Todd Dawson, Professor

Closed (1) Determining source and cycling of nitrogen in a deep forest rhizosphere using stable isotope and biogeochemical approaches

Applications for fall 2021 are now closed for this project.

This project seeks to describe the source and cycling of nitrogen (N), an essential nutrient to plant growth and function, in a deep, weathered bedrock rhizosphere within a CA mixed hardwood-evergreen forest at the UC Angelo Coast Range Reserve. Forests along the CA coast root deeply into weathered bedrock and rely on deep water resources well beyond soil horizons year-round. Little is known, however, about how these deep rhizospheres (composed of plant roots and their associated microbiome) drive nutrient cycling and dynamics at depth. In this project, we combine stable isotope and biogeochemical techniques to ask: (1) how do the chemical forms and concentrations of biologically available N change year round; (2) what is the source and fate of this N; and (3) to what extent do dominant tree species utilize this deep N resource?

The URAP student on this project will get experience in the fields of soil chemistry, forest ecology and stable isotope ecology. There will be frequent opportunities for the student to assist with field work in addition to regular lab work. In the lab, the student would help with procedures including: preparing leaf and soil samples for stable isotope analysis; preparing water samples collected from the field for chemical analysis; extracting soils for available N (NO3- and NH4+); and conducting pH measurements on field soil samples. In the field, the student would learn how to: use specialized field equipment for sampling water from soil and deep (up to 16 m) weathered bedrock; the student would learn how to identify dominant tree species and sample leaves for stable isotope analysis; the student would learn how to take soil cores and identify fine roots of dominant tree species.

The student will meet regularly with their day-to-day supervisor, where the theories and methods they will employ will be explained. The student will be supplied with scholarly articles for them to pursue as they are interested and the student is encouraged to bring their own questions and ideas to drive their learning experience. In addition to their field and lab experiences, the URAP student on this project would be encouraged to attend our weekly lab meetings where graduate students and postdocs present and discuss their current research. This is an excellent opportunity for the student to get more exposure to diverse research in the field of plant ecophysiology. Additionally, students interested in pursuing their own independent research may seek future opportunities in the lab, or future positions for field research in the summer.

Day-to-day supervisor for this project: Kelsey L Crutchfield-Peters, Ph.D. candidate

Qualifications: No qualifications required, but coursework in biology and chemistry desired (we encourage all to apply). The position will be given to a student who demonstrates they are eager to learn forest ecology and plant-soil interactions.

Weekly Hours: 6-8 hrs

Off-Campus Research Site: There will also be opportunities to participate in field work at the UC Angelo Reserve throughout the semester.

Related website:
Related website: A recent paper summarizing this type of work: