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Topsoil TranslocationOne step from the tip

a wasted resource

or …from bitumen to

bush in a few steps…

Mark Walters Teacher - NSI Ryde TAFE

Let me start with a question

“How do you revegetate this degraded environment?”

A severely degraded environment, • Poor abiotics (bitumen, gravel, no natural soils)• Poor biotics (no native species or resilience, no beneficial

soil micro-organisms, abundant in weeds and weedy resilience)

• Will planting do???

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What is topsoil translocation?

“…moving seed-rich topsoil from good bushland to be developed (Donor) to a degraded site (Recipient)…”

• Builders send topsoil to landfills at great expense, or it is composted to provide landscaping topsoil.

• We are wasting a resource - the seed stored in the topsoil;• 89% of Sydney native species store seed in topsoil.• 80 – 90% of those seed are in top 5cm of the soil.

• Poorly used & understood in New South Wales, but used in Europe and Western Australia.

How is it done?

Fig 3: Recipient site readyFig 2: Topsoil strippingFig 1: Donor Site –Slash understorey & tree lopping

Fig 6: Plants in topsoil Fig 4: Topsoil layingFig 5: 18 months later

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So a possible answer is this…..

8 years later

What are the benefits? • As a Planning Tool

– Conserve biodiversity– Practical conservation of some ecological attributes– Planning tool of last resort “ as a condition of consent ”– Planning tool of last resort …as a condition of consent…

• As a Site Rehabilitation tool– Better ecological outcomes than traditional revegetation

• Greater species diversity• Topsoil’s abiotic & biotic features - optimum mix for reveg• Overcomes many limiting thresholds in revegetation (biotic & abiotic)

– Cheaper rehabilitation method.• ‘Set and forget’ approach – minimal weeding• Cost burden on developer as a condition of consent

General Question: Does the method work in Sydney’s sandstone areas?

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THE CASE STUDY: JJ Hills, Terrey Hills: Warringah Council

In Duffys Forest Vegetation Community a translocation opportunity presented itselfpp y p– an Endangered Ecological Community TSC Act 1995– 16% left, highly fragmented, confined to ridges

The Development site (Donor site) could not be saved– Already failed a Flora and Fauna (7 part test) & Species Impact

Statement (SIS)

A Council Consent Condition required the translocation of A Council Consent Condition required the translocation of the seed rich topsoil to a revegetation site– Developer pays and an opportunity to study the results

General Question: Does the method work in Sydney’s sandstone areas?

Study Sites• Terrey Hills – Sydney Northern BeachesDonor Site - Duffys Forest Vegetation

Recipient site - Former landfill site

Reference sites (REF) Reference sites (REF) -• 6 sites in 3 Age Classes• 19, 60 & 120 months since

fire

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Fast, Cheaper $$$

Costs $$$ vs. Plant outcomes

We asked 5 Questions - Questions 1 to 3

Slow, high $$$ Vs.

Q1. Does Leaf litter location have an effect?

On-top vs. Mixed-inSeparated with later top-dressing Non-separation at stripping

Q2. Do plants need a subsoil beneath the topsoil?

Subsoil-present vs Subsoil-absentSubsoil present vs. Subsoil absent

Q3. Are post-translocation germination stimuli needed?

Burnt vs. Smoke-products vs. Disturbance

Translocation vs Reference sites

Five Questions – Questions 4 & 5Two questions at study end, did the process

create a ‘natural’ outcome?

Translocation vs. Reference sites

Q4. Are vegetation structure and cover similar?

- Structure stratum - Ground cover - litter layer types

Q5. Are the ant communities similar?RESULTS NOT REPORTED

Ants are regarded as useful bioindicators for a variety of disturbances

e.g. Mining, Fire regime, Differing land use, Habitat disturbance

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Recipient Site JJ Hills - Plots Established

24 Experimental lots created (each plot 4-5 m x 10 m)

Factorial TreatmentsGermination - Burning vs. Smoke product vs.

Disturbance alone • 8 plots each

Leaf litter - mixed-in & ontop• 12 plots each

S b il P Ab tSubsoil – Present vs. Absent• 12 plots each

Q1 – 3: Leaf litter, Subsoil & germination treatments

SAMPLED: 5th, 19th, 40th and 60th months

Translocation Sites only

QUADRATS : Species and stem densities in 1m x 1m quadrats (2 quadrats per plot = 48 quadrats).

Figure 1: 60 months of growth note large number of Gum trees recruiting to site

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Sampling Q4: Vegetation Structure

Timing: 60th month

Translocation vs. Reference Sites

Cover in stratum>2m x 2m quadrats % cover estimated by eye for;

>Canopy >Midstorey

>Ground >litter type and depth>Translocation n =48; Ref sites n =96

Foliage Cover upto 2m in 20cmFoliage Cover upto 2m in 20cm increments

>2m Levy Pole - no. of live/dead contacts in each 10 x 20cm pole graduation.

>Pole Placements >Translocation n =96; Ref sites n =192

Q1: Results - Leaf Litter location Native Species Weed Species

Native spp. for On-top & Mixedfollowed same trajectory

Native spp 4 – 10 x more than weed

Vs

Native spp. 4 – 10 x more than weed

* p<0.01, other results not sig.

