Transformation of rainforest into monoculture plantations alters the density, species richness and community composition of oribatid mites and selects for a higher dominance of parthenogenetic species

The transformation of rainforests into oil palm and rubber plantations poses a major threat to tropical biodiversity. This has been well documented for a number of above- and belowground taxa; however, to what extent this applies to oribatid mites is little studied. Oribatid mites (Oribatida, Acari) are ubiquitous, abundant and diverse soil invertebrates, sensitively responding to land-use changes. Here, we examined alterations in density, species richness, community composition and life history strategy of oribatid mites following the transformation of tropical lowland rainforests into oil palm and rubber plantations in Jambi province, Sumatra, a region heavily affected by deforestation in Indonesia. Oribatid mites were sampled from litter and soil of four different land-use systems: rainforest, rubber agroforest (‘jungle rubber’), rubber and oil palm monoculture plantations. Oribatid mites in the litter layer more sensitively responded to changes in land use than those in soil, with density and species richness in rubber and oil palm plantations being significantly lower than those in rainforest. Community composition in rainforest and juggle rubber was similar, and distinct from that in rubber and oil palm plantations. In monoculture plantations, life history strategy of oribatid mites shifted towards parthenogenetic reproduction with larger genital plate, while sex ratio, egg number per female and body size were little affected. Soil pH and water content were identified as main drivers of community composition in both litter and soil, while soil microbial biomass correlated only with oribatid mite community composition in litter. Our results stress the critical role of plant litter in supporting oribatid mite communities in the face of land-use change. The similar community structure, life history strategies and environmental characteristics in rainforest and jungle rubber point to agroforestry as a promising management option to safeguard soil biodiversity in plantation systems.