Ant assemblages on rehabilitated tropical landfills

Ant assemblages have been used widely throughout the world except in Asia to assess land restoration. In this study, ant assemblages were studied on three rehabilitated landfills (closed for 11–26 years) and a mature woodland as reference in Hong Kong. Grassland and woodland areas on each landfill were examined separately. Ants were sampled by soil extraction, litter extraction and pitfall trapping to maximize capture efficiency. Simple vegetation measurements were also taken. A total of 64 ant species from 33 genera were recorded. Ant species richness in the three landfills was similar (25–30 species), which did not correlate with the age of rehabilitation. A relationship between ant species richness and various vegetation parameters was not observed. Cluster analysis separated the landfill sites from the reference site, and grassland sites from woodland sites. Composition of ants based on functional grouping differed on the grassland and woodland sites, and functional group composition also separated the landfill sites from the reference site. Ant functional groups but not species richness showed a successional pattern with the ecological development of landfills. However, even after more than 25 years of rehabilitation, the ant assemblages on landfills were still very different from that on the reference site.