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Ecological impacts of invasive Pinus radiata

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<strong>Ecological</strong> <strong>impacts</strong> <strong>of</strong><br />

<strong>invasive</strong> <strong>Pinus</strong> <strong>radiata</strong><br />

Moira Williams and Glenda Wardle: School <strong>of</strong> Biological Sciences,<br />

University <strong>of</strong> Sydney


Invasion success<br />

Characteristics <strong>of</strong> the species<br />

- Superior traits<br />

- Greater plasticity<br />

Characteristics <strong>of</strong> environment<br />

Blackberry<br />

- Species rich areas resist invasion<br />

Propagule pressure<br />

Bridal creeper


Predicting Invasion Impacts<br />

Quantification <strong>of</strong> <strong>impacts</strong> to prioritise species<br />

Focus control and research efforts<br />

(Parker et al., 1999)<br />

Mimosa Salvinia Prickly Acacia


“Holy Grail <strong>of</strong> invasion biology”<br />

(Simberl<strong>of</strong>f, 2006)


Tree invasions<br />

Melaleuca quinquinervia<br />

in Florida<br />

Willow (Salix Spp.) in<br />

Australasia<br />

Acacia and Eucalyptus<br />

species in South Africa<br />

and Europe<br />

Pines in the southern<br />

hemisphere<br />

(Richardson et al 1994)


Why study pines?<br />

Known age and extent <strong>of</strong> source populations<br />

Extensive source <strong>of</strong> seeds in plantations<br />

<br />

<br />

Plantations expose a range <strong>of</strong> vegetation<br />

communities<br />

Conspicuous in native eucalypt vegetation


<strong>Pinus</strong> <strong>radiata</strong><br />

Restricted native<br />

range in California<br />

(~5000ha)<br />

Major timber crop<br />

Grown in large<br />

commercial<br />

plantations across<br />

Southern<br />

Hemisphere


P. <strong>radiata</strong> the invader<br />

South Africa (Richardson and Brown, 1986)<br />

New Zealand (Ledgard & Belton 1985)<br />

Australia (Williams & Wardle, 2005; Burdon & Chilvers 1977)<br />

Chile (Bustamante & Simonetti, 2005)<br />

Fynbos in South Africa<br />

Grasslands in New Zealand


<strong>Pinus</strong> <strong>radiata</strong> in Australia<br />

Major s<strong>of</strong>twood species<br />

~ 700,000 ha<br />

Majority grown in NSW and VIC<br />

Naturalised in all states it is grown<br />

Significant environmental weed<br />

(Randall & Kessal, 2004)


Invasion process<br />

• Densities <strong>of</strong> up to 1000/ha in<br />

areas close to plantation<br />

(Williams & Wardle 2005)<br />

• Long distance dispersal <strong>of</strong><br />

wildlings up to 4km from<br />

plantation<br />

• Second generation wildlings<br />

- creation <strong>of</strong> dense stands<br />

• Drier vegetation types more<br />

susceptible to invasion


Bird dispersal<br />

Yellow Tailed Black Cockatoo<br />

(Calyptorhynchus funereus)<br />

<br />

Feed on cones and carry seeds long distances


Our Research<br />

Determine the current extent <strong>of</strong> <strong>Pinus</strong><br />

<strong>radiata</strong> invasion in Australia<br />

Investigate factors facilitating pine spread<br />

Determine the ecological <strong>impacts</strong> <strong>of</strong><br />

invasion


Survey Methods<br />

Drive border <strong>of</strong> plantation<br />

Score level <strong>of</strong> pine infestation (0 to 5) every<br />

100m<br />

INFESTATION INDEX


29 plantations surveyed<br />

Extent <strong>of</strong> spread<br />

<br />

<br />

17 with no or little spread<br />

(Mean index


Lidsdale State Forest<br />

Wildlings 2km from plantation<br />

100% border invaded (61% @ Level 5)


