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True restoration of highly disrupted native ecosystems is universally difficult, and has not been achieved on waste rock dumps at a rock phosphate mine in the resource-limited rangeland environment of semi-arid Queensland, Australia. Thirteen years after rehabilitation, there is general correspondence, but some temporal variation, in tree and shrub species richness between rehabilitated and analogue native vegetation sites. Large differences in the composition and extent of ground cover vegetation were associated with dominance of most sites by an introduced perennial pasture grass species and by periodic drought. Complete reinstatement of native ecosystems is shown to be inconsistent with the physical constraints of waste rock dumps, the erratic climate, the previous history of extensive grazing and a lack of effective rehabilitation planning. Revised goals of strict landscape stability and broad biodiversity attributes, based on those of relevant native ecosystem analogues, are proposed to enable the identification of appropriate native and novel ecosystem targets for the modified landscapes. Novel ecosystems combining tree and shrub components of the native vegetation, and ground cover (including introduced grasses) could provide the most effective targets for mined land rehabilitation in a semi-arid environment. Principles are suggested for the selection of vegetation targets for the rehabilitation of mine waste rock dumps, considering the new lithologies and landforms and the occurrence of a dominant introduced grass species. These principles should be applicable widely, but especially in resource-limited environments.

The Ernest Henry Mine in north west Queensland, Australia, is required to return disturbed land to native grassland and has been undertaking extensive revegetation of waste rock dumps since 2002. To ascertain the trajectories for revegetation success of these rehabilitated native grasslands, annual vegetation monitoring of both rehabilitation sites and selected reference areas has been undertaken since 2007. Long-term monitoring efforts have included assessments of vegetation composition, ecological structure and function at four rehabilitation areas (1–7 years post-rehabilitation) and proximal reference sites within surrounding grazed and ungrazed agro-ecosystems, undisturbed by mining. Our findings demonstrated that the oldest rehabilitated sites had similar species composition and functional elements to selected reference sites, although plant cover and biomass (particularly of native grasses) was lower than both grazed and ungrazed reference areas. The youngest sites had little established vegetation, however species richness was similar to the reference sites and functional life forms were present despite being in very low abundance. It is suggested that future monitoring events and informed management inputs (which consider local climatic conditions and soil fertility factors) could contribute to the development of a stable and sustainable native grassland thus achieving the desired end land use on these post-industrial landscapes.

Successional development at abandoned farmlands in southern Queensland, formerly occupied by sub-tropical rain forest is centred around scattered, isolated trees. Soil seed banks contain few woody plants and most tree species appear to be recruited from seed dispersed into the site by birds or bats. Scattered, low-growing trees 6 m in height that act as bird perches. The identity of these trees and whether or not they offer a fruit reward appears to matter less than their structure and suitability as a bird perch. The process of seedling recruitment may be accelerated when two or more trees form a cluster. The proportion of seedlings that survive and grow beyond 150 cm in height appears to be very small. Most of those that do can be classed as secondary rather than primary forest species, even though many primary forest species initially colonize the site. These observations were used to develop guidelines to accelerate the recovery of rainforest at degraded sites. The guidelines promote the early establishment of species that are usually poorly dispersed (e.g., large-fruited species), planted in scattered clumps. The guidelines should be suitable for situations where relatively large areas are in need of rehabilitation.

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.

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.