Native rehabilitation of grossly disturbed sites: the answer lies in the soil and engineers

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Native rehabilitation of grossly disturbed
sitesthe answer lies in the soil (and
engineers)
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Outline

• What is grossly- disturbed?
• Rehabilitation
• - defined
• - as part of the
• RMA toolkit
• Five worst practices
• Five best practices

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Grossly disturbed sites

• Removal of vegetation and soils
• Change in topography
• Degradation of topsoil living to dead or absent

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Gross disturbance degraded soils

• Increased runoff surface water flow
• (due to less infiltration, less storage, removal
  of watercourses)
• Stressed plants
• (due to smaller rooting volumes, less oxygen and
  water,
• damaged soil biota,
• disrupted carbon cycling)

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DefinitionRehabilitation

• It is very rare that we can restore
• we hope to rehabilitate, i.e. create similar
  ecosystems, or
• create new, different ecosystems.

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Rehabilitation one of 3 prongs
1. Avoid (the preferred option) 2. Remedy on
site rehabilitation 3. Mitigate off-site
protection management
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Five worst practices

• Poor planning
• Poor topsoil management
• Poor surface management
• Short or no maintenance period
• No learning
• no monitoring or evaluation of results

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Poor road planning
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How to degrade (top)soil

• Degrade topsoil during stripping mix it with
  topsoil, retain weeds
• Stockpile soil gt3m height using scrapers, and
  allow erosion, avoid plant cover
• Let machines traffic rehab areas especially
  when soils are wet
• Maximise plant stress shallow soil, poor
  physical condition, use weed mat (retard
  amelioration).

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Four best rehab practices

• Early and effective planning
• Maximum salvage, quality
• reuse of rehab resources
• scheduling critical
• Educated, enabled
• engineers digger drivers
• Maintenance
• Assessment of performance
• against goals

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Topsoil is gold
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What if topsoil is weedy?
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Salvage rehabilitation resources

• Plants
• Plant soil sods
• Topsoil
• Coarse wood
• Rocks huge
• 100-200 mm

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Resource plant - soil sods
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Large sods are great
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Pre-treatment of sods

• Robyn Simcock, Mark Smale, Craig Ross
• Landcare Research NZ Ltd
• Auckland
• Hamilton
• Palmerston North

Response of sods
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Resource coarse wood
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How to maximise plant performance

• Use and sustain a living topsoil to 200 mm
• Get plants growing with minimum stress - maximise
  rooting depth, aeration, carbon
• Minimise risk stable sites, pest control, avoid
  machine traffic
• Mulch if not wet (not weedmat)

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Roadside revegetation booklets

• Good and bad road batter maintenance
  rehabilitation practice
• Auckland motorways field day record
• Maintaining and revegetating roadsides
• handbook (Transfund)
• Website in June - drop me an email for pdf
• SimcockR_at_landcareresearch.co.nz

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The Foundation for Research, Science and
Technology Transfund, Solid Energy, Department of
Conservation assisted this research