Surface-active spiders (Araneae) in ley and field margins

Summary

Surface-active spiders were sampled from a ley and two adjacent field margins on a dairy farm in western Norway, using pitfall traps from April to June 2001. Altogether, 1153 specimens, representing 33 species, were found. In total, 10 species were found in the ley, 16 species in the edge of the ley, 22 species in the field margin “ley/forest” and 16 species in the field margin “ley/stream”.
Erigone atra, Bathyphantes gracilis, Savignia frontata and Collinsia inerrans were the most abundant species in the ley. C. inerrans was not found in the field margins. This species is previously recorded only a few times in Norway. Diplocephalus latifrons, Tapinocyba insecta, Dicymbium tibiale, Bathyphantes nigrinus and Diplostyla concolor were most abundant in the field margin “ley/forest”. D. latifrons, D. tibiale and Pardosa mentata were most abundant in the field margin “ley/stream”, followed by E. atra and B. gracilis. The present results were compared to results from ley and pasture on another farm in the region, recorded in 2000. A Detrended Correspondence Analyses (DCA) of the data sets showed that the spider fauna from the leys were more similar, independent of location, than the fauna in ley and field margins on the same locality. The interactions between cultivated fields and field margins according to spider species composition, dominance pattern and habitat preferences are discussed.