Improving Rehabilitation Outcomes using Biocrusts

摘要

The Iluka Resources Ltd Jacinth-Ambrosia heavy mineral sand mine (South Australia) is locatedrnin an undisturbed semi-arid landscape consisting of sparse trees, shrubs and grasses. The soilrninterspaces are covered with biocrusts, a living soil cover also found worldwide in arid regions.rnBiocrusts are composed of lichens, cyanobacteria, algae, mosses, liverworts, fungi and bacteria,rnand live on and within the fi rst few millimetres of the soil surface. Biocrust organisms bind soilrnparticles, sequester carbon and many fi x atmospheric nitrogen making them important structuralrnand functional components of ecosystems. Despite their important role in ecological processes,rnbiocrusts are susceptible to disturbance; nevertheless they can recover provided suffi cient inoculumrnis present. Cyanobacteria are the early colonisers and they capture atmospheric and landscapernresources and establish conditions that subsequent successional seres can capitalise on. Researchrnconducted in countries including China, Spain and South Africa has been focused on methods torneither encourage rapid regeneration of cyanobacterial remnants or to introduce new material fromrncultured cyanobacteria.rnWe have been investigating the extent and diversity of biocrusts across the 4500 ha mine leasernand their potential to improve mining rehabilitation outcomes. Approximately 46 per cent of thernsoil surfaces are colonised with biocrusts and 33 taxa have been identifi ed. Laboratory experimentsrnwere designed to mimic massive soil disturbance and treated with a range of water qualities. Withinrn22 days, treatments irrigated with fresh water were colonised by new cyanobacterial fi laments with arnmean surface coverage of 65 per cent. Secondary tests revealed that differences in the photosyntheticrnyield of the crust were dependent on the salinity levels of the irrigation water used.rnIn 2011 this program is expanding from the laboratory into fi eld scale trials designed to assessrnboth the potential and practicalities of up scaling these techniques to provide crushed biocrusts andrncyanobacterial bio-inoculum for use in mine rehabilitation.