Mullions Range SRA<br />

91% border invaded<br />

>10m pines @ 26 per ha; 61% with cones ( x = 17.5 )


Penrose Hanging<br />

Swamps<br />

Nationally threatened<br />

ecological community<br />

93% border invaded<br />

- 20% at level 5<br />

Pines > 10m<br />

- 159 / ha<br />

- 26% with cones<br />

( x = 2.0 )


Spatial analysis<br />

GIS mapping <strong>of</strong> invaded areas<br />

Analysis <strong>of</strong> site variables:<br />

- Between plantations:<br />

- Plantation age and area (PP), percentage wet vegetation,<br />

annual rainfall<br />

- Within plantations:<br />

- Vegetation type, wind direction, age <strong>of</strong> adjacent compartment<br />

Collate site characteristics common among<br />

invaded areas


Penrose State Forest<br />

1969<br />

0 250 500 1,000<br />

Meters


Between plantations<br />

Dependent variable: Mean infestation index for a plantation<br />

Predictor variable Beta Wald 2 p-value<br />

Plantation size


Mean Infestation Index<br />

5<br />

4<br />

3<br />

2<br />

1<br />

R = 0.371<br />

P = 0.057<br />

0<br />

20<br />

40<br />

60<br />

Residence time (years)<br />

80


Mean Infestation Index<br />

5<br />

4<br />

3<br />

2<br />

1<br />

R = 0.371<br />

P = 0.057<br />

0<br />

20<br />

40<br />

60<br />

Residence time (years)<br />

80


5<br />

> 40 yrs residence time<br />

≤ 40 yrs residence time<br />

Mean Infestation Index<br />

4<br />

3<br />

2<br />

1<br />

0<br />

0<br />

20<br />

Plantation Size x 1000 ha<br />

40


Mean Infestation Index<br />

5<br />

4<br />

3<br />

2<br />

1<br />

R = - 0.301<br />

P = 0.127<br />

> 40 yrs residence time<br />

≤ 40 yrs residence time<br />

Buccleugh<br />

0<br />

0<br />

20<br />

Plantation Size x 1000 ha<br />

40


Mean infestation Index<br />

5<br />

4<br />

3<br />

2<br />

1<br />

> 40 yrs residence time<br />

≤ 40 yrs residence time<br />

Buccleugh<br />

0<br />

0<br />

20<br />

40<br />

60<br />

80<br />

Percentage wet vegetation<br />

100


Impacts<br />

Plantations as the<br />

extreme case: ‘biological<br />

deserts’<br />

Reduced structural and<br />

species diversity<br />

Reduced light levels<br />

Continuous pine needle<br />

cover


Open Eucalypt<br />

Canopy Cover<br />

Invaded<br />

Plantation<br />

20-30% 50-70% 55-80%<br />

Field germination trials<br />

2 species (Acacia terminalis and Eucalyptus sieberi)<br />

880 seeds in each treatment (Open, Invaded, Plantation)<br />

Replicated at 2 sites


Mean emergence % +SE<br />

50<br />

40<br />

30<br />

20<br />

10<br />

a<br />

A<br />

b<br />

AB<br />

b<br />

B<br />

Acacia terminalis<br />

Eucalyptus sieberi<br />

0<br />

open invaded plantation


Mean emergence % +SE<br />

50<br />

40<br />

30<br />

20<br />

10<br />

a<br />

A<br />

b<br />

AB<br />

b<br />

B<br />

A<br />

Acacia terminalis<br />

Eucalyptus sieberi<br />

B<br />

B<br />

0<br />

open invaded plantation open invaded plantation<br />

Autumn/winter<br />

Spring/summer


Litter Impacts<br />

<br />

<br />

<strong>Pinus</strong> <strong>radiata</strong> litter is<br />

known to inhibit<br />

germination (ethylene<br />

production)<br />

(Lill & McWha, 1976)<br />

Physical barrier to<br />

seedlings<br />

<br />

Is there a threshold<br />

density <strong>of</strong> litter that<br />

inhibits germination?


