Collaborative Research: The Complexity of Global Change - Interactive Effects of Warming, Water Availability, CO2 and N on Grassland Ecosystem Function

温度、降水、大气二氧化碳浓度和氮沉降的变化可能会在整个21世纪继续发生，并将对全球森林、草原和其他植被产生重大影响。然而，这些因素中的每一个单独的影响可能取决于其他因素的变化，而这种相互作用很少被理解。鉴于这一科学鸿沟，拟议研究的目标是增加对气候变暖、降水、二氧化碳和氮对长期生态系统响应的交互影响的理解。为了实现这一目标，将在明尼苏达州一个独特的露天草原实验中实施实验操作，以创造环境温度和高温(环境温度和+2℃)、当前和生长季降雨量减少(环境降雨量和环境降雨量的55%)、环境和升高的二氧化碳(当前水平和本世纪末可能发生的水平)以及环境和富氮供应(通过两个水平的土壤氮素供应实现)的所有组合。这项研究将确定这四个全球变化因素对植物和土壤有机体表现的交互影响，从而对植物生产、土壤肥力以及碳获取和储存的影响。该项目的结果还将有助于开发模型，预测植被变化将如何通过改变大气二氧化碳水平的上升从而影响气候变暖的速度来影响全球气候系统。该项目将教育不同的本科生群体，包括来自代表性不足群体的学生，并与来自美国和世界各地的科学家建立联系。这些成果将被纳入针对K-12教育工作者的外联活动，旨在培训有关全球变化和可持续发展课程的教师。研究人员将通过课堂、媒体采访、参与公共论坛和为政府官员提供建议来教育学生和公众。

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 +2°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.