Does post-mining rehabilitation restore habitat equivalent to that removed by mining? A case study from the monsoonal tropics of northern Australia

Context Rehabilitation is increasingly being promoted as a strategy for minimising and even reversing biodiversity loss. Many rehabilitation strategies that aim to provide habitat focus entirely on establishing vegetation. Successful vegetation establishment, however, does not necessarily provide habitat that is ecologically equivalent to that removed by vegetation clearing. Quantitative understanding of faunal responses to rehabilitation is required if rehabilitation techniques are to be refined and deliver desired biodiversity outcomes. Aims I aimed to assess the extent to which post-mining rehabilitation restores bird habitat equivalent to that removed in the mining process on the Weipa bauxite plateau. Methods The composition, abundance and richness of bird assemblages were compared between native forest sites and a 23-year chronosequence of post-mining rehabilitation sites. Native forest sites were made up of three Weipa bauxite plateau land units, including the land unit that represents pre-mining native forest, and two land units that are considered to be potential analogues for the post-mining landscape. Key results Bird abundance and bird species richness increased with rehabilitation age. Bird species richness in the two oldest age classes of mine rehabilitation was similar to values obtained from pre-mining native forest and post-mining landscape analogue sites. The composition of bird assemblages, however, was significantly different. Of all the bird species observed, 25% occurred exclusively in native forest sites, 19% occurred exclusively in mine-rehabilitation sites, and the remaining 56% were recorded in both native forest and mine-rehabilitation sites. Site bird-detection rates were significantly related to site vegetation structure, with inter-specific differences in bird response. Conclusions Post-mining rehabilitation at Weipa has partially made up for the loss of habitat caused by clearing for mining. Twenty-three years after rehabilitation commenced, however, a clear residual impact on biodiversity remains, with a third of native forest birds absent from mine rehabilitation, including several native forest specialists. Implications Rehabilitation can partially make up for biodiversity losses caused by the initial loss of habitat. There is no evidence, however, that rehabilitation can achieve ‘no net loss’. Reliance on rehabilitation to achieve conservation outcomes does not address the fact that many fauna species require resources that are found only in mature forest.