Potential of ants and beetles as indicators of rainforest restoration: characterising pasture and rainforest remnants as reference habitats

摘要

Assessment of habitat restoration requires baseline information on the communities present in both converted and intact forms of the focal ecosystem to enable comparisons with restored sites. Ants and beetles are commonly used in ecological monitoring programmes, as they display assemblage-level responses to habitat change and can be a more direct measure of the recommencement of some ecosystem functions than the presence of more obvious biota such as plants. However, as these taxa differ substantially in ecological traits, their response patterns and utility as potential bioindicators may vary. Using pitfall traps, we compared assemblages of ant and beetle species between two reference habitats, pasture and remnant rainforest in subtropical eastern Australia. The assemblage composition of both groups differed significantly between rainforest and pasture but only beetles showed accompanying differences in species richness and abundance, which were both significantly lower in pasture. We identified ant and beetle species characteristic of either pasture or rainforest remnants, which may be used as bioindicators in future monitoring programmes. These species, however, displayed patchy distributions, suggesting that the use of individual species as bioindicators is likely to be unreliable. These findings support the use of 'composite habitat indices, which combine information from sets of indicator species. Given that patterns of change in species composition were similar between ants and beetles, either is an appropriate focal taxon for future monitoring programmes. Beetles, however, displayed some limitations as no species were indicative of the disturbed pasture habitat. Ants and beetles are likely to respond in different ways to different aspects of habitat change; thus, using both together could strengthen assessments of rainforest degradation or recovery.