Abstract: Population,community composition and trophic groups of soil nematodes in soils contaminated with arsenic(As) at three levels were studied.A total of 27 genera of nematodes were observed and dominated with Aphelenchoides in all the soils.Bacterivorous and fungivorous nematodes were dominant groups in soils,low and medium in As level,respectively,whereas,plant-parasites were the predominant group in soil,high in As level.Wasilewska index(I_W) and maturity index(I_M) of nematodes living freely in soils low and medium in As level were much higher than in soils high in As level,while the plant-parasites index(I_PP) and I_PP/I_M exhibited an opposite trend.The findings indicate that in soils high in As contamination level,the soil food web was heavily disturbed,and its soil environment quality for the community was much poorer than in soils low and medium in As level.It is,hence,suggested that structure of the nematode community is a potential indicator of changes in soil quality and ecosystem.

Key words: soil nematode, arsenic, ecology index, soil quality