Seasonal variation in the nematode communities associated with two halophytes in a desert ecosystem

Abstract

Seasonal variation in the soil nematode communities was investigated in a field study at the Avdat Research Farm, Israel. Soil samples from 0-10 cm soil were collected monthly between May 1998 and May 2000, under the canopy of two halophyte shrubs: Hammada scoparia. and Zygophyllum dumosum. Ecological indices such as ratio of fungivores and bacterivores to plant parasites (WI), fungivore to bacterivore ratio (F/B), trophic diversity (TD), Shannon index (W), dominance (X) and richness (SR) were assessed and compared between treatments and between seasons. Twenty nematode families and 26 genera were observed. Acrobeles, Cephalobus, Aphelenchoides and Rhabditidae were found to be the dominant genera/family. Significant differences were found between seasons (P<0.01) in the number of total nematodes, the four trophic groups and the indices, WI, T, H', lambda, and SR. Bacterivores were found to be the most abundant trophic group in four seasons, their mean relative abundance was 60.6 % of the nematode community. Among ecological indices tested, F/B and lambda were effective in distinguishing differences in nematode community structure between treatments during the study period.