Arboreal ant diversity (Hymenoptera: Formicidae) in a central African forest

Like many developing tropical areas, central Africa is subject to substantial anthropogenic disturbance associated with the large-scale harvesting of natural resources. We surveyed the ants of the forest canopy at an oil extraction site near Gamba, Gabon. Ants were collected by hand and with tuna baits from nine tree crowns in late secondary forest. Thirty-six ant species were collected in all. Michaelis-Menten and incidence-based richness coverage estimates indicate that this represents 65% of the arboreal ant species richness at the site. Crematogaster spp. generally were behaviourally aggressive and monopolized baits in most trees. Taxonomic similarity (classical Sorensen index) averaged 0.25 (range = 0.00-0.50) between trees and was not a function of the distances separating them. No edge effects were detected, but there was a tendency for trees within the same forest patch to show higher similarity in ant composition than trees in separate patches. Overall arboreal ant species richness and composition in the disturbed forests around Gamba were similar to those found in primary forests of the region.