Ecological Structure of Soil Nematode Communities of Southern Chukotka

The paper analyses the soil nematode communities of typical tundra of southern Chukotka. We have examined five types of shrub and grass-shrub biotopes formed on the Cryosol, Fluvisol, Histosol, Gleysol and Cambisol. The animals were extracted from the soil by the Baermann technique with subsequent determination of taxonomic diversity, total and relative numbers, and trophic groups. The highest number (7044 individuals/100 g of soil) and biomass (12.15 mg) of nematodes were found in the histosol, and the minimum number (1000 individuals/100 g of soil; 1.96 mg) of nematodes in the Cryosol. Bacterivorous nematodes dominated in all soil types. The maximum percentage of bacterivorous nematodes (94%) were found in the Cambisol. Their percentages of fungivorous nematodes in the studied soils ranged from 1 to 42%. Predatory and omnivorous nematodes were present in all soils except for the litter of the Cambisol. Their percentage ranged from 2 to 32%. Phytonematodes were few, their highest number was found in the Gleisol (18%). The nematode fauna of the soils under analysis differed significantly. The greatest diversity of nematodes was found in the turf horizon of the Fluvisol, and the smallest diversity of nematodes was in the litter of the Cambisol. The values of Sigma Maturity Index ranged between 2 and 3. The Enrichment Index had low and middle (1.40–41.02) values, and the Structure Index had high values (59.51–84.07). The genera of Eudorylaimus and Plectus were eudominants in all soil types. The soil food webs formed in the biocenoses under consideration can be characterized as stable and structured except for the alder biocenose.