (Lyambirskiy District, Mordovia, 54°09'N, 45°33'E) in May 2008 using pitfall-traps. The habitats differed in the degree of development of the tree stratum and formed a series from the grassland to the mature birch forest. The spider populations of the grassland and grassland-birch thicket ecotone differ from that of birch forests in species composition, total occurrence rate (ind./100 trap-days) and composition of the dominant species. The number of spider species increases, the indices of ecological diversity and evenness (equitability) decrease in the succession series we studied. In the spring spider assemblages in the grassland the most abundant species is Pardosa palustris, in the ecotone - Pardosa paludicola, and on forests - Pardosa lugubris.