Vertical distribution of edaphic oribatid mites (Acari: Oribatida) in two artificial forests planted on temperate grasslands

Abstract

Context. Oribatid mites are the most abundant taxon in forest soilsthat rely on porosity and organicmatter availability. Exotic forests of Pinus radiata and Eucalyptus globulus planted over nativegrasslands in the Pampas region of Argentina have produced modification in soil properties, whichcan affect the composition and structure of native oribatids communities. Aims. To compareoribatid communities in soils under artificial woodlands of pine and eucalyptus and to assess thevertical distribution of oribatids in relation to edaphic variables. Methods. In each forest, oribatidswere collected from three levels of the A horizon: (1) litter layer; (2) 0–5 cm; and (3) 5–10 cm. Edaphicvariables measured were penetration resistance, bulk density, total porosity, pH and water contentand luminosity at soil level. Density, species richness, diversity and evenness of oribatids werecalculated in each level of each forest. Comparisons were made through multivariate analyses.Key results. Edaphic variables showed no significant differences between plots but litters werestructurally different. Richness and diversity showed no differences between plots whereas evennesswas significantly higher in plot P. Density had higher values in the litter layer of both forests. CanonicalAnalysis of Principal Coordinates(CAP)showed that Pine plots had a more defined vertical distribution.Conclusions. The structure and composition of litters promoted differences in the verticaldistribution of oribatids. In Pinus, thick unaltered litter showed a marked vertical gradient of mitesalong levels while in Eucalyptus, thin and easily decomposing litter, showed no vertical patterns.Implications. Assessment and management of soil biodiversity in artificial woodlands.