Identification of potential invertebrate bioindicators of restoration trajectory at a quarry site in Hunua, Auckland, New Zealand.
In 2009, the New Zealand company Winstone Aggregates initiated a restoration planting scheme to mitigate the ecological damage caused by mining at the Hunua Quarry, near Papakura, New Zealand. By employing several collection methods (pitfall traps, artificial cover objects, litter samples, weta motels), and comparing invertebrates found in the restoration area with those found in adjacent areas of mature forest and unplanted grassland, this study aimed to identify invertebrates that could be used as bioindicators of restoration trajectory. Multivariate analyses (NMDS, ANOSIM) indicated that the composition of some invertebrate assemblages (e.g. beetles, mites, springtails) may be used to determine whether assemblages in the restoration areas had converged towards those in the mature forest. The survey also identified specific taxa (e.g. cave weta, spiders) that were more abundant in, or exclusive to, the mature forest, and identified other groups (e.g. exotic earthworms, slugs, snails) that typified the grassland invertebrates. Thus, in future invertebrate assessments, an abundance of the former taxa, and lack of the latter, would provide an indication of restoration 'success', and assist in monitoring the trajectory of the invertebrate community from that found in the exotic grassland towards an assemblage more typical of the native forest habitat of this region.