Does Gamasid mites (Acari, Mesostigmata) observed in oil palm and rubber plantations can be used as indicators of tropical secondary forest soil transformation?

Abstract

The aim of the study was to assess modifications in the community of soil mesostigmatid mites’, as indicator of environment stability with land-use change across 2–4 texturally distinct soils in La Mé and Grand Lahou, Côte d’Ivoire. The fieldwork was carried out in humid period on two study sites: 1– rubber landscape (secondary forest, 7-, 12- and 25-year-old rubber plantations) and 2– oil palm landscape (secondary forest, 13-, 20- and 39-year-old oil palm plantations). Three sampling stands were established in each land-use type and age class, for a total of 24 sampling stands. On each sampling stands, soil cores for Gamasid mite’s extraction were taken at 10 cm soil depth through a 40–50 m transect. Our findings highlighted a drop of mesostigmatid mites’ density (–49% and –52%), species richness (–41% and –40%), and diversity (–35% and –49%), respectively after conversion of the secondary forests into rubber and oil palm plantations. The soil with clayey sandy and clayey textures favored the development of the mesostigmatid mites, particularly in the abundance and species richness of Uropodina. However, the soil with sandy clayey textures improved the abundance and species richness of Gamasina. The mesostigmatid mites’ community was degraded in sandy-textured soils. In light of the Maturity Index values, a better quality of soil and environment was detected in the secondary forests compared to plantations. The results also suggest that the mesostigmatid mites’ community influence the soil nutrients and probably plant productivity indirectly by influencing the populations of their prey.