The influence of topsoil management on Stradbroke Island sand mine rehabilitation: implications for ecosystem recovery

Topsoil management has been shown to be a key factor in determining restoration success, however, few long-term studies have evaluated the relative effectiveness of different topsoil strategies following mining. This study compared restoration success of three topsoil techniques at rehabilitated sand mine sites on North Stradbroke Island, Queensland, Australia between 2 and 11 years of age. The three soil placement techniques compared were: 1) stockpiled soil; 2) directly returned fresh soil; and 3) double stripping, where the uppermost few centimetres of topsoil is stripped separately to the B horizon and returned in sequence. Restoration success was assessed using a number of soil and vegetation indicators. Topsoil technique was shown to be most influential in the restoration of soil microbial biomass and bulk density. Double-stripping and direct return of topsoil generally yielded improved understory species richness and recruitment from the soil seed bank compared to stockpiling. These differences were strongest between treatments at the youngest site, however, the similarity of stockpiled sites to unmined open forest communities generally increased with time following rehabilitation. Assessment of longerterm restoration outcomes, such as these, enables more appropriate management recommendations to be made to enhance successional progression of rehabilitated dune island communities. Key words: double-stripping, direct return, Stradbroke Island, rutile.