The Structure of a Soil Nematode Community in Dry Steppe Phytocenoses of Vodnyi Island (State Biosphere Reserve Rostovskii) during the Spring Period

This paper presents the results of study of the structure of a soil nematode community from key sites (index plots) on Vodnyi Island of the State Biosphere Reserve Rostovskii in the spring. A total of 76 genera from 41 families and nine orders were identified with 39 species common for 2 months (April–May). A number of characteristics of soil nematode fauna in spring were shown to manifest themselves in the genus diversity, occurrence frequency, and dominance of particular ecological–trophic groups and genera. The total number of species on index plots varied between 17 and 33; with the number of nematodes ranging from 230 to 994 individuals per 100 cm³ of soil in April and from 134 to 1043 individuals per 100 cm³ of soil in May. The order Dorylaimida, which included 29 genera, proved to be the most diverse by the genus composition followed by Tylenchida with 19 and Rhabditida with 11 genera. An increase in the number of nematodes from phytotrophic group in the spring was directly related to an increase in the fresh aboveground phytomass, as confirmed by correlation analysis (the coefficient of correlation has very high values: r_April = 0.86, r_May = 0.96 at p-level < 0.05).