Effect of Different Agroecosystem on Earthworm Diversity in Azaguié Locality (Côte d'Ivoire)

Abstract

In most terrestrial ecosystems, earthworms are considered to be excellent bioindicators of biodiversity and soil quality. However, their diversity and abundance encountered depend on the systems considered and on the anthropic pressure exerted. The objective of this study was to assess the impact of a land use on the earthworm community. Earthworms were collected in TSBF (Tropical Soil Biology and Fertility) type monoliths by the direct manual sorting method in three types of farms (fallow, rubber plantation and mangosteen plantation) in the locality of Azaguié. Measurements of the physicochemical parameters of the soil, in particular, the total organic carbon level, the organic matter rate, the nitrogen rate, the conductivity, the hydrogen potential (pH) and the total phosphorus were carried out at the Laboratory Central of Agrochemistry and Ecotoxicology (LCAE) from 200 g of clod of soil sampled in different monoliths. These studies showed that in all the plots analyzed, the endogeic polyhumic worms presented the highest densities while the epigeic detritivorous worms presented the lowest densities. The distribution of earthworms in the mangosteen plot was homogeneous, unlike that of the other plots. However, the physico-chemical parameters of the soils were higher in the fallow. The canonical correspondence analysis carried out to assess the relationship between the variability of the earthworm density of the plots and the physicochemical parameters measured showed that the physicochemical parameters measured explained only a substantial part of this distribution of earthworms while the other part is possibly linked to other environmental factors.