October 2015

A common decision made early in mining is how much soil to salvage for rehabilitation, and where to place it. The success of terrestrial revegetation depends on soil quality. For example, the height and width of manuka and kanuka is halved when planted into Waikato coal mine overburden (fire-clay) with little topsoil. This creates larger gaps between plants, which are prone to to invasion by pampas and gorse, and increases required maintenance and slows forest regeneration. We have found, manuka is more competitive on higher-stress sites. The risk of less tolerant plants dying in summer (from drought) or in spring (from water-logging) is also higher in poor soils. Many mines have a topsoil shortage; so this research is also measuring the effectiveness of ways to improve plant establishment and growth under a soil shortfall.