Invertebrates and the restoration of a forest ecosystem: 30 years of research following bauxite mining in Western Australia

Restoration needs to consider more than just soils and plants. The role of terrestrial invertebrates in the restoration of Alcoa's bauxite mines in the Jarrah (Eucalyptus marginata) forest of Western Australia has been the subject of over 20 individual studies. Projects range from arthropods in soil and leaf litter, to the understorey vegetation, and the tree canopy. Moreover, projects span a range of trophic groups, including decomposers (e.g., springtails and termites), predators (e.g., ants and spiders), and herbivores (e.g., true bugs and ants preying on seeds). Elucidation of recolonization trajectories uses both space-for-time substitutions and long-term regular sampling. Importantly, many studies are at species level rather than coarser taxonomic ranks. This paper provides an historical account and an integrated review of this research. The role of ants as seed predators and as indicators of ecosystem health is described. Successional data for other groups, when measured by species richness (ants, spiders, and hemipterans) and composition (ants and spiders), show their reassembly trajectories tracking toward unmined reference areas. Hemipteran species composition tracks the vegetation reassembly trajectory but not toward unmined reference areas. Studies also have revealed optimal sampling methods for surveying invertebrates and their rich biodiversity in southwestern Australia. In restored mine pits burnt to reduce fuel loads, the response of spiders to this additional disturbance was retrogression/alteration of the post-mining trajectory. Finally, attention is drawn to research areas receiving limited scrutiny to date, such as the contribution of terrestrial invertebrates to ecosystem function and taxonomic groups not yet studied.