Harvestmen (Opiliones) communities in an arboretum: Influence of tree species

Although harvestmen (Opiliones) are among the best studied groups of arachnids in Europe from the faunistic point of view, there is still lack of available information on ecological requirements of the particular species. Habitat preferences that determine the distribution of species are largely determined by the habitat structure and microclimate. Besides other factors, these characteristics of habitats are also influenced by the nature of the vegetation. Therefore, our study dealt with the influence of tree species on harvestmen communities. We conducted the research on nine sites in the Borová hora arboretum (Zvolen town, Central Slovakia). Each studied site represents a monoculture of one of nine tree species. On each site also some attributes of soil and leaf litter (pH, conductivity, content of H, C, N and P) were evaluated. Harvestmen were collected by pitfall trapping during vegetation periods in 2008–2012. In total, 2515 individuals of 17 species and 3 families were obtained. Significant differences were revealed between the compared forest stands in terms of total epigeic activity and species richness of harvestmen. The hierarchical cluster analysis divided harvestmen communities into two main clusters (except community of the site with European hornbeam). The first one represented four sites with relatively lower canopy (< 50%) and with the higher number of captured individuals, the second cluster grouped four sites with higher canopy (> 50%) and with the lower number of captured individuals. The results of research confirmed statistically significant relationships between the litter conductivity and equitability and between the litter pH and equitability of harvestmen communities.