Litter Traps<br />

<br />

Determine rates <strong>of</strong><br />

litter fall from self<br />

sown pines<br />

<br />

Litter traps in invaded<br />

areas<br />

Litter trap in invaded Eucalypt woodland


1000<br />

<strong>Pinus</strong> <strong>radiata</strong><br />

Eucalyptus spp.<br />

E<br />

750<br />

A<br />

Pine litterfall Max:<br />

1478 kg/ha/yr<br />

Mean litterfall kg/ha +SE<br />

a<br />

B<br />

500<br />

250<br />

b<br />

b<br />

C<br />

c<br />

D<br />

c<br />

b<br />

D<br />

bc<br />

C<br />

0<br />

Feb June Sep Dec Mar Jun Sep<br />

2005 2006


Litter Impacts<br />

Field and glasshouse studies<br />

Compare Pine and Eucalypt litter <strong>impacts</strong> on<br />

native germination (Acacia terminalis and<br />

Eucalyptus sieberi)


Eucalyptus sieberi<br />

A<br />

A<br />

A<br />

A<br />

a<br />

a<br />

B<br />

b b b<br />

SIG at p


Pines as sleeper weeds?<br />

• Sleepers - Lag period prior to rapid spread<br />

• Pines slow growing - low priority<br />

• Potential for large <strong>impacts</strong><br />

• Focus on control in early stages<br />

Mimosa pigra<br />

Tamarix aphylla


Quantifying <strong>impacts</strong><br />

• Impacts are context dependent<br />

– PP x E interaction<br />

– temporal variation in response<br />

• Knowledge <strong>of</strong> <strong>impacts</strong> is critical to<br />

assessing risk


Acknowledgements<br />

ForestsNSW and DECC for permission to<br />

carry out the work<br />

Funding<br />

Australian Federation <strong>of</strong> University Women - SA<br />

Australian Geographic<br />

<strong>Ecological</strong> Society <strong>of</strong> Australia<br />

Linnean Society <strong>of</strong> NSW


<strong>Ecological</strong> <strong>impacts</strong> <strong>of</strong><br />

<strong>invasive</strong> <strong>Pinus</strong> <strong>radiata</strong><br />

Moira Williams and Glenda Wardle: School <strong>of</strong> Biological Sciences,<br />

University <strong>of</strong> Sydney


Invasion success<br />

Characteristics <strong>of</strong> the species<br />

- Superior traits<br />

- Greater plasticity<br />

Characteristics <strong>of</strong> environment<br />

Blackberry<br />

- Species rich areas resist invasion<br />

Propagule pressure<br />

Bridal creeper


Predicting Invasion Impacts<br />

Quantification <strong>of</strong> <strong>impacts</strong> to prioritise species<br />

Focus control and research efforts<br />

(Parker et al., 1999)<br />

Mimosa Salvinia Prickly Acacia


“Holy Grail <strong>of</strong> invasion biology”<br />

(Simberl<strong>of</strong>f, 2006)


Tree invasions<br />

Melaleuca quinquinervia<br />

in Florida<br />

Willow (Salix Spp.) in<br />

Australasia<br />

Acacia and Eucalyptus<br />

species in South Africa<br />

and Europe<br />

Pines in the southern<br />

hemisphere<br />

(Richardson et al 1994)


Why study pines?<br />

Known age and extent <strong>of</strong> source populations<br />

Extensive source <strong>of</strong> seeds in plantations<br />

<br />

<br />

Plantations expose a range <strong>of</strong> vegetation<br />

communities<br />

Conspicuous in native eucalypt vegetation


<strong>Pinus</strong> <strong>radiata</strong><br />

Restricted native<br />

range in California<br />

(~5000ha)<br />

Major timber crop<br />

Grown in large<br />

commercial<br />

plantations across<br />

Southern<br />

Hemisphere


P. <strong>radiata</strong> the invader<br />

South Africa (Richardson and Brown, 1986)<br />

New Zealand (Ledgard & Belton 1985)<br />

Australia (Williams & Wardle, 2005; Burdon & Chilvers 1977)<br />

Chile (Bustamante & Simonetti, 2005)<br />

Fynbos in South Africa<br />

Grasslands in New Zealand


<strong>Pinus</strong> <strong>radiata</strong> in Australia<br />

Major s<strong>of</strong>twood species<br />

~ 700,000 ha<br />

Majority grown in NSW and VIC<br />

Naturalised in all states it is grown<br />

Significant environmental weed<br />

(Randall & Kessal, 2004)


