Biologia 72/2: 184—193, 2017 Section Zoology DOI: 10.1515/biolog-2017-0021 Harvestmen (Opiliones) communities in an arboretum: Inﬂuence of tree species Slavomír Stašiov 1 , Eva Michalková 1 , Ivan Lukáčik 2 & Marek Čiliak 3 1 Department of Biology and General Ecology, Faculty of Ecology and Environmental Sciences, Technical University in Zvolen, T. G. Masaryka 24, SK-96053 Zvolen, Slovakia; e-mail: stasiov@tuzvo.sk 2 Borová hora arboretum, Technical University in Zvolen, Borovianská cesta 66, SK-96053 Zvolen, Slovakia, e-mail: lukacik@tuzvo.sk 3 Department of Applied Ecology, Faculty of Ecology and Environmental Sciences, Technical University in Zvolen, T. G. Masaryka 24, SK-96053 Zvolen, Slovakia; e-mail: marek.ciliak@tuzvo.sk Abstract: 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. Key words: arboretum; harvestmen; Opiliones; tree species Introduction Harvestmen are terrestrial arachnids. They live mainly on the soil surface, but occasionally can occur in deeper layers of the soil, on walls and the inside of buildings. Harvestmen have several functions in the ecosystems. These arachnids are known as polyphagous organisms, but prefer animal food. They prey on various inverte- brates in diﬀerent growth stages. This way, harvestmen participate in the maintenance of the natural equilib- rium in a wide range of habitats. The other food sources for harvestmen are dead invertebrates and other organic remains. Harvestmen thus contribute to the material cycle and energy ﬂow in nature (Pinto-da-Rocha et al. 2007). Temperature and humidity of soil are considered the main abiotic factors inﬂuencing the structure of har- vestmen communities (Almeida-Neto et al. 2006; Pinto- da-Rocha et al. 2007). However, in forest habitats the distribution of harvestmen is markedly inﬂuenced, be- sides other factors, also by tree species because they af- fect microclimatic conditions. Only little attention has been paid to the study of tree species inﬂuence on the species structure of harvestmen communities (Proud et al. 2011; Merino-Sáinz & Anadón 2015). Although some works include data on species composition of harvest- men communities in diﬀerent forest stands, they are rather faunistic and do not deal with the comparison of harvestmen communities among studied forest stands (Maršalek 1999, 2004; Maršalek & Stašiov 2015; Mihál 2005; Mihál & Mašán 2006; Stašiov 2000; Stašiov et al. 2003, 2010). The aim of our research is to specify the inﬂuence of tree species and related attributes of soil and leaf litter (pH, conductivity, content of H, C, N and P) on harvestmen communities. The Borová hora arboretum is especially suitable for this purpose due to the pos- sibility to assess the diﬀerent ecological properties of various tree species in a single homogenous area. Material and methods Study sites The Borová hora arboretum is an important educational and research facility, belonging to the Technical Univer- sity in Zvolen. The planting of trees started here in 1965 c 2017 Institute of Zoology, Slovak Academy of Sciences Brought to you by | UCL - University College London Authenticated Download Date | 3/29/17 10:51 AM