Land Reputation Notes

Land Reputation

Soil Biological Fertility

  • Human-induced land degradation is driven by:
    • Overgrazing
    • Deforestation
    • Agriculture
    • Urban development
    • Industrial activities (e.g., mining)
  • Land degradation can result in soils being lost 10-100 times faster than natural formation rates.
  • Land area directly altered by mining is relatively small globally (e.g., Australia: 0.05%, China: 0.2%, South Africa: 1%).
  • Impacts of mining can be severe and spread off-site.

Mining in Australia

  • Mining contributes significantly to the Australian economy.
  • Key aspects of mining in Australia:
    • Coal: Largest exporter, fourth-largest producer
    • Gold: Second-largest producer after China
    • Bauxite: World's largest producer
    • Iron Ore: Third-largest supplier after China and Brazil
    • Base Metals: Nickel, copper, zinc
    • Mineral sands
  • Australia has over 350 operating mines.
  • Major mining areas: Western Australia, Queensland, New South Wales
  • Abandoned or closed mines pose environmental and safety challenges, including contamination, erosion, and water pollution.
  • Efforts are underway to rehabilitate these sites through regulatory frameworks and remediation programs.

Mining-Associated Activities

  • Identification and evaluation of mineral resources via geological surveys, drilling, and sampling.
  • Extraction: Removing minerals from the ground (surface or underground).
  • Milling, processing, refining, and waste disposal.

Mining Methods

  • Underground Mining:
    • Accessing ore bodies deep underground (e.g., coal, gold).
    • Land disturbance: Subsidence, surface spoil heaps, tailings storage.
  • Strip Mining:
    • For mineral ores like bauxite and diamonds.
    • Land disturbance: Vegetation removal, topsoil removal, stockpiles of overburden rocks and soil, habitat loss.
  • Dredge Mining:
    • For placer deposits in water.
    • Land disturbance: Moderate disturbance to wetlands, riverbeds, and coastal areas; vegetation removal; creation of ponds.
  • Open Pit Mining:
    • For metal ores.
    • Land disturbance: Steep pits, waste facilities, large-scale surface disturbance.
  • Long-term environmental impacts: Acid mine drainage, dust, and water contamination.

Terminology

  • Reclamation: Returning land surface to some form of beneficial use.
  • Restoration: Process guided by ecological principles to promote recovery of ecological integrity.
  • Regradation: Progressing towards ecosystem restoration.
  • Ecosystem Reconstruction: Reinstallation of the original ecosystem in all its structure and functional aspects.

Ecological Restoration

  • Aims to initiate and accelerate the recovery of a disturbed ecosystem towards a target state.
  • Key Concepts:
    • Thresholds and tipping points: Ecosystems may not recover naturally after crossing certain thresholds.
    • Importance of soil health: Rebuilding soil biodiversity and structure is crucial.
    • Restoration vs. Succession: Active restoration is often necessary when conditions are severely degraded.

Framework for Restoring Mine-Affected Landscapes

  1. Define the restoration goal/endpoint:
    • Set ecological, social, or land use outcomes.
    • Return to native vegetation, pasture, or functional land.
  2. Determine measurable success criteria:
    • Vegetation coverage, soil stability, biodiversity levels.
  3. Topsoil Handling:
    • If retained: Focus on reshaping landforms and erosion control.
    • If lost: Assess waste geochemistry and prepare sites through remediation or capping layers.
  4. Revegetation:
    • Select native or suitable species.
    • Apply nutrients and encourage microbial activities.
    • Use fertilizers or legumes to restore soil fertility.
    • Example: Lupins as pioneer plants.
  5. Adaptive Management:
    • Modify approaches based on performance (replanting, pest control, fire management).
  6. Monitoring:
    • Track progress, measure regularly using defined measures.
  7. Assessment of success criteria:
    • Evaluate if the project has met defined goals and criteria for long-term sustainability.

Case Study: Bauxite Mining and Reputation in Western Australia

  • Bauxite is an ore rich in aluminum oxide.
  • Australia is a major producer of Bauxite.
  • Steps:
    • Bauxite ore is mined and transported to refineries to extract alumina (Al<em>2O</em>3Al<em>2O</em>3).
    • Alumina undergoes smelting and fabrication into aluminum products.
  • Major Bauxite Mining Areas in Australia:
    • Western Australia (Alcoa operations: Huntley, McCoy, Milodale; refineries in Kwinana, Pinjarra, Wagerup)
    • Northern Territory (Gove - Rio Tinto operation)
    • Queensland (Weipa)
  • Australia is the second-largest producer of alumina after China (around 20,000,000 tons annually in 2020).
  • Major export destinations: China, USA.
  • Approximately 90% of alumina is exported for aluminum smelting.

