Projected warmer temperatures and increased rainfall in the northeastern United States are expected to disrupt the growth physiology of both native and invasive species. While there are many studies on the effects of climate change on plant phenology, growth, and reproduction, very few studies examine how projected abiotic conditions may affect dispersal traits. We used open top chambers (OTC) and water addition treatments to change the microsite characteristics of the invasive thistle, Carduus nutans. Treatments were designed to mimic local projections for future climate change in the Northeastern USA. Primary capitula were harvested and assessed for differences in morphological characteristics such as capitulum size and stem diameter. Subsequently, we subjected the capitula to trials in a wind tunnel to assess differences in seed release.

Results/Conclusions

We found a significant interaction between additional water and warming (P<0.05). Specifically, water addition and warming significantly increased both the morphological characteristics of primary capitula as well as seed release in the wind tunnel (P<0.05). These results suggest that climate change will alter the morphology and dispersal characteristics of the invasive thistle Carduus nutans. These alterations may have implications for the spread of invasive plants in the context of a changing climate.