Oribatid mites (Acari, Oribatida) community structure and soil quality along the cashew chronosequence in Côte d'Ivoire

Tropical forests are increasingly converted into agricultural lands, thus causing a serious threat to the stability and resilience of tropical ecosystems. This study was conducted in a successional stage of cashew trees (young, mature and old plantations) and, in forest lands, to evaluate the modification of oribatid community and soil physico-chemical properties through the transformation of forests into plantations, and how these change with the aging of the plantations. Samples were collected in 0-10 cm and 10-20 cm soil depth for oribatid mites' extraction and characterization of the physical properties. Conversely, chemical measurements were made on samples taken in the 0-20 cm soil depth. Results showed that the conversion of forests into plantations leads to an increase in bulk density (+ 15% and + 13%) and a decrease in soil porosity (- 17% and - 15%), organic carbon (- 21% and - 18%), total nitrogen (- 10% and - 20%), available phosphorus (- 6% and - 2%), organic matter (- 21% and - 18%), oribatid density (- 92% and - 70%), species richness (- 84% and - 66%) and Shannon index (- 74% and - 48%), respectively, in the young and old cashew plantations compared to the forests. The oribatid community and soil quality increased with the aging of the plantations, but only the last one reached similar conditions to forest. Conversely, soil porosity, water content, organic carbon and most of soil nutrients were higher in the older plantations and lower in the mature plantations. Options to improve sustainable production and soil biodiversity are discussed.