Soil free-living nematodes as indicators of both industrial pollution and livestock activity in Central Asia

The effect of industrial pollution on soil free-living nematode communities, trophic groups, and taxon composition was investigated along an 18-km transect that included the Angren power plant, a gold-refinery plant, farm areas, and recreation areas. Soil samples were collected in May 2005 and October 2006 from the upper (0-10 and 10-20 cm) soil layers in downwind directions from the industrial complex emission sources of the Angren industrial sites. Direct and indirect (through soil property changes), separate and integrated effects of industrial pollution and livestock activity on the soil nematode community were found. The total number of nematodes was found to be negatively correlated with the amounts of chemical elements in soil and positively correlated with the calcium concentration in soil. The nematode communities, trophic diversity, and taxon composition were found to be affected by the variety and concentration of chemical elements. The widely used ecological indices applied in the present research were sensitive to environmental disturbances caused by industrial pollution as well as livestock activity. The Wasilewska index, nematode channel ratio, and maturity index were mostly affected by trace metal concentration, while the diversity indices and species richness were mostly affected by soil property changes. The nematode channel ratio indicated that the bacterial-based decomposition process was dominant in soils exposed to both strong industrial pollution and livestock activity. The diversity indices indicated the disappearance of rare species in the industrial area and an increase of the contribution of common nematodes with increasing depth and distance from the unfavorable area. The current study confirmed that the grazing in accompaniment to industrial pollution, intensify a negative effect on soil nematode communities.