*

Native stems for On-top & Mixedf ll d t j tfollowed same trajectory

Native stems >> than weeds

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Q2: Results -Subsoil Present or AbsentNative Species

S i Ri h / 2

Weed Species

Native spp. for treatments follow same trajectory

Native spp 6–10 x >> weeds

Vs

Species Richness / m2 Native spp. 6–10 x >> weeds

Native stems for treatments

No significant results

follow same trajectory,

Natives stems >> weeds

Q3: Results -Germination treatmentsNative Species

S i Ri h / 2

Weed SpeciesTreatments converge at 40+ months

Native species 5 to 12 times more than weed sp. (Particularly burnt)

Vs

Species Richness / m2

N ti t 5 t 100 ti (Di t

Stem density converge at 40+ months

Native stems 5 to 100 times (Dist & Burnt) more than weed stems

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Translocation vs. Reference Sites - MDS Plots Q4 Levy Pole Results I: Veg Structure – MDS Plot

Translocated plots most similar to

same or older age class REFsitesclass REFsites

All Data were arcsine transformed; 30 repeats; Numbers = months; Contour lines shows single linkage Bray-Curtis similarity)

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3

4

pth

(cm

)

Leaf Litter depth (inc. SE bars) show 60 month translocated sites

= younger REF19 months

Translocation vs. Reference Sites - Graphs

Q4 Results: Litter Depth (cm)

0

1

2

t s e 9 0 0

Litte

r dep

y g

Bur

nt

Smok

ePr

oduc

t s

Dis

turb

ance

REF

19

REF

60

REF

120

Translocation Site Reference Sites

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Q4: Levy Pole in reference sites – ‘bush’

Q4: Levy Pole Results - translocation

Dense

Disturbance & Smoke treatments more similar

age class up high

Hollow under layer

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Conclusion – The General answerThe process worked resulting in;

1. High biodiversity outcomes• 35 - 70 seedlings/sqm ., • 6 - 12 species /sqm.,• 46 native species >> 42 spp. recorded on donor site!• Another site had 70+spp. vs. 106spp. before

Study shows cheaper options work;• No leaf litter separation or Subsoil required• Germination treatments converged after 40 months

Future study areasFuture study areas• Plant canopy species after translocation, or • Bring in donor canopy brush to the site• Use Burning, if weed invasion risk at recipient site • Burn donor site before removal?• Spread thinner topsoil depth permitting more area coverage?• No topsoil, Leaf litter alone?

Problems Managing a translocation

• Consent Conditions & Specifications not clear• Builder delivered subsoil, believing the topsoil is “rubbish”

• Council’s DA conditions translocation, but Construction Certificate ,CC, needed only AFTER veg clearance >> inappropriate clearance and damaged soils and plants

• Site clearance and then not translocating

• Not using experienced specialists• Excavation contractors / miners to do the work and mixing

t il i t b il dil ti db ktopsoil into subsoil – diluting seedbank

• Stockpiling topsoil• Seedbank killed by stockpiling – composting (recently

stockpiles measured at 50oC. midwinter)

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Same photopoint Top: Completed site Bottom : 8 years later

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Some References– Auld, T. and M. Tozer (1995). "Patterns in Emergence of Acacia and Grevillea Seedlings

after Fire." Proceedings of the Linnean Society of New South Wales 115: 5-15.– Grant, C. D., D. T. Bell, et al. (1996). "Implications of seedling emergence to site restoration

following bauxite mining in Western Australia " Restoration ecology 4(2): p146-154following bauxite mining in Western Australia. Restoration ecology 4(2): p146 154.

– Koch, J. M., S. C. Ward, et al. (1996). "Effects of bauxite mine restorations on topsoil seed reserves in the jarrah forest of Western Australia." Restoration Ecology 4(4): p368-376.

– Good, J. E. G., H. L. Wallace, et al. (1999). "Translocation of Herb-Rich Grassland from a Site in Wales Prior to Opencast Coal Extraction." Restoration Ecology 7(4): 336-347.

– Pywell, R. F., N. R. Webb, et al. (1995). "Comparison of techniques for restoring heathland on abandoned farmland." Journal of Applied Ecology 32(2): 400-411.

– Rokich, D. P., K. W. Dixon, et al. (2000). "Topsoil Handling and Storage Effects on W dl d R i i W A li " R i E l 8(2) 196 208Woodland Restoration in Western Australia." Restoration Ecology 8(2): 196-208.

– Vecrin, M. P. and S. Muller (2003). "Top-soil translocation as a technique in the re-creation of species-rich meadows." Applied Vegetation Science 6: 271-278.

– Ward, S. C., J. M. Koch, et al. (1996). "The effect of timing of rehabilitation procedures on the establishment of a jarrah forest after bauxite mining." Restoration ecology 4(1): p19-24.

– Ward, S. C., J. M. Koch, et al. (1997). "Ecological aspects of soil seed banks in relation to bauxite mining, I: unmined jarrah forest." Australian journal of ecology 22(2): p169-.