Ants as indicators of minesite restoration: community recovery at one of eight rehabilitation sites in central Queensland

Abstract

Summary Ants have been widely used as bioindicators of the success of minesite restoration throughout northern Australia. Our study describes ant species richness, species composition and functional group composition at eight sites undergoing rehabilitation (2–10 years old) at Callide Mine near Biloela, Queensland (680 mm mean annual rainfall) and compares them with those at three nearby, unmined reference sites. We address the extent to which ant communities at rehabilitation sites have converged with those at reference sites and, while we found convergence occurred at only one of the eight sites, we consider this highly noteworthy as it is the only case we are aware of where a rehabilitation minesite has achieved such convergence. Ants were sampled using pitfall traps (15 per site) during January 2001, the period of maximum ant activity. A total of 146 ant species from 34 genera were recorded. Species richness ranged from 36 to 48 (mean of 41) at reference sites, and from seven to 49 at rehabilitation sites (mean of 26). Species richness at rehabilitation sites increased systematically with rehabilitation age. Despite rapid colonization by ants, in most cases, ant communities at rehabilitation sites were markedly different from those at reference sites. However, one rehabilitation site (TH91) was an exception: it had the highest species richness of any site, it grouped with reference sites in multivariate analysis, it supported ‘reference’ rather than ‘rehabilitation’ species, and it supported a full range of functional groups. Ground‐layer conditions at TH91 were similar to those at reference sites and local, long‐lived woody plants had successfully established. We believe these are key factors leading to successful ant community restoration.