Collaborative Research: Rhizosphere priming and C-N dynamics in grassland ecosystems in transition

根际引发是本研究的重点，是活根影响土壤储存和释放碳和氮的潜力的过程。在全球范围内，土壤储存的碳是大气中碳的两倍，并调节氮素供应，以维持植物生产力，同时防止过量的氮素损失。实验室研究表明，根际引发可能是控制土壤二氧化碳排放和有机质氮素释放的关键。然而，在实际生态系统中，根际启动对土壤碳、氮转化的控制一直很难研究，而且还没有被很好地理解。这一点很重要，因为许多环境变化可能会改变根际启动，对碳储存和氮循环产生潜在的重大后果。通过测量植物和土壤中的碳和氮同位素示踪剂，这项研究将跟踪不同碳源和氮源的命运，并区分它们对美国中部草原土壤功能的贡献。这项研究还使用了具有不同根系特征的植物，以确定植物对根际引发的不同影响。在三年的时间里，这项研究将解决两个主要问题：(1)在现实土壤条件下，根际引发有机质分解的幅度是多少？以及(2)不同的植物和土壤特性如何影响季节、植物类型和不同土壤的启动？这个项目是一个全面努力的开始，旨在破译和证明根在实际草原生态系统中的重要作用。这个项目的结果将帮助我们了解植物和环境条件的变化如何影响空气质量和土壤中氮素的损失。它将培养9名本科生、3名研究生和1名博士后科学家。招募参与者将侧重于代表性不足的群体，并建立在加利福尼亚州、堪萨斯州和俄克拉何马州现有计划的基础上，以增加项目参与者的多样性。结果将被纳入三个州的本科生和研究生课程，项目数据将在网站上提供。这项计划还将有助于加强公众教育和提高公众意识，并让公众认识到根基在提供草原基本服务方面的重要性。最后，堪萨斯州Konza Prairie长期生态研究基地的实验地点和可见度为公共教育提供了独特的机会，包括为校园计划和其他外联活动开发模块。

Rhizosphere priming, the focus of this study, is the process by which living roots affect the potential for soils to store and release carbon and nitrogen. On a global basis, soils store twice as much carbon as is in the atmosphere and regulate the nitrogen supply to maintain plant productivity while preventing excess nitrogen losses. Laboratory studies indicate that rhizosphere priming is likely a key control on soil CO2 emissions and the release of nitrogen from organic matter. However, the control of rhizosphere priming on soil carbon and nitrogen transformations in real ecosystems has been difficult to study and is not well understood. This is important because many environmental changes could alter rhizosphere priming, with potentially large consequences for carbon storage and nitrogen cycling. By measuring carbon and nitrogen isotope tracers in plants and soils, this study will follow the fate of different carbon and nitrogen sources and separate their contributions the functioning of the soil in grasslands of the central United States. This study also uses plants with different kinds of root characteristics to figure out the different influences plants can have on rhizosphere priming. Over three years, this study will address two main questions: (1) What is the magnitude of rhizosphere priming on the breakdown of organic matter under realistic soil conditions? and (2) How do different plant and soil characteristics affect priming across seasons, types of plants and different soils? This project is that start of a comprehensive effort to decipher and ground truth the important roles of of roots in actual grassland ecosystems.The results of this project will help us understand how changes in plants and environmental conditions affect air quality and the loss of nitrogen from soils. It will train nine undergraduate students, three graduate students, and a post-doctoral scientist. Recruitment of participants will focus on underrepresented groups and build on existing programs in California, Kansas and Oklahoma to increase the diversity of the project participants. Results will be incorporated into undergraduate and graduate courses in the three states and project data will be made available on a web site. This project will also help to enhance public education and awareness and to inform the general public of the importance of roots in providing essential services from our grasslands. Finally, the location and visibility of the experiment at the Konza Prairie Long-Term Ecological Research site in Kansas offers unique opportunities for public education, including development of modules for the schoolyard programs and other outreach activities.