Putting provenance into perspective: the relative importance of restoration site conditions over seed sourcing

Post-mining scenarios present challenges for restoration in a wide range of environments, especially in the context of climate change. The source of seed for restoration has been an issue of intense focus, as seed provenance can impact plant fitness and restoration outcomes. However, post-mining landscapes require substrate reconstruction prior to vegetation re-establishment. Critically, the relative importance of provenance and substrate in ecosystem recovery has been rarely quantified in a statistically rigorous framework. We established a large provenance trial with Banksia attenuata and Eucalyptus todtiana at two Western Australian mine sites in post-mining reconstructed and adjoining un-mined substrates. We show that site and substrate were 4 and 26 times more important than provenance in explaining survival for B. attenuata and E. todtiana, respectively. At one site, there was 100% mortality in the post-mining substrate but high survival and no clear provenance effect in the un-mined substrate. At the second site, there was again no clear provenance effect, but E. todtiana survival was higher in the post-mining than un-mined substrate. Our results show that post-mining substrate changes can overwhelm provenance issues. Consequently, where substrates are highly impacted, alternative restoration targets and/or greater investment in substrate research are needed to improve restoration outcomes. Due to the thousands of mines across the world, this is an internationally relevant finding with important implications for investment into global ecosystem recovery.