Ecological Structure of Soil Nematode Communities of Southern Chukotka

Abstract

The soil nematode communities in typical tundra soils of southern Chukotka have been analyzed. Five types of shrub and grass-shrub biotopes on Cryosols, Fluvisols, Histosols, Gleysols, and Cambisols were examined. The animals were extracted from the soil by the Baermann technique with subsequent determination of taxonomic diversity, total and relative abundance, 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 one (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. The 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 Gleysol (18%). The nematode fauna of the soils under analysis differed significantly. The greatest diversity of nematodes was found in the peat horizon of the Fluvisol, and the smallest diversity of nematodes was recorded in the litter of the Cambisol. The values of Sigma Maturity Index ranged between 2 and 3. The Enrichment Index had low and moderate (1.40–41.02) values, and the Structure Index had high values (59.51–84.07). The Eudorylaimus and Plectus genera 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 biocenosis.