The ecosystem services provided by earthworm populations are poorly studied under perennial crop agrosystems in Côte d’Ivoire. The present study, carried out in the Daloa department, aims to identify groups of responses within earthworm populations to changes in edaphic parameters in three types of perennial crops. To this end, earthworm populations and physico-chemical parameters were sampled on three transects per plantation, in nine plantations divided between three facies: cocoa, oil palm and rubber. The stand of the nine plantations was found to be rich in 13 species of earthworms. Six species dominated the stand, of which four, namely Hyperiodrilus africanus, Stuhlmannia zielae, Dichogaster baeri and Gordiodrilus paski showed a preference for crops. Indeed, Hyperiodrilus africanus, Stuhlmannia zielae and Gordiodrilus paski were indicative of sandy soils under palm plantations; the detritivore Dichogaster baeri was associated with cocoa and rubber plantations where the soils are silty-sandy and have a high organic matter content. These results open up new avenues of research on the roles of earthworms in the functioning of soils in cocoa, palm and rubber plantations in the region. For example, it will be investigated whether earthworm populations can be used in the development of a holistic index similar to the general soil quality index to assess soil quality.

In the climate change context, the reduction of forest area under the influence of cacaoculture is a growing problem. In Côte d’Ivoire, mitigating the effects of climate change in cacaoculture requires the introduction and preservation of woody species in plantations, in association to cocoa trees. However, the current intensification of land use is leading to a reduction of the number of trees associated to cocoa trees and the contribution of this woody flora to the mitigation of the effects of climate change is unclear. Our study aimed to assess the carbon storage of the associated woody species and to characterize the determinants of carbon storage. The circumference at 1.30 m above soil and total height of all individuals taller than 2 m in height were measured in 15 squares of 2 400 m2 for the associated woody stand and in 15 sub-squares of 800 m2 for the cocoa stand. The results showed that the carbon storage of the associated woody stand is 5 times higher than that the cocoa stand and recorded for large trees (diameter > 20 cm; height >8 m) such as Antiaris toxicaria, Ricinodendron heudelotii and Persea americana. Also, this high carbon storage is mainly due to the diameter and total height of the tree and not to the number of individuals. The association of large-scale species with cocoa trees could guarantee the resilience of cocoa agroforestry systems with trees.