Mauricio C. Mantoani1,3, Conor Sweeney2,3 and Bruce A. Osborne1,3
1UCD School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
2 UCD School of Mathematics and Statistics, University College Dublin, Belfield, Dublin 4, Ireland
3 UCD Earth Institute, University College Dublin, Dublin 4, Belfield, Ireland
Whilst it is often assumed that invasive plant species may benefit more from climate change than native species, there is little information on how they might respond to extreme weather events (EWE), the occurrence and magnitude of which are projected to increase with global warming. Here, we show that the benefits of an increase of two weeks in the length of the growing season were offset by an EWE (i.e. Storm Emma), characterized by low temperature extremes and snowfall. This resulted in a disproportionally greater impact on mature populations of the invasive species Gunnera tinctoria compared to native species. The EWE reduced the total leaf area of the invader by 11-fold, significantly delayed canopy development and reduced shoot biomass by > 85%, leading to a four-fold increase in the number of regenerating species in invaded areas. This also resulted in the loss of most of the inflorescences (83%) from mature plants, although it had a much smaller effect on seedlings of G. tinctoria, which produced new leaves that rapidly expanded after the EWE had passed. Based on this information an EWE may counteract any early growth benefits associated with established plants, but the longer term impacts will depend on the extent to which this compromises seedling growth and development as well as the ability of mature plants to recover vegetative and reproductive growth.