The species composition and structure of the heterotrophic flagellates in forest-steppe soils of the Middle Volga River basin

The species composition and patterns governing the changes in the structure of the heterotrophic flagellate communities in the soils of the forest-steppe (the Middle Volga River basin, Penza oblast) were studied as related to the spatial and temporal heterogeneity of the environment. Fifty-three species and forms of heterotrophic flagellates were identified. The most widespread are eurybiontic species: Bodo designis, Paraphysomonas sp., Spumella sp. (found in all the biotopes investigated), Heteromita minima (94%), Phyllomitus apiculatus (88%), Ploeotia obliqua (88%), Heteromita globosa (82%), and Goniomonas truncata (82%). Representatives of the Cercomonas genus predominate in number. According to the species composition, the communities are divided into three groups: xerophytic grass and shrub phytocenoses, mesoxerophytic pine and small-leaved forests, and mesophytic broad-leaved forests. With the increasing humidity of the biotopes, the species composition of the soil heterotrophic flagellates becomes higher, as well as the diversity of the amoeboid flagellates well adapted to existence on the surface of soil particles.