Tree-modified soil properties influence the structure of harvestman (Opiliones) communities

Abstract Although harvestmen are a relatively well-studied group of arachnids in Europe from a faunistic point of view, detailed information about the ecological requirements of individual species is still lacking. Several species are closely associated with the humid environment facilitated by vegetation. In forests, habitat features (including leaf litter and soil properties) are predominantly driven by tree species distribution and characteristics, but their specific effects on harvestman community composition are not well understood. Therefore, our study examines selected characteristics of vegetation and soil and litter properties under monocultures of autochthonous and allochthonous tree species and their effect on harvestman community. Research was carried out in the Mlyňany Arboretum (western Slovakia), in nine monoculture stands of autochthonous and allochthonous tree species. Harvestmen were collected by pitfall trapping during vegetated periods in 2013–2015. In total, 429 individuals of 11 species were obtained. The general linear models revealed the litter C/N ratio as a significant predictor of harvestman diversity. Both species richness and Shannon diversity decreased with an increasing C/N ratio. Variation in harvestman community composition was significantly related to the C content in the litter ( p = 0.022). The majority of the species preferred habitats with more palatable litter with a lower C/N ratio and C content. In terms of both overall epigeic activity and species richness, forest stands of autochthonous tree species provided more suitable conditions for harvestman communities than forest stands of allochthonous tree species. Our results provide new knowledge about the environmental variables helping form the habitat associations of harvestmen in forest stands.