Regional climate models predict a 2.9~5.3°C increase in average annual temperature and a changed precipitation pattern featuring a 12%~30% increase of winter precipitation in the U. S Northeast by the end of the century. To examine how potential future climate change affects the seedling emergence, survivorship, growth and reproduction of two invasive thistles, Carduus nutans and C. acanthoides, we conducted a climate manipulation experiment to examine the possible outcome of increased temperature and precipitation. We achieved a 1.5°C average daily temperature increase by using fiberglass Open Top Chambers (OTCs) and a 30% increase in winter precipitation by using passive precipitation collectors.

Results/Conclusions
The experiment resulted in an array of 80 plots with 40 plots having OTCs. Each replicate contained four rosettes and twenty-five seeds. Our results show that increased temperature did not have a significant effect on fall seedling emergence. We anticipate that increased temperature enhances seedling survivorship and ultimate plant height, which may affect dispersal distance. Warming also will likely result in earlier flowering. Data from spring 2008 will yield additional results. Our work suggests that future management of biological invasions should consider potential responses of invasive species to climate change.