Doudle, S./ W. Williams/ V. Galea 2011: Improving rehabilitation outcomes using biocrusts. - 8th International Heavy Minerals Conference 2011 : 85-97. [RLL List # 231 / Rec.# 34646] Keywords: Atmospheric nitrogen/ Ecological process/ Field scale/ Fresh Water/ Functional components/ Heavy minerals/ Irrigation waters/ Laboratory experiments/ Mine rehabilitation/ Rapid regeneration/ Rehabilitation outcomes/ Salinity levels/ Semi arid/ Soil cover/ Soil disturbances/ Soil particles/ Soil surfaces/ South Africa/ South Australia/ Surface coverages/ Upscaling/ Arid regions/ Ecology/ Fungi/ Human rehabilitation engineering/ Irrigation/ Minerals/ Reforestation/ Surfaces/ Water quality/ Water supply/ Soils/ Ecology/ Fungi/ Human Engineering/ Irrigation/ Minerals/ Reforestation/ Soil/ Surfaces/ Water Quality/ Water Supply
Abstract: The Iluka Resources Ltd Jacinth-Ambrosia heavy mineral sand mine (South Australia) is located in an undisturbed semi-arid landscape consisting of sparse trees, shrubs and grasses. The soil interspaces are covered with biocrusts, a living soil cover also found worldwide in arid regions. Biocrusts are composed of lichens, cyanobacteria, algae, mosses, liverworts, fungi and bacteria, and live on and within the first few millimetres of the soil surface. Biocrust organisms bind soil particles, sequester carbon and many fix atmospheric nitrogen making them important structural and functional components of ecosystems. Despite their important role in ecological processes, biocrusts are susceptible to disturbance; nevertheless they can recover provided sufficient inoculum is present. Cyanobacteria are the early colonisers and they capture atmospheric and landscape resources and establish conditions that subsequent successional seres can capitalise on. Research conducted in countries including China, Spain and South Africa has been focused on methods to either encourage rapid regeneration of cyanobacterial remnants or to introduce new material from cultured cyanobacteria. We have been investigating the extent and diversity of biocrusts across the 4500 ha mine lease and their potential to improve mining rehabilitation outcomes. Approximately 46 per cent of the soil surfaces are colonised with biocrusts and 33 taxa have been identified. Laboratory experiments were designed to mimic massive soil disturbance and treated with a range of water qualities. Within 22 days, treatments irrigated with fresh water were colonised by new cyanobacterial filaments with a mean surface coverage of 65 per cent. Secondary tests revealed that differences in the photosynthetic yield of the crust were dependent on the salinity levels of the irrigation water used. In 2011 this program is expanding from the laboratory into field scale trials designed to assess both the potential and practicalities of up scaling these techniques to provide crushed biocrusts and cyanobacterial bio-inoculum for use in mine rehabilitation.