Changes in temperature, precipitation, atmospheric CO2 concentration, and nitrogen deposition will likely continue to occur throughout the 21st century and will have significant impacts on forests, grasslands, and other vegetation across the planet. However, the effects of each of these factors alone may depend on changes in the other factors, and such interactions are poorly understood. Given this scientific gap, the objective of the proposed study is to increase understanding of the interactive effects of warming, precipitation, CO2, and nitrogen on long-term ecosystem responses. To meet this objective, experimental manipulations will be imposed in a unique open-air grassland experiment in Minnesota, to create all combinations of ambient and elevated temperature (ambient and +2Â°C), current and reduced growing season precipitation (ambient rainfall and 55% of ambient rainfall), ambient and elevated CO2 (current levels and those likely to occur late in the century), and ambient and enriched nitrogen supply (achieved with two levels of soil nitrogen supply). The study will determine the interactive effects of these four global change factors on performance of plants and soil organisms, and hence on plant production, soil fertility, and carbon acquisition and storage. Results of this project will also help in the development of models that predict how changes in vegetation will influence the global climate system through modifying the rise in atmospheric carbon dioxide levels and thus the rate of climate warming.
This project will educate a diverse group of undergraduates, including students from under-represented groups, and build ties to scientists from around the U.S. and the world. Results will be incorporated into outreach activities aimed at K-12 educators and aimed at training teachers in global change and sustainability curricula. Researchers will educate students and the public through classes, interviews with the press, participation in public forums, and advising government officials.