Bauxite Mining and Reputation in Western Australia

  • Mining takes place in the Jarrah Forest on the Darling Plateau.
  • Bauxite mining and forest reputation has been active for over 45 years.
  • Huntley and Willowdale are active sites and among the largest bauxite producers worldwide.
  • Approximately 550 hectares are mined and replicated annually (around 15,000 hectares of forest to date).

Jarrah Forest

  • Dry sclerophyll forest/woodland in Southwestern Australia (approximately 3,300,000 hectares).
  • Dominated by Eucalyptus species (Jarrah and Marri).
  • Mid-story: Banksia and sheoak trees.
  • Diverse understory: Shrubs, ground cover, fungi.
  • One of the most pollinator-rich forest ecosystems in Australia.
  • South West Australia is a biodiversity hotspot.
  • Over 1,200 plant species, 29 mammals, 45 reptiles, 14 frogs, and around 150 bird species.
  • Managed by the Western Australia government for multiple purposes (timber, recreation, water catchment).

Bauxite Mining Process in Southwestern Australia

  • Shallow operation (4-5 meters deep) in small areas (1-10 hectares).
  1. Pre-mine surveys: Check for operational heritage sites, dieback disease, flora, and fauna.
  2. Exploration drilling to map bauxite deposits.
  3. Land is cleared, and timber is harvested.
  4. Soil is stripped in two layers: Topsoil (15 cm) and overburden (15-40 cm).
  5. Blasting may be needed to break up hard rock.
  6. Bauxite ore extracted.
    • Only 40-50% of mining area is disturbed.
  • Mined or unmined or progressively restored forest.

Forest Revitalization After Bauxite Mining

  1. Landscaping and pre-raking to shape the land and prepare the soil.
  2. Subsoil and topsoil returned to the site.
    • Reintroduces native seeds and soil microbes.
  3. Ripping and creating mounds to improve water infiltration and reduce erosion.
  4. Seeding with a mixture of around 100 native plant species (Jarrah forest species used exclusively after 1998).
    • High proportion of legumes fix nitrogen from air
  5. Planting seedlings by hand.
  6. Site is fertilized.
  7. Pest control (if needed).

Progress of Forest Recovery Following Reputation on Bauxite Mine Site

  • Visually:
    • The images displayed the progress of a barren site, 7-8 year old forest, 12-13 year old forest, and then 18-20 year old forest.
  • The 18-20 year old forest closely resembles the original Jarrah Forest.

Replication Completion Criteria

  • Goal: Create a self-sustaining forest ecosystem.
  • Criteria:
    • Meet intended land use objectives (water catchment, timber production, recreation).
    • Visually/ecologically integrated into the surrounding landscape.
    • Show sustained growth and nature development over time.
    • Be resilient (like the native Jarrah Forest) and able to handle forest management practices (prescribed burning).

Measuring Rehabilitation Progress

  • Long-term monitoring plots to follow forest development (slow to show results and challenging to maintain).
  • Practical approach: Organic surveys at different times (e.g., 9 months, 12 months) and long-term rehabilitation and monitoring reports.
  • Ambitious Goal: Restore 100% of the plant species present in the Jarrah Forest.
  • Chronosense design (space for time substitution): Compares repetitive size of different ages to estimate long term trends in forest recovery (limited if management practices change).

Research Project on Soil Recovery in Jarrah Forest Replication

  • Investigating four key aspects of recovery:
    1. Recovery of soil carbon and nutrients.
      • Checking carbon, nitrogen, phosphorus return to pre-mined levels.
    2. Recovery of microbial biomass and activity.
      • Measuring soil microbes, decomposition, and nutrient recycling.
    3. Recovery of nitrogen cycling processes.
      • Examining how nitrogen is transformed and made available to plants.
    4. Recovery of microbial community structure.
      • Identifying shifts in types and diversity of microbes.
  • Observing how these properties change across the size of different ages.

Findings Observed from Soil Recovery in Jarrah Forest Studies

  • Studied replication sites of different ages (3, 6, 10, 14, 18, 26 years old), compared to undisturbed Jarrah Forest.
  • Total organic carbon increased with age of reparation but was still lower than in non-mined reference forest after 26 years.
  • Total soil nitrogen began to recover more noticeably after 18 years.
  • Dramatic loss (80%) of microbial population right after mining.
  • Steady recovery of microbial biomass carbon over time.
  • By around 10-15 years post-repetition, showed significant improvement.
  • Recovered Essential role of microbes in nutrient cycling and supporting plant growth was supported.
  • Younger sites are more distinct, while older rehabilitation sites gradually cluster closer to the non-mined forest site which shows recovery of microbial diversity and structure.

Summary

  • Land reputation is about restoring entire ecosystems, not just the ground.
  • Soil health and below ground processes play a vital role in successful reputation, and a functional soil system is required for complete forest recovery.
  • In Western Australia, land utilization is essential for sustainable land management, given the scale of mining.
  • The Java Forest case study provides a hopeful message that careful planning and long-term commitment can achieve successful recovery.