Invasion process<br />

• Densities <strong>of</strong> up to 1000/ha in<br />

areas close to plantation<br />

(Williams & Wardle 2005)<br />

• Long distance dispersal <strong>of</strong><br />

wildlings up to 4km from<br />

plantation<br />

• Second generation wildlings<br />

- creation <strong>of</strong> dense stands<br />

• Drier vegetation types more<br />

susceptible to invasion


Bird dispersal<br />

Yellow Tailed Black Cockatoo<br />

(Calyptorhynchus funereus)<br />

<br />

Feed on cones and carry seeds long distances


Our Research<br />

Determine the current extent <strong>of</strong> <strong>Pinus</strong><br />

<strong>radiata</strong> invasion in Australia<br />

Investigate factors facilitating pine spread<br />

Determine the ecological <strong>impacts</strong> <strong>of</strong><br />

invasion


Survey Methods<br />

Drive border <strong>of</strong> plantation<br />

Score level <strong>of</strong> pine infestation (0 to 5) every<br />

100m<br />

INFESTATION INDEX


29 plantations surveyed<br />

Extent <strong>of</strong> spread<br />

<br />

<br />

17 with no or little spread<br />

(Mean index


Lidsdale State Forest<br />

Wildlings 2km from plantation<br />

100% border invaded (61% @ Level 5)


Mullions Range SRA<br />

91% border invaded<br />

>10m pines @ 26 per ha; 61% with cones ( x = 17.5 )


Penrose Hanging<br />

Swamps<br />

Nationally threatened<br />

ecological community<br />

93% border invaded<br />

- 20% at level 5<br />

Pines > 10m<br />

- 159 / ha<br />

- 26% with cones<br />

( x = 2.0 )


Spatial analysis<br />

GIS mapping <strong>of</strong> invaded areas<br />

Analysis <strong>of</strong> site variables:<br />

- Between plantations:<br />

- Plantation age and area (PP), percentage wet vegetation,<br />

annual rainfall<br />

- Within plantations:<br />

- Vegetation type, wind direction, age <strong>of</strong> adjacent compartment<br />

