Native Grass Establishment - salisbury.sa.gov.au · Native Grass Establishment: the battle with...
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Native Grass Establishment: the battle with invasives occurs below ground
Monique Smith, PhD Candidate Supervisor: José M. Facelli
Terrestrial Plant Ecology Laboratory, School of Biological Sciences
The Battle of Grassland Restoration
University of Adelaide 2
Battle Field Old-fields at Para Woodlands
The Battle of Grassland Restoration
University of Adelaide 2
Battle Field Old-fields at Para Woodlands
Opponents Invasive annual grasses
vs Native perennial grasses
The Battle of Grassland Restoration
University of Adelaide 2
Battle Field Old-fields at Para Woodlands
Opponents Invasive annual grasses
vs Native perennial grasses
The Battle of Grassland Restoration
Battle Field Old-fields at Para Woodlands
Opponents Invasive annual grasses
vs Native perennial grasses
‘Root’ to Victory Know your enemy!
Nutrient availability, soil microbes & resource use
University of Adelaide 2
University of Adelaide 6
N +
Invasive grasses
Native grasses
-
Nutrient availability
Invasive species can • Take advantage of increased nutrients • Maintain higher soil nutrient
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Soil microbes
Important for plant growth • Pathogens, aeration of soils & controlling nutrient
cycles
Weed invasions may change microbial communities • Changes in the organic matter, root exudates, root
structures
Changes may be too great to support native revegetation
• Particularly in degraded systems like old-fields
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Resource use • Successful restoration achieved by selecting native
species with a diversity of functional traits
• Invasive species will be unlikely to establish if their niches are occupied
Gro
wth
S A W S
C4 Native C3 Native C3 Invasive (annual)
Research questions
University of Adelaide
1. Site preparation • Which weed management techniques can reduce
nutrient availability & improve native grass growth?
Research questions
University of Adelaide
1. Site preparation • Which weed management techniques can reduce
nutrient availability & improve native grass growth?
2. Microbial communities • How do soil microbial communities influence
restoration outcomes?
Research questions
University of Adelaide
1. Site preparation • Which weed management techniques can reduce
nutrient availability & improve native grass growth?
2. Microbial communities • How do soil microbial communities influence
restoration outcomes?
3. Planting strategies • Can incorporating functional diversity & resource use
into planting strategies make revegetated communities more resilient?
Overall aim - to gain a better understanding of the mechanisms involved in successful restoration Application – reducing nutrient availability and weed competition to tip the balance in favour of natives
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Site preparation
Site prep. - methods Experimental design • Weed management (3 m2 x 6 reps)
• Slash + remove • Burning • Scalping • Control
• Reducing nutrients (1 x 2 m subplots) • +/- Carbon • 0.5 kg/m2 sugar • 0.4 kg/m2 sawdust
• Planting tubestock and direct seeded Rytidosperma caespitosum
University of Adelaide
Site prep. - methods Measurements after 5 months • Soil conditions
• Changes in nutrients • Microbial community composition
• Success of weed management • Total biomass of different species
• Native grasses • Seedling emergence and mortality • Tubestock survival • Plant growth (biomass)
Rytidosperma caespitosum
University of Adelaide
Did the soil nutrients change?
University of Adelaide
Nitr
ate
Treatment Control Burn Scalp Slash
Carbon Supplement
No C
Add C
Did the soil nutrients change?
University of Adelaide
Carbon Supplement
No C
Add C
Treatment Control Burn Scalp Slash
Phos
phor
us
How were the natives affected?
University of Adelaide
Carbon Supplement
No C
Add C
Treatment Control Burn Scalp Slash
Tube
stoc
k Bi
omas
s
What about the weeds? - tubestock
University of Adelaide
Carbon Supplement
No C
Add C
What about the weeds? – seeding
University of Adelaide
Carbon Supplement
No C
Add C
Site prep. - summary
University of Adelaide
Carbon addition • Reduced nitrate in soil • Reduced weed biomass Scalping was most successful at • Reducing phosphorus • Increasing native grass growth • Reducing weed biomass More data to come • Seedling emergence and mortality data
Soil microbes Compare performance of native & invasive grass species grown with soil microbial communities from
• an old-field • a remnant grassland
1) Does one invasive grass benefit from the
invasion of another invasive grass?
2) Do remnant microbial communities benefit native grass growth and establishment?
University of Adelaide
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Soil microbes - methods Control (sterile) Commercial grade soil, autoclaved twice Treatment (sterile soil inoculated with 20%) Old-field – dominated by annual weeds
Remnant – diverse native grassland
Lolium rigidum
Austrostipa nodosa
Rytidosperma auriculatum
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Were the bacterial species different?
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Were the fungal species different?
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Soil microbes – plant mortality
Rytidosperma (wallaby)
Austrostipa (spear)
Lolium (weed)
% M
ort
ali
ty
S te r ile D e g ra d e d R e m n a n t0
2 0
4 0
6 0
8 0
In o c u la n t T y p e
Old-field Remnant Sterile
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Soil microbes – plant growth
L o liu m r ig id u m (w e e d )M
ea
n t
ota
l b
iom
as
s (
g)
S te r ile O ld f ie ld R e m n a n t0
1
2
3
4
In o c u la n t T y p e
*
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Soil microbes – plant growth
A u s tro s t ip a n o d o s a(S p e a r g ra s s )
Mea
n to
tal b
iom
ass
(g)
S te r ile O ld f ie ld R e m n a n t0
1
2
3
In o c u la n t T y p e
*
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Soil microbes – plant growth
R y t id o s p e r m a a u r ic u la tu m(W a lla b y g ra s s )
Mea
n t
ota
l bio
mas
s (g
)
S te r ile O ld f ie ld R e m n a n t0 .0
0 .5
1 .0
1 .5
2 .0
In o c u la n t T y p e
*
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Soil microbes - summary
Weed response • Lowest mortality overall • Not fussy with which microbes are present Native response • High mortality with old-field microbes • Increased growth with remnant microbes Applications • Incorporating microbial inoculation into restoration
programs may be beneficial for native grasses
Planting strategies Is the resilience of revegetated communities increased by:
1) Functional group diversity?
2) Planting density?
How do the natives respond to these planting strategies?
• Weeded plots to look at competition between natives
University of Adelaide
Resource use:
• Measure soil moisture for 12 months
• Nutrients at time of planting and in 12 months
C4 Native C3 Native C3 Invasive (annual)
University of Adelaide
Gro
wth
S A W S
A. flavescens, R. caespitosum, Enneapogan nigricans,
Themeda triandra
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Results to come!
Expected results Trade-off between resilience to weed invasion and competition between natives
• Fewer weeds but less growth of natives at high density
Overall fewer weeds where both C3 & C4 occur
• However, C3 have had an extra season
University of Adelaide
Summary • Incorporating below-ground restoration into above-ground
efforts may have huge implications for restoration outcomes
• Creating conditions suitable for native grass establishment
• Soil legacies
• Soil microbial communities
• Resource use
University of Adelaide
Weed Weed Weed Weed
University of Adelaide
Thank you
Supervisors: José M. Facelli, Leanne Rosser & Timothy Cavagnaro
… and many volunteers!
Friends of Private Bushland