Human-induced changes in the environment have the ability to alter soil nutrient cycles, thereby affecting the many ecosystem services on which humans rely. However, despite the fact that these changes often occur simultaneously, few studies have investigated their interactive effects on the important belowground components of an ecosystem. Because nitrogen (N) is the limiting nutrient for plant growth in most terrestrial systems, it is essential to understand how N cycling responds to both biotic and abiotic changes. This project will contribute to global change ecology by assessing how soil microorganisms that mediate N cycling respond to the interaction of three primary changes in the environment: elevated N deposition, cattle grazing, and invasive plants. Soil has been sampled from beneath plant communities that were subjected to simulated N deposition, cattle grazing and experienced the invasion of an exotic plant species. Microbial DNA will be extracted from the soil to understand how N-cycling microorganisms respond to the treatments. Changes in the microbial community will then be related to changes in N cycling processes. Results from this project will contribute new insight into community level changes in microorganisms that are responsible for key steps in the N cycle, ultimately helping to advance current knowledge of nutrient dynamics in terrestrial ecosystems.
Project results will be presented at national and international conferences, such as the International Society of Microbial Ecology, in order to ensure widespread dissemination across the scientific community. Workforce development will occur through the training of two undergraduates by their full participation in the research project. Additionally, the results will be published in peer-reviewed journals and findings will be presented to the local community via seminars. Because the University of California, Merced, is located in the Central Valley, a large proportion of the students who receive outreach will be from underrepresented groups.
