Climate Change and Plant Invasions

Bruce Osborne & M. Angeles Rodriguez-Tunon

UCD School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4

Climate Change: A Complexity of Responses and Consequences

From Hellman et al., 2008; Conservation Biology 23, 534-543

Plant Invasions

• Largely speculative; no real comprehensive assessment

• Based on pre-conceived ‘expectations’-species coming from warmer areas MUST establish/increase/have greater impact!

• Predictions hardly ever community/ecosystem based

• Limited by absence of EXPERIMENTAL DATA on establishment/impacts/spread

SpeciesFallopia japonica Pteridium aquilinum

Field Microclimate SimulationsPassive Enclosures

Uninvaded (UI) And Associated Invaded (I) Areas (n=3); Installed for Duration of Growing season; continuous monitoring of microclimate inside/outside

Microclimate Simulations

Microclimatic DataAverage Maximum Values 2008

Change (+/-)

Air Temperature +3.4 °C

Soil Temperature -0.4°C (UI)

+1°C (I)

Soil Moisture Content -33%

Relative Humidity +27%

Change (+/-)

Air Temperature +3.5°C

Soil Temperature +0.34°C (UI)

+0.57°C (I)

Soil Moisture Content -41% (UI)

-21% (I)

Relative Humidity -17%

Fallopia japonica Pteridium aquilinum

All significant at p<0.001

Biomass Production

0

500

1000

1500

2000

InvadedInside

InvadedOutside

UninvadedInside

UninvadedOutside

Biom

ass

(g d

ry w

eigh

t . m

-2)

Litter

Grassland

Fallopia japonica

Fallopia japonica

Invasion: p<0.001Litter production/microclimate (invaded areas) close to significance

Biomass Production

Biomass 2007

0100200300400500600700800

InvadedInside

InvadedOutside

UninvadedInside

UninvadedOutside

Bio

mas

s (g

dry

wei

gh

t .

m-2

)Grassland

Pteridium aquilinum

Pteridium aquilinum

Biomass 2008

0100200300400500600700800

InvadedInside

InvadedOutside

UninvadedInside

UninvadedOutside

Bio

mas

s (g

dry

wei

gh

t .

m-2

)

Grassland

Pteridium aquilinum

Invasion: p<0.03Microclimate (Invaded) p<0.03Microclimate (Uninvaded) p<0.002

DecompositionLitter Bags 2008

0

10

20

30

40

50

60

Invaded Inside Invaded Outside UninvadedInside

UninvadedOutside

DO

M (

%)

0

10

20

30

40

50

60

Invaded Inside Invaded Outside UninvadedInside

UninvadedOutside

DO

M(%

)

F. japonica

P. aquilinum

Invasion: p<0.01Microclimate (Invaded): p<0.01

Mycorrhizal Inoculum PotentialBioassay with White Clover

0

10

20

30

40

50

60

70

80

2007 2008

Ro

ot

colo

niz

atio

n (

%)

Invaded Inside

Invaded Outside

Uninvaded Inside

Uninvaded Outside

0

10

20

30

40

50

60

70

80

2007 2008

Ro

ot

colo

niz

atio

n (

%)

Invaded Inside

Invaded Outside

Uninvaded Inside

Uninvaded Outside

F. japonica

P. aquilinum

Invasion: p<0.0001Microclimate (2007): p<0.001Year p<0.0001

Microclimate (2008): p< 0.0001Year p<0.002

Microarthropods2007

Fallopia japonica Pteridium aquilinum Collembola

(sp/10g soil) Oribatida (fam/10g soil)

Collembola (sp/10g soil)

Oribatida (fam/10g soil)

Totals 14 13 28 19 Invaded Inside 0.19 0.13 0.21 0.12 11.93 14.49 25.84 5.18 Invaded Outside 0.17 0.11 0.17 0.11 13.31 34.26 30.15 8.17 Uninvaded Inside 0.24 0.02 0.21 0.19 8.52 5.53 22.50 9.3 Uninvaded Outside 0.29 0.03 0.24 0.01 26.57 34.39 39.55 29.1

Summary• Impacts of microclimate simulations

species/site/ecosystem/year-dependent

• Simulations can decrease/cause no change in productivity, but RELATIVE performance of invader can increase at ECOSYSTEM scale

• Emphasizes the importance of ecosystem-level analyses at a range of locations

• Effects can be rapid-decomposition, mycorrhizal inoculum potential

Acknowledgements

We thank the support of the EPA through the BIOCHANGE project, the UCD Plant Ecophysiology group and Eugene Sherry, Ingrid Arts, Maria Long and Ralph Twomey for support. We also thank the landowners for access to sites, and the NPWS and Co.

Clare Heritage Officers for assistance.