Collaborative Research on Feedbacks between Microbial Community Composition, Soil Structure, Plant Growth and Nitrogen Cycling in Ecosystems Exposed to Elevated CO2 and O3

在过去的一个世纪里，大气二氧化碳(CO2)浓度增加了31%，而大气臭氧(O3)浓度在过去40年里每年增加约1%。二氧化碳和臭氧升高对农业的综合影响是直接的，但往往是不可预测的。因此，我们的目标是研究大豆生产力、微生物群落组成的变化与氮循环之间的关系，以响应二氧化碳和臭氧的增加。重点将放在生物固氮，这是一个主要的氮素输入过程，以及硝化和反硝化过程，导致氮素损失。这些氮循环过程将通过稳定同位素技术确定，并将与微生物群落结构联系起来，这将通过分子技术来测量。尽管土壤氮素有效性对植物生长至关重要，但二氧化碳和臭氧浓度升高对土壤维持植物生产力能力的长期影响在很大程度上是未知的。该项目将通过将土壤微生物的结构和功能与氮素的流动联系起来，弥合这一知识鸿沟。这项研究的结果将提高我们对土壤过程在高二氧化碳和高臭氧条件下维持可持续生态系统功能所起的作用的全面理解。随着人口的增加和大气污染对生态系统造成的压力越来越大，这一领域的调查和教育非常重要。

Atmsopheric carbon dioxide (CO2) concentration has increased by 31% during the past century, and atmospheric ozone (O3) concentration has risen about 1 percent per year over the past four decades. The combined influence of elevated CO2 and O3 on agriculture is direct but often unpredictable. Consequently, the goal is to investigate the relationships between changes in soybean productivity, microbial community composition and nitrogen cycling in response to elevated CO2 and O3. The focus will be on biological nitrogen fixation, a major nitrogen input process, and nitrification and denitrification, processes inducing nitrogen losses. These nitrogen cycling processes will be determined with stable isotope techniques and will be linked to the microbial community structure, which will be measured by molecular techniques. Although soil nitrogen availability is crucial for plant growth, the long-term effects of elevated CO2 and O3 on the capacity of the soil to sustain plant productivity is largely unknown. This project will bridge this knowledge gap by linking the structure and function of soil microbes to the flow of nitrogen. The results from this research will improve our overall understanding of the role soil processes play in maintaining sustainable ecosystem functioning under elevated CO2 and O3. This area of inquiry and education is important as increased human population and atmospheric pollution increasingly stress ecosystems.