Successional trends in the characteristics of soil nematode communities incropped and fallow lands in Senegal (Sonkorong)

Soil nematode communities in the 0-15 cm soil layer are used as indicators for describing the processes of fallow succession in the semi-arid zone of West Africa (Senegal). Abundance of plant feeding nematodes, non-plant feed ing nematodes, plant parasite index (PPI), species richness and Shannon eve nness of plant parasitic nematodes were measured at five stages of successi on: fields, early (1-3 years), intermediate (8-10 years), old (18-20 years) fallows, and forest stage. These nematological indexes were analyzed simul taneously by multivariate analysis to show the indicative properties of nem atode communities. Overall, changes in abundance of nematode groups, PPI an d diversity, show continuous trends from early fallow to mature stages of t he succession; these trends parallel theoretical trends in secondary succes sion. In addition, soil nematode parameters were meaningful and expressed i nteractions of various uncontrolled factors with successional processes, su ch as environmental conditions or cropping history. During the 3 years of t he survey, the structure of nematode communities, described by index analys is, showed little temporal change and supported the use of nematodes as sta ble indicators. (C) 2000 Elsevier Science B.V. All rights reserved.