Identifying and ameliorating nutrient limitations to reconstructing a forest ecosystem on mined land

Nutrient deficiency is commonly a limiting factor in reconstructing ecosystems on disturbed areas such as mines, quarries, and construction sites. An open-cut coal mine in southeastern Australia is being used as a model to explore strategies for reconstructing a sustainable forest ecosystem on a spoil substrate. This study aimed to identify the nutrients limiting forest establishment and ways of ameliorating these. A pot trial, using two endemic Myrtaceae tree species, found that nitrogen was the most growth-limiting nutrient followed by phosphorus. To overcome these spoil nutrient deficiencies, a field trial compared the application of forest topsoil to the addition of two rates of inorganic fertilizer, gypsum, or biosolids on the response of a range of native forest plant species directly seeded into the substrate. Only biosolids significantly increased total nitrogen levels in the spoil. However, all treatments significantly decreased spoil pH, thereby increasing nutrient availability. Topsoil produced the highest plant density of native species due to contributions from its seed bank. Biosolids increased growth of <i>Corymbia maculata</i>. The higher rate of fertilizer addition improved seedling establishment of Mimosaceae and the survival of Myrtaceae species. High nutrient treatments increased weed and grass densities, which may have reduced the nutrient benefit for native species. In conclusion, biosolids and the high rate of fertilizer application ameliorated the nitrogen and phosphorus deficiency of spoil to support growth and survival of reintroduced native species. However, potential benefits were attenuated by competition from accompanying weed growth that could be managed by implementing a control program