Collate site characteristics common among<br />

invaded areas


Penrose State Forest<br />

1969<br />

0 250 500 1,000<br />

Meters


Between plantations<br />

Dependent variable: Mean infestation index for a plantation<br />

Predictor variable Beta Wald 2 p-value<br />

Plantation size


Mean Infestation Index<br />

5<br />

4<br />

3<br />

2<br />

1<br />

R = 0.371<br />

P = 0.057<br />

0<br />

20<br />

40<br />

60<br />

Residence time (years)<br />

80


Mean Infestation Index<br />

5<br />

4<br />

3<br />

2<br />

1<br />

R = 0.371<br />

P = 0.057<br />

0<br />

20<br />

40<br />

60<br />

Residence time (years)<br />

80


5<br />

> 40 yrs residence time<br />

≤ 40 yrs residence time<br />

Mean Infestation Index<br />

4<br />

3<br />

2<br />

1<br />

0<br />

0<br />

20<br />

Plantation Size x 1000 ha<br />

40


Mean Infestation Index<br />

5<br />

4<br />

3<br />

2<br />

1<br />

R = - 0.301<br />

P = 0.127<br />

> 40 yrs residence time<br />

≤ 40 yrs residence time<br />

Buccleugh<br />

0<br />

0<br />

20<br />

Plantation Size x 1000 ha<br />

40


Mean infestation Index<br />

5<br />

4<br />

3<br />

2<br />

1<br />

> 40 yrs residence time<br />

≤ 40 yrs residence time<br />

Buccleugh<br />

0<br />

0<br />

20<br />

40<br />

60<br />

80<br />

Percentage wet vegetation<br />

100


Impacts<br />

Plantations as the<br />

extreme case: ‘biological<br />

deserts’<br />

Reduced structural and<br />

species diversity<br />

Reduced light levels<br />

Continuous pine needle<br />

cover


Open Eucalypt<br />

Canopy Cover<br />

Invaded<br />

Plantation<br />

20-30% 50-70% 55-80%<br />

Field germination trials<br />

2 species (Acacia terminalis and Eucalyptus sieberi)<br />

880 seeds in each treatment (Open, Invaded, Plantation)<br />

Replicated at 2 sites


Mean emergence % +SE<br />

50<br />

40<br />

30<br />

20<br />

10<br />

a<br />

A<br />

b<br />

AB<br />

b<br />

B<br />

Acacia terminalis<br />

Eucalyptus sieberi<br />

0<br />

open invaded plantation


Mean emergence % +SE<br />

50<br />

40<br />

30<br />

20<br />

10<br />

a<br />

A<br />

b<br />

AB<br />

b<br />

B<br />

A<br />

Acacia terminalis<br />

Eucalyptus sieberi<br />

B<br />

B<br />

0<br />

open invaded plantation open invaded plantation<br />

Autumn/winter<br />

Spring/summer


Litter Impacts<br />

<br />

<br />

<strong>Pinus</strong> <strong>radiata</strong> litter is<br />

known to inhibit<br />

germination (ethylene<br />

production)<br />

(Lill & McWha, 1976)<br />

Physical barrier to<br />

seedlings<br />

<br />

Is there a threshold<br />

density <strong>of</strong> litter that<br />

inhibits germination?


Litter Traps<br />

<br />

Determine rates <strong>of</strong><br />

litter fall from self<br />

sown pines<br />

<br />

Litter traps in invaded<br />

areas<br />

Litter trap in invaded Eucalypt woodland


1000<br />

<strong>Pinus</strong> <strong>radiata</strong><br />

Eucalyptus spp.<br />

E<br />

750<br />

A<br />

Pine litterfall Max:<br />

1478 kg/ha/yr<br />

Mean litterfall kg/ha +SE<br />

a<br />

B<br />

500<br />

250<br />

b<br />

b<br />

C<br />

c<br />

D<br />

c<br />

b<br />

D<br />

bc<br />

C<br />

0<br />

Feb June Sep Dec Mar Jun Sep<br />

2005 2006


Litter Impacts<br />

Field and glasshouse studies<br />

Compare Pine and Eucalypt litter <strong>impacts</strong> on<br />

native germination (Acacia terminalis and<br />

Eucalyptus sieberi)


Eucalyptus sieberi<br />

A<br />

A<br />

A<br />

A<br />

a<br />

a<br />

B<br />

b b b<br />

SIG at p


Pines as sleeper weeds?<br />

• Sleepers - Lag period prior to rapid spread<br />

• Pines slow growing - low priority<br />

• Potential for large <strong>impacts</strong><br />

• Focus on control in early stages<br />

Mimosa pigra<br />

Tamarix aphylla


Quantifying <strong>impacts</strong><br />

• Impacts are context dependent<br />

– PP x E interaction<br />

– temporal variation in response<br />

• Knowledge <strong>of</strong> <strong>impacts</strong> is critical to<br />

assessing risk


Acknowledgements<br />

ForestsNSW and DECC for permission to<br />

carry out the work<br />

Funding<br />

Australian Federation <strong>of</strong> University Women - SA<br />

Australian Geographic<br />

<strong>Ecological</strong> Society <strong>of</strong> Australia<br />

Linnean Society <strong>of</strong> NSW

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