Commercial pistachio orchards in south Africa maintain a lowerdensity and diversity of epigeic spiders (Arachnida: Araneae)

Epigeic spider (Araneae) populations were studied in three commercial pistachio orchards (REM, GVN 1, GVN 19) and in a natural undisturbed Nama Karoo grassland site in the Prieska district of the Northern Cape Province, South Africa.A total of 2814 spiders was collected, representing 25 families and 80 species.The grassland site supported a significantly greater abundance and diversity of spiders (n = 1112, 56 spp.) than the three pistachio orchards, viz. REM (n = 704, 35 spp.), GVN 1 (n = 560, 26 spp.) and GVN 19 (n = 428, 25 spp.). Five families (Agelenidae, Ammoxenidae, Cyrtaucheniidae, Gnaphosidae and Philodromidae) dominated the epigeic fauna of the grassland, whereas the orchard stands were dominated by Linyphiidae, Lycosidae and Salticidae.Overall, species composition was more even in the grassland than in the orchards.