DISSERTATION RESEARCH: Connecting dryland soil trace gas emissions of NOx, N2O and CO2 to microbial community dynamics along a nitrogen deposition gradient

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The importance of species diversity and community composition for ecosystem processes has been shown in plants and animals, but fewer studies have focused on soil microorganisms. Soil microorganisms may play an important role in processes contributing to climate change and air pollution through production of greenhouse gases such as carbon dioxide and nitrogen oxides. Scientists currently estimate the existence of millions to billions of microbial species, but how changes in species composition relate to ecosystem function is not well understood. This study will combine measurements of soil gas production with advanced techniques for DNA analysis to examine diversity of soil bacteria and fungi to address the following questions: 1) How does air pollution affect species composition of soil microorganisms and what is the impact on ecosystem processes? 2) To what extent does microbial community composition influence feedbacks to climate change and air pollution? This study will use experimental manipulations in the Colorado Desert of southern California to investigate how temperature, soil moisture and nutrient availability regulate soil microbiological feedbacks. The results will increase predictive power for the impact of future climate scenarios on ecosystem processes, and contribute to a deeper understanding of microbial ecology. Drylands cover greater than 30% of the global land surface. Increasing human activity in drylands intensifies air pollution with unknown consequences. Knowledge of the relationships between microbial community structure and soil feedbacks to global change drivers can inform land management strategies and be incorporated into agricultural practices to reduce pollution and improve efficiency. Furthermore, this research will inform regulatory bodies so that soil feedbacks are considered when emission standards are set. Finally, the project will provide new educational opportunities to a wide audience, including graduate, undergraduate, and primary students from local schools. These opportunities will feature new environmental genetic techniques that have only recently become available. The skills and knowledge gained from the study will be incorporated into community outreach events that aim to excite children from local elementary and high schools about science and college opportunities.