The workshop comprised visits to active rehabilitation sites, where project coordinators described the rehabilitation measures undertaken and the associated successes and failures. Two of the rehabilitation sites, a Tuart forest site in Wonnerup and a wetland site in Gwindinup, showcased Cristal Mining’s mineral sand mine rehabilitation. The work at the latter site received a Revegetation Industry Association of Western Australia (RIAWA) award last year.
Some key points for effective rehabilitation:
- Grazing control – Grazing by rabbits and kangaroos is a critical issue and tree guards (even the hardier core flute ones) are not very effective. Fencing is expensive but is considered as likely to pay for itself in reduced infill planting/seeding costs.
- Site preparation – The post-mining soil profile must be right and deep ripping to create mounds/furrows and minimise compaction (after the return of topsoil) is important. Poor site preparation compromises revegetation and is very costly to fix afterwards.
- Weed control – Getting on top of weeds prior to revegetation could take a couple of years.
- Seeding/Planting – Many sites in the South West rely on the planting of seedlings. Seeding can be highly effective but is only viable where weed cover is very low.
- Trial different methods – It may take some time and trial & error to work out the best revegetation methods for a particular site. Incorporating a few different methods may help to avoid a complete failure, and trialling of new techniques will assist in finding solutions for the tougher spots. e.g. Cristal Mining trialled growing ‘super’ seedlings with extra long roots (see photo). The technique was originally developed for arid sites with dry soil and unreliable rainfall but has also been found effective in reducing tree seedling mortality in the Tuart forest.
MBS Environmental is highly experienced in rehabilitation planning, coordination and monitoring, and has a selection of specialist sub-consultants to draw upon as required. Please do not hesitate to contact us if we can assist you.