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,

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

Species Fallopia japonica Pteridium aquilinum

Field Microclimate Simulations Passive 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 Data Average 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 japonicaPteridium aquilinum All significant at p<0.001

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

Biomass Production Pteridium aquilinum Invasion: p<0.03 Microclimate (Invaded) p<0.03 Microclimate (Uninvaded) p<0.002

Decomposition Litter Bags 2008 F. japonica P. aquilinum Invasion: p<0.01 Microclimate (Invaded): p<0.01

Mycorrhizal Inoculum Potential Bioassay with White Clover F. japonica P. aquilinum Invasion: p< Microclimate (2007): p<0.001 Year p< Microclimate (2008): p< Year p<0.002

Microarthropods 2007

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.