Epigaeic invertebrate diversity of post‐mining revegetation evaluated by comparison with adjacent remnant woodlands

Abstract

This study evaluated the validity of invertebrate diversity for evaluating the condition of minesite rehabilitation. Because the aim of rehabilitation of mined lands in this region is to establish a self‐sustaining ecosystem that resembles “bushland,” a variety of remnant woodlands in the vicinity of the minesite were selected as reference sites. Reference sites encompassed a range of soil types (alluvial, coarse‐textured, or clay) and understorey structural types (grassy, grass, and shrub or shrubby). Grassland sites (cleared woodlands) were also sampled to provide a negative control. Epigaeic invertebrates of three rehabilitation sites were compared with five reference sites and three grassland sites using pitfall traps over 6 years. Sites were sampled annually and the annual data within each of two time periods (T1: 2008–2010 and T2: 2011–2013) were pooled. Ants, beetles, and springtails were identified as morphospecies, providing site species richness and composition data. Springtail metrics of all three habitats, reference, rehabilitation, and grassland, resembled each other in T1 as well as T2, indicating that rehabilitation rapidly provided suitable conditions for this group. In contrast, the ant and beetle composition of rehabilitation sites differed significantly from that of reference sites in T1 but not T2, although only ants matched the expected negative control with grassland sites remaining distinct from reference sites in both time periods. Thus, ant assemblages of rehabilitation sites show a positive trajectory toward native woodlands and away from grasslands. These findings demonstrate that rehabilitation sites are developing diverse invertebrate assemblages comparable to local remnant woodlands in relatively short time frames.