Ecological impacts of invasive Pinus radiata
Ecological impacts of invasive Pinus radiata
Ecological impacts of invasive Pinus radiata
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
<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