Nutrient dynamics of dominant Acacia species of the Telfer region in the Great Sandy Desert and their potential in mine-site rehabilitation

[Truncated abstract] Mining is a major activity in the Australian arid region, and mine-site rehabilitation is a fundamental part of the mining operation. Most substrates used in rehabilitation of mine sites are of low soil nutrient availability, but with elevated levels of metals that may be toxic to plants. Nutrients and potentially toxic elements can significantly affect rehabilitation success. Native legume species are always considered for mine-site rehabilitation, because they are often good colonising plants and possess the ability to improve soil nutrient availability through nitrogen fixation and litter cycling. Many Australian Acacia species occur on a range of soil types, and they are important components of rehabilitation ecosystems. This PhD project aimed to study the nutrient dynamics of dominant Acacia species of the Telfer region in the Great Sandy Desert and assess their potential in mine-site rehabilitation (Chapter 1). First, a field study was carried out to determine nitrogen (N) and phosphorus (P) status of four Acacia species, i.e. Acacia stipuligera, A. ancistrocarpa, A. stellaticeps, and A. robeorum, and quantify N- and P-resorption efficiencies and proficiencies of the four species in order to assess the role of resorption in maintaining plant nutrient balance and the contribution of N and P cycling through litterfall to soil nutrient patchiness. The results showed that all plants were more efficient at P resorption than at N resorption, and that nutrient cycling through litterfall resulted in soil nutrient patchiness and formed “islands of fertility” under the canopies of the shrubs (Chapter 2).