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Accueil du site → Doctorat → Australie → 2003 → Developing completion criteria for rehabilitation areas on arid and semi-arid mine sites in Western Australia

Curtin University of Technology (2003)

Developing completion criteria for rehabilitation areas on arid and semi-arid mine sites in Western Australia

Darren Brearley

Titre : Developing completion criteria for rehabilitation areas on arid and semi-arid mine sites in Western Australia

Auteur : Darren Brearley

Grade : Doctor of Philosophy PhD 2003

Université de soutenance : Department of Environmental Biology. Curtin University of Technology,

Résumé partiel
Continued expansion of the gold and nickel mining industry in Western Australia during recent years has led to disturbance of larger areas and the generation of increasing volumes of waste rock. Mine operators are obligated to rehabilitate all disturbed surfaces and reconstructed landforms, and considerable effort and expense is now applied to the achievement of this objective. Associated with increasing rehabilitation effort is the requirement to accurately judge rehabilitation success through the development of completion criteria. Completion criteria are rehabilitation performance objectives set as conditions of approval for each stage of rehabilitation and for the project as a whole. They provide standards against which the success of rehabilitation can be measured, or more broadly the point at which responsibility for rehabilitation is complete. The current research project tackles the development of completion criteria by investigating ecosystem function within a variety of rehabilitation trials at four mine sites located in arid and semi-arid Western Australia, and also within surrounding ’natural’ vegetation complexes undisturbed by mining, termed analogue sites. Six specific objectives were identified as part of the study : 1. To establish an appropriate end point land use for each mine site where field trials were established ; 2. To examine long-term ecosystem development through the assessment of revegetation at a variety of rehabilitation sites ; 3. To examine functional components within analogue communities and make appropriate comparisons with rehabilitation trials ; 4. To record the potential reproductive capacity of revegetation progeny, and determine how this relates to ecosystem function ; 5. To provide a better understanding of ecosystem function by investigating the relationship between state factors, interactive controls, and ecosystem processes at rehabilitation and analogue sites ; and 6. To develop a methodology for establishing realistic environmental completion criteria at mine sites situated in arid and semi-arid Western Australia. Field trials were established at four mine sites located within three subtly different bioclimatic zones that extend through the arid / semi-arid shrubland belt of Western Australia ; Northeastern Goldfields (Granny Smith Gold Mine, Sunrise Dam Gold Mine), Eastern Goldfields (Black Swan Nickel Mine), and Northeastern Wheatbelt (Westonia Gold Mine). 1 The re-establishment of a self-sustaining vegetation cover integrated with the surrounding ecosystem, was the common end land use objective at the four mine sites selected for this study. For three sites located in the Northeastern Goldfields and Eastern Goldfields of Western Australia, sheep were grazed on surrounding rangeland ; the fourth site located in the Northeastern Wheatbelt of Western Australia, and was surrounded by Crown Land. 2 To better understand ecosystem function, the dynamic behaviour and interaction of plant biodiversity parameters was monitored regularly at 19 post-mining rehabilitation sites up to 11 years after direct seeding. For functional ecosystems, plant biodiversity parameters changed rapidly during the initial five years after seeding following predictable trends, after which time they remained within a relatively stable range. The stabilising of parameters over time was identified as a key indicator of rehabilitation success, however the point at which the parameters stabilised was influenced by numerous variables and was difficult to accurately predict. Prolific seed germination resulted in high seedling density during the initial growing season. Plant density then progressively decreased in response to competition, before stabilising within a range approximately five years after seeding. Revegetation cover was typically low during the first growing season, increasing rapidly there after before also stabilising in line with plant density. Maximum species richness was generally achieved during the first and second year when annual Atriplex species were prominent. Perennial Atriplex species established more slowly during the early stages of revegetation development, but eventually replaced the annual component as the dominant taxa. Perennial Maireana species required up to three years before germinating in the field and establishing themselves in the revegetation ; in many cases they replaced perennial Atriplex as the prominent taxa. The presence or absence of cyclonic rainfall during the first growing season was a major determinant of the ecosystem trajectory, controlling revegetation structure and composition.

Mots clés : revegetation of mine sites, mine rehabilitation, rehabilitation objectives

Présentation et résumé (National Library of Australia)

Page publiée le 8 mars 2007, mise à jour le 30 mai 2017