In this synchronic study, soil nematodes communities were used as indicators for understanding the processes of fallow succession in the semi-arid zone of West Africa (Senegal). Characteristics of nematode communities were described by mean of indexes : abundance of plant parasitic, fungal feeding and bacterial feeding nematodes (trophic structure), specific richness and evenness (species organization) of root feeder group. Changes in trophic structure and species organization globally showed continuous trends from young fallows to mature stage of the succession that support theoretical successional progresses. Indeed, growth in abundance of plant parasitic, fungal feeding and bacterial feeding nematodes respectively indicated (i) increase in primary production related to natural vegetation regeneration, (ii) develoment of soil microorganisms following on reconstitution and (iii) accumulation of organic matter. Increase in evenness and number of species indicated (i) the establishment of a network of biotic interactions that contribute to more efficient resource use and (ii) progressive functional resistance of ecosystem according to the "redundant species" hypothesis. In addition, soil nematode parameters were sensible and expressed interactions of various factors uncontrolled, such as particular environmental conditions, typical of field conditions, or previous management regimes, with successional processes. Finally, during the three years of the survey, the structure of nematode communities, described by indexes analysis, showed little temporal changes and supported the use of nematodes as stable indicators. These practical attributes strengthen the convenience of soil nematodes for assessing the ecosystem state and understanding its functioning, particularly as framework for managing soil fertility in the purpose of sustainable improve of productivity in tropical agrosystems.