A ground up approach to revegetation in the arid zone

Abstract

Revegetation of mine sites in the arid zone is inherently challenging because of high costs, poor plant survival in harsh conditions, and difficulties in managing expectations of various stakeholders. A 'top down' approach to site revegetation uses predominantly mid- and upper-storey species and, in South Australia, typically involves planting of tubestock or line seeding and associated activities, such as watering and weeding. In contrast, a 'ground up' approach involves sowing a site with native seeds of colonising plants using a cropping methodology. A comparative analysis of three approaches to revegetation was conducted, these were: 1) a 'top down' approach using tubestock; 2) a 'top down' approach using line seeding; 3) a 'ground up' approach using agricultural spreading machinery (hereafter broadacre seeding) and native colonising species. The performance of each approach was gauged against identified criteria for mine site closure in semi-arid and arid areas. The analysis showed that revegetation with 'top down' tubestock methods was least effective and the 'ground up' broadacre seeding most effective. Specific areas in which the 'ground up' approach outperformed the 'top down' approaches included increasing site stability, plant survivorship, vegetation structure (complexity), system function, decreasing weeds, cost and risk. Four case studies demonstrating the 'ground up' broadacre seeding technique are presented including the revegetation of two capped sites (a power station's ash dam and a waste infill site) and the conversion of two ex-agricultural sites to native vegetation areas. Broadacre seeding with native colonising species provides many benefits to site stability and productivity and is a cost-effective approach to broad-scale revegetation in the arid zone.