Conservation value of road verges in the semi-arid Karoo, South Africa: ants (Hymenoptera : Formicidae) as bio-indicators

Ground-foraging ants (Hymenoptera: Formicidae) were used to assess the cons ervation value of road verges in a semi-arid region around Prince Albert, W estern Cape Province, South Africa. Ant communities were sampled using pitf all traps on 50 sites along two roads. Four transects were sampled at each site, two in the road verge and two in adjacent rangeland. A total of 43,29 8 individual ants of 34 species were caught, with 31 and 32 species in the road verge and adjacent rangeland respectively, but on average road verges were the more species-rich. Road verges also contained relatively more rare species (i.e. those species that occurred in < 10% of the traps. Ant speci es richness appeared to be influenced by food availability. Although ants a ppeared to be negatively impacted by higher grazing intensities in the rang eland, there was no difference in species richness between fenced and unfen ced road verges. Species in the road verge may benefit directly from road k ills, and indirectly from lower grazing pressure on plants, increased surfa ce run-off and differences in soil surface temperatures. No alien ant speci es were observed or captured at any of the sites.