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

在整个21世纪，温度、降水、大气二氧化碳浓度和氮沉降的变化可能会继续发生，并将对地球上的森林、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，而这种相互作用尚不清楚。鉴于这一科学空白，本研究的目标是增加对变暖、降水、二氧化碳和氮对长期生态系统响应的相互作用的理解。为了实现这一目标，将在明尼苏达州的一个独特的露天草地实验中进行实验操作，以创建环境温度和升高的温度（环境温度和+2°C），当前和减少的生长季节降水（环境降雨量和55%的环境降雨量），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），以及环境和丰富的氮供应（通过两个水平的土壤氮供应来实现）的所有组合。该研究将确定这四个全球变化因素对植物和土壤生物性能的相互作用，从而对植物生产、土壤肥力和碳获取和储存产生影响。这个项目的结果还将有助于开发模型，预测植被的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，从而影响全球气候系统。该项目将培养包括来自代表性不足群体的学生在内的多元化本科生群体，并与来自美国和世界各地的科学家建立联系。结果将纳入针对K-12教育工作者和旨在培训教师学习全球变化和可持续性课程的外联活动。研究人员将通过授课、接受媒体采访、参加公共论坛、向政府官员提供建议等方式对学生和公众进行教育。

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.