The Southwest of Western Australia is one of the world’s biodiversity hotspots. In the jarrah forest there are at least 300–400 plant species in vegetation that is typically mined and as many as 163 species per 0.1 ha. Hence, restoring the plant species to post-mining areas is seen as a priority. Approximately 70% of understorey richness is returned via the direct transfer of fresh topsoil. Additions of provenance-correct seeds of between 78 and 113 native jarrah forest species add significantly to post-mining species richness. Many of the broadcast seeds receive a prebroadcast heat or smoke treatment to increase germinability. Approximately 20 additional species are produced by vegetative multiplication or tissue culture and planted into restored areas. Though sequential improvements during the past 30 years, Alcoa now achieves its target to establish in restored areas the same number of native plant species per 80 m2 as the natural forest. Resampling of permanent plots revealed that species composition of older post-mining areas does not become more similar to unmined forest over one to three decades. Few species (mostly orchids) establish after the first year of restoration and adherence to the initial floristic composition model of forest succession applies to jarrah forest mine site restoration in Western Australia. Alcoa’s strategy, therefore, is to maximize the diversity of understorey species in newly restored sites at the first attempt. Future research will investigate methods to further increase the density of the fire resprouter species, a group of species currently under-represented in the restored bauxite mining sites.

Restoring a Jarrah Forest Understorey Vegetation after Bauxite Mining in Western Australia

Is rhizosphere remediation sufficient for sustainable revegetation of mine tailings

The nature and extent of environmental disturbance associated with mining commonly entails completely new and challenging combinations of climate, lithology and landform. Consequently, the outcomes of ecological processes associated with the recovery or restoration of ecosystems cannot be predicted reliably from previously known associations between their physical and biological components. For radically disturbed sites, we propose that it is not practicable to aim for the restoration of historical ecosystems. However, hybrid (reversibly different) or novel (irreversibly different) ecosystems comprising new combinations of physical and biological components, including both native and non-native species, could provide levels of stability and functionality acceptable to all stakeholders and within feasible management regimes. We propose that limiting physical conditions of the landscape can be identified and managed, and that alternative species combinations for introduction to these new landscapes may be considered with cautious optimism.

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Adopting novel ecosystems as suitable rehabilitation alternatives for former mine sites

A review of studies on sustainable development in mining life cycle

Mine land rehabilitation: Modern ecological approaches for more sustainable mining

Assessing the development of rehabilitated grasslands on post-mined landforms in north west Queensland, Australia

This study depicts broad-scale revegetation patterns following sand mining on North Stradbroke Island, south-eastern Queensland, Australia. Based on an ecological timeline spanning 4–20 years post-rehabilitation, the structure of these ecosystems (n = 146) was assessed by distinguishing between periods of ‘older’ (pre-1995) and ‘younger’ (post-1995) rehabilitation practices. The general rehabilitation outlook appeared promising, whereby an adequate forest composition and suitable levels of native biodiversity (consisting of mixed-eucalypt communities) were achieved across the majority of rehabilitated sites over a relatively short time. Still, older sites (n = 36) appeared to deviate relative to natural analogues as indicated by their lack of under-storey heath and simplified canopy composition now characterised by mono-dominant black sheoak (Allocasuarina littoralis) reaching up to 60% of the total tree density. These changes coincided with lower soil fertility parameters (e.g., total carbon, total nitrogen, and nutrient holding capacity) leading us to believe that altered growth conditions associated with the initial mining disturbance could have facilitated an opportunistic colonisation by this species. Once established, it is suspected that the black sheoak’s above/belowground ecological behaviour (i.e., relating to its leaf-litter allelopathy and potential for soil-nitrogen fixation) further exacerbated its mono-dominant distribution by inhibiting the development of other native species. Although rehabilitation techniques on-site have undergone refinements to improve site management, our findings support that putative changes in edaphic conditions in combination with the competitive characteristics of some plant species can facilitate conditions leading to alternative ecological outcomes among rehabilitated ecosystems. Based on these outcomes, future studies would benefit from in depth spatio-temporal analyses to verify these mechanisms at finer investigative scales.

