Inventory completion and complementarity of ant assemblages in a variety of habitats and a suite of sampling methods

Abstract

Comparative studies have found that, when different sampling methods are used in the same habitat, each of them will contain a few unique species that are not represented in any other sampling method. The efficiency of methods will also vary between habitats. This study made a comparative evaluation of methods used to collect data for estimating ant diversity.in particular, the study aimed to evaluate the efficiency of pitfall traps at estimating ant richness and assemblage structure in varied habitats. The study was conducted in the southern aspect of the Soutpansberg Mountain and it included forest and woodland habitats. A total of 4970 ants (61 species), 6 subfamilies and 27 genera were collected in the four habitats. Overall there was no significant difference between sites (R = 0.057, p = 0.27) accept for a pair-wise comparisons between close woodland and Gallery forest (R= 0.15, P= 0.03). Pitfall species richness predicted 94% of the total site species richness (R2 0.94). Baiting was the worst predictor of species richness (R2 =0.02). Active search predicted (R2 = 0.29) of the total species richness and Winkler extraction predicted (R2 =0.35) of the total species richness.Winkler extraction had the highest inventory completion (93%), followed by Bait (91%), Pitfall traps (89%) then active search with the lowest (85%).Overall there was no significant difference between Habitats (R = 0.057, p = 0.27)accept for a pair-wise comparisons between close woodland and Gallery forest (R= 0.15, P= 0.03 There was a resemblance in species caught in closed woodland and species caught in the gallery forest, points were closer to each other. There was a significant difference between methods (R = 0.374, p = 0.01*) except for the comparison between active searching and Winkler which showed low significance (R= 0.07, P = 0.8). The MDS of methods suggest that pitfall trapping clearly caught a different set of ant assemblages, which was also true for baiting, but to a lesser extent. Although pitfall trapping was not exhaustive in terms of species caught it is a viable surrogate for comparative studies of species richness and assemblage structure for ants in these varied habitats.