Abstract
Observations from six historic placer gold mines in southern New Zealand have shown that soil-free impermeable clay-rich substrates develop evaporative salt encrustations, leading to elevated electrical conductivity (EC>1 mS/cm) and locally elevated pH (7- 10.5). Endemic halophytic plants can tolerate these extreme conditions, and enhance local biodiversity. High EC excludes competing plants. Part of our research project has been a two-year pilot study to physically remove areas of encroaching sediment and weeds to expand the bare substrates and facilitate halophyte colonisation. This approach is a viable option for enhancing biodiversity on mine sites with extreme chemical environments.