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Structural development of vegetation on rehabilitated North Stradbroke Island: Above/belowground feedback may facilitate alternative ecological outcomes

Following mineral sand mining on North Stradbroke Island, southeast Queensland, rehabilitation managers have a statutory obligation to restore vegetation communities to meet completion criteria based on representative native 'reference' communities. The success of rehabilitation is currently evaluated by measures of vegetation composition and structure, with native tree and understorey species richness, density and foliage cover required to achieve at least 65 to 75% of reference site values. Rehabilitation aged 8, 10, 15 and 20 years was assessed in the Gordon mine lease area and compared with prescribed reference communities, representative of four eucalypt dominated communities on the island. Ordinations of species composition showed that rehabilitated sites were more similar to each other than to the reference sites. In contrast to reference sites, 15 and 20-year-old rehabilitation was dominated by Allocasuarina littoralis and recorded low species richness. Recently rehabilitated areas were more similar to reference sites with predominantly eucalypt tree species and comparable species richness. Native species density was lower in rehabilitation of all ages (29 to 114 stems/40 m2) compared to reference sites (237 to 368 stems/40 m2). Without management intervention, it is unlikely that 15 and 20-year-old rehabilitation will progress toward the reference sites and with continued exclusion of fire, younger rehabilitation may also become progressively dominated by a simplified stand of A. littoralis. The value of comparing developing ecosystems to successionally 'mature' communities is considered and implications for selecting reference values and choosing management interventions are discussed.

Evaluating the success of mineral sand mine rehabilitation on North Stradbroke Island, Queensland: Comparisons with reference eucalypt communities

A closure objective of Kidston Gold Mines Limited was to return a self-sustaining savannah woodland 
vegetation of native trees and introduced and native ground cover species to areas disturbed by its Kidston 
mining operation. One of the major areas of disturbance was the 310 ha tailings storage facility (TSF) into 
which approximately 68 Mt of tailings were deposited between 1985 and 1996. Early revegetation trials 
conducted in the early-mid 1990s demonstrated the capacity of the tailings to support vegetation growth 
without the requirement for a capping layer of soil or other cover material. The tailings storage facility was 
decommissioned at the end of 1997 and as the accessible area on the surface of the facility became 
progressively available (from March 1998 through to December 2001), planting and seeding of over 50 
native tree and shrub species and 8 introduced and native pasture species was undertaken. With the support 
of drip irrigation over the first few months and initial fertilisation, the alkaline tailings have proven to 
successfully support the establishment and growth of a range of native tree and shrub species. Greatest 
success with upper-and mid-storey species has been where competition from introduced grasses has been 
minimised. 
Since 2001, up to four areas of different aged rehabilitation across the surface of the TSF have been 
monitored on an annual or biennial basis by The University of Queensland's Centre for Mined Land 
Rehabilitation (CMLR). The overall aim of the Kidston monitoring program has been to assess the 
progressive development, functioning and composition of the rehabilitation areas prior to relinquishment by 
the company. This paper presents some background on rehabilitation works and research trials undertaken on 
the tailings and reports on the most recent findings from the vegetation monitoring that has been conducted 
on the four TSF sites (TD40, TDNA, TDNB and CTD) in the period 2001 to 2005. The 2005 findings are 
presented in relation to two unmined analogue communities and preliminary rehabilitation targets. 
Monitoring against these interim targets has proven to be a valuable process for tracking the structural and 
functional development of these vegetation communities. In addition, an ongoing assessment of the tailings 
attributes contributes to our understanding of soil development processes and hence the longer–term 
sustainability of the reconstructed ecosystem as the company aims towards lease relinquishment.

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An Assessment of the Direct Revegetation Strategy on the Tailings Storage Facility at Kidston Gold Mine, North Queensland, Australia

Tarong Coal Meandu Mine and Kunioon Test Pit Rehabilitation Monitoring and Compliance with EA Criteria. 2011 Assessment. Report to Stanwell Corporation, June 2012

A. J. Gravina

Papers

Assessing the development of rehabilitated grasslands on post-mined landforms in north west Queensland, Australia

Structural development of vegetation on rehabilitated North Stradbroke Island: Above/belowground feedback may facilitate alternative ecological outcomes

Evaluating the success of mineral sand mine rehabilitation on North Stradbroke Island, Queensland: Comparisons with reference eucalypt communities

An Assessment of the Direct Revegetation Strategy on the Tailings Storage Facility at Kidston Gold Mine, North Queensland, Australia

Tarong Coal Meandu Mine and Kunioon Test Pit Rehabilitation Monitoring and Compliance with EA Criteria. 2011 Assessment. Report to Stanwell Corporation, June 2012